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All About Allergies: Be Ready for Spring
Praveen Buddiga, MD | April 24, 2023
| Contributor Information
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Image courtesy of Wikimedia Commons / BruceBlaus. Blausen.com staff. Medical gallery of Blausen Medical 2014. WikiJournal of Medicine. 1(2).
All About Allergies: Be Ready for Spring
Praveen Buddiga, MD | April 24, 2023 | Contributor Information
In 2021, 25.7% of US adults had a diagnosed seasonal allergy.[1] Spring allergies are triggered as trees start blooming and billions of pollen grains are released into the air, causing susceptible individuals to develop allergic rhinitis (hay fever).[2-6] In these patients, the pollen causes degranulation of mast cells, which contain inflammatory mediators (histamine and other allergy-causing chemicals). This process is clinically represented by the following:
Red, watery, itchy eyes ("allergic shiners," or periorbital edema, may also develop)
Sneezing
Runny nose
Postnasal drip
Itchy, scratchy throat
Sinus headaches
Feelings of sinus fullness
In addition to these symptoms, inflammatory mediators lead to swelling and hypertrophy of the nasal turbinates, as well as to possible loss of taste and smell.[7,8]
Pollen can also trigger asthma attacks, with inflammatory mediators from degranulated mast cells causing airway inflammation, bronchial hyperresponsiveness, and airflow obstruction—the last being a consequence of factors such as acute bronchoconstriction, airway edema, and mucous plug formation.[9]
Image courtesy of Wikimedia Commons / katsrcool.
All About Allergies: Be Ready for Spring
Praveen Buddiga, MD | April 24, 2023 | Contributor Information
Tree pollen typically is the primary culprit in spring allergies, being airborne between the start of February and mid-June in some parts of the United States.[10] However, the timing of pollen spread varies geographically, depending on a region's weather, winter climate, drought patterns, and tree species. In Central California, for example, olive tree pollen is highly active in late March and early April. The infamous cedar fever, caused by pollen from the mountain cedar (Juniperus ashei; shown) occurs in Central Texas during December and January, though in some cases it may encroach into March. American elm pollinates in the spring, but several species of elm pollinate in the fall.
Image courtesy of Dreamstime / Vbaleha.
All About Allergies: Be Ready for Spring
Praveen Buddiga, MD | April 24, 2023 | Contributor Information
Pollen initiates an allergic reaction only in persons with allergic antibodies (immunoglobulin E [IgE]) specific to that pollen. Mast cells in the nasal and respiratory passages, sinuses, throat, and eyes are sensitized with IgE, ultimately releasing histamine and other inflammatory mediators, which cause sneezing, coughing, wheezing, and tearing of the eyes.[7,8] The use of oral antihistamines, corticosteroid and antihistamine nasal sprays, inhalant corticosteroids, and antihistamine and mast-cell stabilizer eye drops may help mitigate these symptoms.[11]
Family history plays a significant role in an individual's predisposition to allergies. If one parent has allergies, then it is likely that at least one of multiple children will also have them; the likelihood is greater if allergies affect both parents.
Image courtesy of Wikimedia Commons / Doc. RNDr. Josef Reischig, CSc.
All About Allergies: Be Ready for Spring
Praveen Buddiga, MD | April 24, 2023 | Contributor Information
The predominant types of allergens vary according to the season, though there may be some carryover from one season to the next. Global warming and climate change are also now affecting which allergens occur at specific times of the year. Moreover, rising temperatures lengthen the period for pollen release,[12] with greater pollen exposure expected to cause more allergy cases and with pollen counts possibly more than doubling from their 2012 values by 2040.[13]
As mentioned, trees pollinate from late winter to late spring; thus, tree pollen is the predominant cause of early spring allergies. Spring pollinators include the following[14,15]:
Birch
Beech
Ash
Cedar
Olive
Juniper
Sycamore
Red alder
Oak
Pine (pollen grains are shown in the slide)
Poplar
Cottonwood
Hickory
Box elder
Maple
Image courtesy of Wikimedia Commons / H Zell.
