trihexyphenidyl (Rx)

Brand and Other Names:Artane, Trihex
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Dosing & Uses

AdultPediatricGeriatric

Dosage Forms & Strengths

tablets

  • 2mg
  • 5mg

elixir

  • 0.4mg/mL

Parkinson Disease

Initial: 1 mg PO first day, then increase by 2 mg q3-5days until reach 6-10 mg/days

Maintenance: 5-15 mg/day PO divided q6-8hr

Use SR product once stabilized on regular release product; when used with levodopa, generally use 3-6 mg/day in divided doses

Do not crush SR product

Monitor: IOP

Drug-induced Extrapyramidal Symptoms

1 mg/day PO initially; increase as necessary to maintenance range of 5-15 mg/day PO divided q6-8hr

Safety and efficacy not established

Nonanticholinergic antiparkinson agents should be considered first when treating Parkinson Disease (Beers Criteria)

Not recommended for preventing extrapyramidal symptoms

Parkinsonism

5-15 mg/day PO divided q6-8hr

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Interactions

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              Serious - Use Alternative (6)

              • glucagon

                glucagon increases toxicity of trihexyphenidyl by Other (see comment). Avoid or Use Alternate Drug. Comment: Coadministration of anticholinergic drugs and glucagon increase the risk of gastrointestinal adverse reactions due to additive effects on inhibition of gastrointestinal motility. .

              • glucagon intranasal

                glucagon intranasal increases toxicity of trihexyphenidyl by Other (see comment). Avoid or Use Alternate Drug. Comment: Coadministration of anticholinergic drugs and glucagon increase the risk of gastrointestinal adverse reactions due to additive effects on inhibition of gastrointestinal motility. .

              • glycopyrronium tosylate topical

                glycopyrronium tosylate topical, trihexyphenidyl. Either increases effects of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Coadministration of glycopyrronium tosylate topical with other anticholinergic medications may result in additive anticholinergic adverse effects.

              • revefenacin

                revefenacin and trihexyphenidyl both decrease cholinergic effects/transmission. Avoid or Use Alternate Drug. Coadministration may cause additive anticholinergic effects.

              • secretin

                trihexyphenidyl decreases effects of secretin by pharmacodynamic antagonism. Avoid or Use Alternate Drug. Concomitant use of anticholinergic drugs may cause a hyporesponse to stimulation testing with secretin. Discontinue anticholinergic drugs at least 5 half-lives before administering secretin.

              • umeclidinium bromide/vilanterol inhaled

                trihexyphenidyl, umeclidinium bromide/vilanterol inhaled. Either increases toxicity of the other by pharmacodynamic synergism. Avoid or Use Alternate Drug. Concomitant use with other anticholinergic-containing drugs may lead to additive anticholinergic adverse effects.

              Monitor Closely (69)

              • abobotulinumtoxinA

                abobotulinumtoxinA increases effects of trihexyphenidyl by pharmacodynamic synergism. Use Caution/Monitor. Use of anticholinergic drugs after administration of botulinum toxin-containing products may potentiate systemic anticholinergic effects.

              • aclidinium

                aclidinium and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor.

              • amantadine

                trihexyphenidyl, amantadine. Mechanism: pharmacodynamic synergism. Use Caution/Monitor. Potential for increased anticholinergic adverse effects.

              • amitriptyline

                trihexyphenidyl and amitriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • amoxapine

                trihexyphenidyl and amoxapine both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • anticholinergic/sedative combos

                anticholinergic/sedative combos and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • atropine

                atropine and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • atropine IV/IM

                atropine IV/IM and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor.

              • belladonna alkaloids

                belladonna alkaloids and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • belladonna and opium

                belladonna and opium and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • benztropine

                benztropine and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • chlorpromazine

                trihexyphenidyl decreases levels of chlorpromazine by pharmacodynamic antagonism. Use Caution/Monitor.

                chlorpromazine increases effects of trihexyphenidyl by pharmacodynamic synergism. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • clomipramine

                trihexyphenidyl and clomipramine both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • clozapine

                clozapine increases effects of trihexyphenidyl by pharmacodynamic synergism. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • cyclizine

                cyclizine and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • cyclobenzaprine

                cyclobenzaprine and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • darifenacin

                darifenacin and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • desipramine

                trihexyphenidyl and desipramine both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • dicyclomine

                dicyclomine and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • dimenhydrinate

                dimenhydrinate increases toxicity of trihexyphenidyl by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects.

              • diphenhydramine

                diphenhydramine and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • donepezil

                donepezil decreases effects of trihexyphenidyl by pharmacodynamic antagonism. Use Caution/Monitor.

              • doxepin

                trihexyphenidyl and doxepin both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • droperidol

                droperidol increases effects of trihexyphenidyl by pharmacodynamic synergism. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • fesoterodine

                fesoterodine and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • flavoxate

                flavoxate and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • fluphenazine

                trihexyphenidyl decreases levels of fluphenazine by pharmacodynamic antagonism. Use Caution/Monitor.

                fluphenazine increases effects of trihexyphenidyl by pharmacodynamic synergism. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • galantamine

                galantamine decreases effects of trihexyphenidyl by pharmacodynamic antagonism. Use Caution/Monitor.

              • glycopyrrolate

                glycopyrrolate and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • glycopyrrolate inhaled

                glycopyrrolate inhaled and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • haloperidol

                haloperidol increases effects of trihexyphenidyl by pharmacodynamic synergism. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • homatropine

                homatropine and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • hyoscyamine

                hyoscyamine and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • hyoscyamine spray

                hyoscyamine spray and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor.

              • imipramine

                trihexyphenidyl and imipramine both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • ipratropium

                ipratropium and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • loxapine

                trihexyphenidyl decreases levels of loxapine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor.

                trihexyphenidyl decreases levels of loxapine by pharmacodynamic antagonism. Use Caution/Monitor.

                loxapine increases effects of trihexyphenidyl by pharmacodynamic synergism. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • loxapine inhaled

                loxapine inhaled increases effects of trihexyphenidyl by pharmacodynamic synergism. Use Caution/Monitor. Additive anticholinergic effects, possible hypoglycemia.

                trihexyphenidyl decreases levels of loxapine inhaled by pharmacodynamic antagonism. Use Caution/Monitor.

              • maprotiline

                trihexyphenidyl and maprotiline both decrease cholinergic effects/transmission. Use Caution/Monitor.

              • meclizine

                meclizine and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • methscopolamine

                methscopolamine and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • nortriptyline

                trihexyphenidyl and nortriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • olanzapine

                olanzapine increases effects of trihexyphenidyl by pharmacodynamic synergism. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • oliceridine

                trihexyphenidyl increases toxicity of oliceridine by Other (see comment). Use Caution/Monitor. Comment: Anticholinergic drugs may increase risk of urinary retention and/or severe constipation, which may lead to paralytic ileus. Monitor for signs of urinary retention or reduced gastric motility if oliceridine is coadministered with anticholinergics.

              • onabotulinumtoxinA

                onabotulinumtoxinA and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • orphenadrine

                trihexyphenidyl and orphenadrine both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • oxybutynin

                oxybutynin and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • oxybutynin topical

                oxybutynin topical and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • oxybutynin transdermal

                oxybutynin transdermal and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • perphenazine

                trihexyphenidyl decreases levels of perphenazine by pharmacodynamic antagonism. Use Caution/Monitor.

                perphenazine increases effects of trihexyphenidyl by pharmacodynamic synergism. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • physostigmine

                physostigmine increases and trihexyphenidyl decreases cholinergic effects/transmission. Effect of interaction is not clear, use caution. Use Caution/Monitor.

              • pimozide

                pimozide increases effects of trihexyphenidyl by pharmacodynamic synergism. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • pramlintide

                pramlintide, trihexyphenidyl. Either increases effects of the other by pharmacodynamic synergism. Use Caution/Monitor. Synergistic inhibition of GI motility.