All About Allergies: Be Ready for Spring
Praveen Buddiga, MD | April 24, 2023 | Contributor Information
Grasses pollinate during late spring and summer. The major grass types throughout the United States include the following[15,16]:
Bermuda
Bahia
Johnson
Rye
Orchard
Fescue
Kentucky bluegrass
Redtop
Sweet vernal
Timothy (shown)
Images courtesy of Wikimedia Commons / Matt Lavin (top left), Nigel Cattlin / Science Source (top middle), Gilbert S Grant / Science Source (right), Wikimedia Commons / Geoff Gallice (bottom left), and Dennis Kunkel Microscopy / Science Source (bottom middle).
All About Allergies: Be Ready for Spring
Praveen Buddiga, MD | April 24, 2023 | Contributor Information
Weeds pollinate during late summer and fall. The most prominent weed in the United States, making up about 75% of the weed burden, is ragweed (Ambrosia artemisiifolia). One ragweed plant is able to produce up to 1 billion pollen grains. Other weeds that cause allergy symptoms by releasing pollen into the air include the following[15]:
Lamb's quarters
Pigweed
Russian thistle
Sagebrush
Cocklebur
Plantain
Mugwort
Image courtesy of Wikimedia Commons / Jon Houseman and Matthew Ford.
All About Allergies: Be Ready for Spring
Praveen Buddiga, MD | April 24, 2023 | Contributor Information
Most molds, whose habitats include rotting logs and fallen leaves, do not follow a clear seasonal pattern for allergen dispersal. They are primarily dependent on weather patterns to release their spores, with some needing dry, breezy weather and others requiring high humidity and the resulting fog or dew. The major types of allergy-causing molds include the following[17]:
Alternaria
Cladosporium
Penicillium
Aspergillus
Epicoccum
Fusarium
Mucor
Rhizopus (sporangia, the mold's spore-bearing structures, are shown in the slide)
Images courtesy of Wikimedia Commons / Herakrieger.
All About Allergies: Be Ready for Spring
Praveen Buddiga, MD | April 24, 2023 | Contributor Information
Allergic conjunctivitis (shown) is characterized by irritation and redness of the eyes and is common in allergy season. Like the nasal mucosa, the conjunctiva of the eye is a mucosal surface; consequently, pollen and other allergens that trigger allergic rhinitis can also cause allergic conjunctivitis. Contact between an allergen (eg, pollen) and the eyes causes ocular mast cells to release inflammatory mediators, including histamine, a reaction that can be prevented by using eye drops containing antihistamines, mast-cell stabilizers, or both (dual-action eye drops). Antihistamines used in eye drops include olopatadine, ketotifen, epinastine, cetirizine, azelastine, alcaftadine, and bepotastine; mast-cell stabilizers used in eye drops include cromolyn, pemirolast, lodoxamide, nedocromil, and bepotastine.[18,19]
Image courtesy of Medscape.
All About Allergies: Be Ready for Spring
Praveen Buddiga, MD | April 24, 2023 | Contributor Information
A cold can often be differentiated from an allergy on the basis of the length and timing of symptoms. A cold, commonly caused by a rhinovirus, usually lasts 7-10 days. If symptoms continue beyond 10 days and become recurrent, an allergic condition may be present. Allergy is also indicated if symptoms recur at the same time every year.
Despite similarities in presentation, asthma and bronchitis can be differentiated clinically. In asthma, chest radiography may show hyperinflated lungs, whereas physical examination may reveal wheezing caused by airway narrowing that inhibits expiratory air flow. Symptoms also include cough and chest tightness or "congestion." The high-resolution computed tomography (CT) scan in the slide, obtained during expiration in a patient with asthma, reveals a mosaic pattern of lung attenuation. Lucent portions (arrows) demonstrate areas of air-trapping.