              • prochlorperazine

                trihexyphenidyl decreases levels of prochlorperazine by pharmacodynamic antagonism. Use Caution/Monitor.

                prochlorperazine increases effects of trihexyphenidyl by pharmacodynamic synergism. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • promethazine

                trihexyphenidyl decreases levels of promethazine by pharmacodynamic antagonism. Use Caution/Monitor.

                promethazine increases effects of trihexyphenidyl by pharmacodynamic synergism. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • propantheline

                propantheline and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • protriptyline

                trihexyphenidyl and protriptyline both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • quetiapine

                quetiapine increases effects of trihexyphenidyl by pharmacodynamic synergism. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • risperidone

                risperidone increases effects of trihexyphenidyl by pharmacodynamic synergism. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • scopolamine

                scopolamine and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • solifenacin

                solifenacin and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • thioridazine

                trihexyphenidyl decreases levels of thioridazine by pharmacodynamic antagonism. Use Caution/Monitor.

                thioridazine increases effects of trihexyphenidyl by pharmacodynamic synergism. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • thiothixene

                thiothixene increases effects of trihexyphenidyl by pharmacodynamic synergism. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • tiotropium

                tiotropium and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • tolterodine

                tolterodine and trihexyphenidyl both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • tranylcypromine

                tranylcypromine, trihexyphenidyl. Other (see comment). Use Caution/Monitor. Comment: Anti-parkinsonism drugs should be used with caution in patients receiving tranylcypromine since severe reactions have been reported.

              • trifluoperazine

                trihexyphenidyl decreases levels of trifluoperazine by pharmacodynamic antagonism. Use Caution/Monitor.

                trifluoperazine increases effects of trihexyphenidyl by pharmacodynamic synergism. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • trimipramine

                trihexyphenidyl and trimipramine both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              • trospium chloride

                trihexyphenidyl and trospium chloride both decrease cholinergic effects/transmission. Use Caution/Monitor. Potential for additive anticholinergic effects.

              Minor (1)

              • levodopa

                trihexyphenidyl, levodopa. Other (see comment). Minor/Significance Unknown. Comment: Anticholinergic agents may enhance the therapeutic effects of levodopa; however, anticholinergic agents can exacerbate tardive dyskinesia. In high dosage, anticholinergics may decrease the effects of levodopa by delaying its GI absorption. .

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              Adverse Effects

              >10%

              Anticholinergic side effects (30-50%)

              Rash

              <1%

              Suppurative parotitis

              Hallucination

              Paralytic ileus

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              Warnings

              Contraindications

              Hypersensitivity

              Angle-closure glaucoma

              Cautions

              Exacerbation of parkinsonism, neuroleptic malignant syndrome, and withdrawal symptoms associated with therapy discontinuation or dose reduction; drug should be withdrawn gradually

              Perform gonioscope evaluation before initiating treatment; monitor intraocular pressure closely at regular periodic intervals

              Therapy may impair memory and exacerbate cognitive deficits in the elderly; may also cause delirium, hallucinations, and confusion when administered at high doses

              Use extreme caution and monitor closely patients with liver, cardiac, kidney disorders, prostatic hyperplasia (urinary stricture), or with hypertension

              Drug has atropine-like properties; use with caution in patients with glaucoma, obstructive disease of the gastrointestinal or genitourinary tracts and in elderly males with prostatic hypertrophy

              Geriatric patients (>60 years) develop increased sensitivity to parasympathetic drugs; may precipitate incipient glaucoma in these patients

              Not for use in patients with tardive dyskinesia unless it exists concomitantly with Parkinson disease; therapy may potentially exacerbate symptoms of tardive dyskinesia

              May cause hyperthermia that can be fatal and anhidrosis; use with caution during exercise or hot weather, especially if administered concomitantly with anticholinergic agents to patients with CNS disease, alcoholics, or persons in a hot environment doing manual labor

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              Pregnancy & Lactation

              Pregnancy Category: C

              Lactation: no data; may inhibit lactation

              Pregnancy Categories

              A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

              B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

              C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

              D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

              X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

              NA: Information not available.

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              Pharmacology

              Mechanism of Action

              Trihexyphenidyl inhibits the parasympathetic nervous system and has a relaxing effect on smooth muscles

              Pharmacokinetics

              Half-Life elimination: 33 hr

              Onset: 1 hr

              Peak effects: 1.3 hr

              Duration: 6-12 hr

              Metabolism: Unknown

              Excretion: Urine and bile

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              Images

              BRAND FORM. UNIT PRICE PILL IMAGE
              trihexyphenidyl oral
              -
              5 mg tablet
              trihexyphenidyl oral
              -
              2 mg tablet
              trihexyphenidyl oral
              -
              5 mg tablet
              trihexyphenidyl oral
              -
              2 mg tablet
              trihexyphenidyl oral
              -
              0.4 mg/mL solution
              trihexyphenidyl oral
              -
              0.4 mg/mL solution
              trihexyphenidyl oral
              -
              5 mg tablet
              trihexyphenidyl oral
              -
              2 mg tablet

              Copyright © 2010 First DataBank, Inc.

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              Patient Handout

              Patient Education
              trihexyphenidyl oral

              TRIHEXYPHENIDYL - ORAL

              (try-hex-ee-FEH-nih-dill)

              COMMON BRAND NAME(S): Artane

              USES: Trihexyphenidyl is used to treat symptoms of Parkinson's disease or involuntary movements due to the side effects of certain psychiatric drugs (antipsychotics such as chlorpromazine/haloperidol). Trihexyphenidyl belongs to a class of medication called anticholinergics that work by blocking a certain natural substance (acetylcholine). This helps decrease muscle stiffness, sweating, and the production of saliva, and helps improve walking ability in people with Parkinson's disease.Anticholinergics can stop severe muscle spasms of the back, neck, and eyes that are sometimes caused by psychiatric drugs. It can also decrease other side effects such as muscle stiffness/rigidity (extrapyramidal signs-EPS). It is not helpful in treating movement problems caused by tardive dyskinesia and may worsen them.

              HOW TO USE: Take this medication by mouth, usually 3 to 4 times a day with meals and at bedtime, or as directed by your doctor. Your doctor may start you at a low dose and increase your dose slowly to find the best dose for you. The dosage is based on your medical condition, age, and response to therapy.If you are using the liquid form of this medication, measure your dose with a special measuring spoon or device. Do not use a household spoon because it may not provide the correct dose.Take this medication regularly in order to get the most benefit from it. To help you remember, take it at the same times each day.Take this medication at least 1 hour before antacids containing magnesium, aluminum, or calcium. Allow at least 1-2 hours between doses of trihexyphenidyl and certain drugs for diarrhea (adsorbent antidiarrheals such as kaolin, pectin, attapulgite). Take this medication at least 2 hours after ketoconazole. Antacids and some drugs for diarrhea may prevent the full absorption of trihexyphenidyl, and this product may prevent the complete absorption of ketoconazole when these products are taken together.If you are taking this medication for side effects from another medication, your doctor may instruct you to take it on a regular schedule or only as needed. If you are taking this medication for Parkinson's disease, your doctor may change the dose of your other medications (e.g., levodopa). Follow your doctor's instructions closely.Though it helps many people, this medication may sometimes cause addiction. This risk may be higher if you have a substance use disorder (such as overuse of or addiction to drugs/alcohol). Do not increase your dose, take it more often, or use it for a longer time than prescribed. Properly stop the medication when so directed. Some conditions may become worse when the drug is suddenly stopped. Your dose may need to be gradually decreased.When used for an extended period, this medication may not work as well and may require different dosing. Talk with your doctor if this medication stops working well. Inform your doctor if your condition persists or worsens.

              SIDE EFFECTS: Drowsiness, dizziness, constipation, flushing, nausea, nervousness, blurred vision, or dry mouth may occur. These effects usually lessen as your body gets used to the medicine. If any of these effects persist or worsen, contact your doctor or pharmacist promptly.To relieve dry mouth, suck on (sugarless) hard candy or ice chips, chew (sugarless) gum, drink water, or use a saliva substitute.Remember that this medication has been prescribed because your doctor has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.Tell your doctor right away if any of these unlikely but serious side effects occur: decreased sexual ability, severe stomach/abdominal pain, difficult/painful swallowing, difficulty urinating, weakness.Get medical help right away if you have any very serious side effects, including: chest pain, severe dizziness/fainting, high fever, fast/irregular/slow heartbeat, mental/mood changes (e.g., confusion, hallucinations, memory problems), eye pain/swelling/redness, vision changes (such as seeing rainbows around lights at night).A serious allergic reaction to this drug is unlikely, but seek immediate medical attention if it occurs. Symptoms of a serious allergic reaction include: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.In the US -Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

              PRECAUTIONS: Before taking trihexyphenidyl, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: personal or family history of glaucoma (angle-closure type), blockage of the bladder/esophagus/stomach/intestines (e.g., bowel obstruction), severe ulcerative colitis.Before using this medication, tell your doctor or pharmacist your medical history, especially of: breathing problems (e.g., asthma, emphysema), diarrhea caused by an infection, heart problems (e.g., angina, heart attack, heart failure, fast/irregular heartbeat), high/low blood pressure, intestinal problems (e.g., chronic constipation, ileus, ulcerative colitis), kidney disease, liver disease, mental/mood problems (e.g., anxiety, dementia, psychosis), certain muscle disease (myasthenia gravis), certain nerve disease (autonomic neuropathy), seizure, stomach problems (e.g., acid reflux, hiatal hernia, ulcer), stroke, overactive thyroid (hyperthyroidism), problems urinating (e.g., due to enlarged prostate, neurogenic bladder), personal or family history of a substance use disorder (such as overuse of or addiction to drugs/alcohol).This drug may make you dizzy or drowsy or blur your vision. Alcohol or marijuana (cannabis) can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness or clear vision until you can do it safely. Avoid alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).To minimize dizziness and lightheadedness, get up slowly when rising from a sitting or lying position.This medication decreases saliva production, an effect that can increase gum and tooth problems (e.g., cavities, gum disease). Take special care with your dental hygiene (e.g., brushing, flossing) and have regular dental check-ups.Liquid forms of this product may contain alcohol. Caution is advised if you have diabetes, alcohol dependence, or liver disease. Some medications (e.g., disulfiram, metronidazole) may cause a serious reaction when combined with alcohol. Tell your doctor if you are taking any medication that should not be used with alcohol. Ask your doctor or pharmacist about using this product safely.This drug can cause decreased sweating, which could cause a severe rise in your body temperature (hyperthermia). The risk of this serious side effect is greater in hot weather, during vigorous exercise, and/or if you drink alcohol. Drink plenty of fluids and dress lightly while in hot weather and when exercising. If you experience signs of hyperthermia such as mental/mood changes, headache, or dizziness, promptly seek cool or air-conditioned shelter and/or stop exercising, and seek immediate medical attention. Consult your doctor for more details.Older adults may be more sensitive to the side effects of this drug, especially dizziness, drowsiness, heatstroke, memory problems, difficulty urinating, and constipation. Dizziness and drowsiness can increase the risk of falling.Children may be more sensitive to the effects of this drug, especially effects on heart rate.During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.It is not known if this drug passes into breast milk. Consult your doctor before breast-feeding.

              DRUG INTERACTIONS: Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.This drug should not be used with the following medication because very serious interactions may occur: pramlintide.If you are currently using the medication listed above, tell your doctor or pharmacist before starting trihexyphenidyl.Before using this medication, tell your doctor or pharmacist of all prescription and nonprescription/herbal products you may use, especially: anticholinergics/antispasmodics (e.g., belladonna alkaloids, clidinium), certain antiarrhythmics (e.g., disopyramide, quinidine), corticosteroids (e.g., prednisone), MAO inhibitors (isocarboxazid, linezolid, metaxalone, methylene blue, moclobemide, phenelzine, procarbazine, rasagiline, safinamide, selegiline, tranylcypromine), motion sickness medication (e.g., meclizine, scopolamine), potassium tablets/capsules, tricyclic antidepressants (e.g., amitriptyline, doxepin).Tell your doctor or pharmacist if you are taking other products that cause drowsiness such as opioid pain or cough relievers (such as codeine, hydrocodone), alcohol, marijuana (cannabis), drugs for sleep or anxiety (such as alprazolam, lorazepam, zolpidem), muscle relaxants (such as carisoprodol, cyclobenzaprine), or antihistamines (such as cetirizine, diphenhydramine).Check the labels on all your medicines (such as allergy or cough-and-cold products) because they may contain ingredients that cause drowsiness. Ask your pharmacist about using those products safely.

              OVERDOSE: If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center. Symptoms of overdose may include: unusually fast/slow heartbeat, slow/shallow breathing, unconsciousness, seizures, loss of coordination, fever, hot/dry/flushed skin, widened pupils, change in vision, change in the amount of urine, confusion, hallucinations.

              NOTES: Do not share this medication with others.Laboratory and/or medical tests (e.g., eye exams) should be performed periodically to monitor your progress or check for side effects. Consult your doctor for more details.People with Parkinson's disease may have an increased risk for developing skin cancer (melanoma). If you are taking this drug to treat Parkinson's disease, tell your doctor promptly if you notice a change in the appearance or size of moles or other unusual skin changes. Ask your doctor if you should have regular skin exams.

              MISSED DOSE: If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up.

              STORAGE: Store at room temperature between 68-77 degrees F (20-25 degrees C) away from light and moisture. Do not store in the bathroom. Keep all medicines away from children and pets.Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company for more details about how to safely discard your product.

              Information last revised September 2021. Copyright(c) 2021 First Databank, Inc.

              IMPORTANT: HOW TO USE THIS INFORMATION: This is a summary and does NOT have all possible information about this product. This information does not assure that this product is safe, effective, or appropriate for you. This information is not individual medical advice and does not substitute for the advice of your health care professional. Always ask your health care professional for complete information about this product and your specific health needs.

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              Formulary

              FormularyPatient Discounts

              Adding plans allows you to compare formulary status to other drugs in the same class.

              To view formulary information first create a list of plans. Your list will be saved and can be edited at any time.

              Adding plans allows you to:

              • View the formulary and any restrictions for each plan.
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              • Access your plan list on any device – mobile or desktop.

              The above information is provided for general informational and educational purposes only. Individual plans may vary and formulary information changes. Contact the applicable plan provider for the most current information.

              Tier Description
              1 This drug is available at the lowest co-pay. Most commonly, these are generic drugs.
              2 This drug is available at a middle level co-pay. Most commonly, these are "preferred" (on formulary) brand drugs.
              3 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs.
              4 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
              5 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
              6 This drug is available at a higher level co-pay. Most commonly, these are "non-preferred" brand drugs or specialty prescription products.
              NC NOT COVERED – Drugs that are not covered by the plan.
              Code Definition
              PA Prior Authorization
              Drugs that require prior authorization. This restriction requires that specific clinical criteria be met prior to the approval of the prescription.
              QL Quantity Limits
              Drugs that have quantity limits associated with each prescription. This restriction typically limits the quantity of the drug that will be covered.
              ST Step Therapy
              Drugs that have step therapy associated with each prescription. This restriction typically requires that certain criteria be met prior to approval for the prescription.
              OR Other Restrictions
              Drugs that have restrictions other than prior authorization, quantity limits, and step therapy associated with each prescription.
              Additional Offers
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              Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.