Bronchitis is an inflammation of the bronchial tubes. Mucus buildup interferes with the movement of air into and out of the lungs, and wheezing, coughing, and sputum production may occur. The cause of bronchitis can be bacterial or viral.
Image courtesy of Medscape.
All About Allergies: Be Ready for Spring
Praveen Buddiga, MD | April 24, 2023 | Contributor Information
Inadequate treatment can result in complications. Allergic rhinitis, for example, can lead to the following[4,5]:
Chronic or acute sinusitis – This can result when the inflamed nasal turbinates block the natural drainage of the sinuses through the ostiomeatal complex
Otitis media – This is believed to occur when inflamed nasal passages interfere with the patency of the eustachian tube
Sleep disturbance
Chronic fatigue
Headache
Throat irritation
There is also evidence that allergic rhinitis, if not controlled, can worsen inflammation related to asthma.[20]
In the case of acute otitis media shown in the slide, a purulent effusion exists behind a bulging tympanic membrane.
Image courtesy of Wikimedia Commons / National Institutes of Health (NIH).
All About Allergies: Be Ready for Spring
Praveen Buddiga, MD | April 24, 2023 | Contributor Information
The skin-prick method (shown) is used to test for antigens (eg, from trees, grass, weeds, dust mites, cat or dog dander, and mold). The test elicits a wheal-and-flare response if the patient is allergic to a specific allergen. Allergy results may also be derived by extracting blood and running a radioallergosorbent test (RAST) or an ImmunoCAP test for IgE, but it takes a few days to obtain results from these studies.
Praveen Buddiga, MD | April 24, 2023 | Contributor Information
Decisions by the US Food and Drug Administration (FDA) to permit over-the-counter (OTC) use of second-generation antihistamines (commonly referred to as nonsedating antihistamines, though sedation may occur in some patients) and nasal corticosteroids have increased the OTC options for allergy symptom control. Available OTC second-generation antihistamines include the following[11]:
Fexofenadine
Loratadine
Cetirizine
Levocetirizine
OTC nasal corticosteroids include fluticasone, mometasone, and triamcinolone; OTC nasal antihistamines include azelastine.
Images courtesy of Wikimedia Commons: Jynto (left), NEUROtiker (right).
All About Allergies: Be Ready for Spring
Praveen Buddiga, MD | April 24, 2023 | Contributor Information
Allergy symptoms can also be managed with nasal decongestants. Patients should be warned, however, that nasal decongestant sprays (ie, topical vasoconstrictive medications), such as those containing oxymetazoline, can cause inflammation, rhinitis medicamentosa, and bleeding.[21]
The decongestant pseudoephedrine can be taken orally but tends to increase blood pressure; it should therefore be used with care if high blood pressure is a problem.
Nasal sinus irrigation with physiologic saline, placed in a plastic syringe or plastic rinse bottle, can also aid sinus drainage.
Image courtesy of Medscape.
All About Allergies: Be Ready for Spring
Praveen Buddiga, MD | April 24, 2023 | Contributor Information
Allergy shot immunotherapy can reduce sensitivity to allergens.[22,23] Initially, patients receive injections of a gradually increasing dose of allergens, which builds up to a maintenance dose. The injected allergens are believed to elicit a protective immune response by increasing levels of IgG4 and regulatory T cells. This allows the immune system to respond to an environmental allergen rapidly and aggressively enough to prevent the activation of an allergic cascade of events. A course of allergy shots takes 3-5 years.
The most important potential side effect of this therapy is an anaphylactic event. Consequently, after receiving an allergy shot, patients are required to remain under observation in the physician's office for 30 minutes.
Sublingual immunotherapy (SLIT), in which the allergen is placed in tablet form under the tongue, is believed to be nearly as effective as allergy shot therapy. In 2014, the first SLIT drug, Oralair, received FDA approval for use against multiple grass pollens (sweet vernal, orchard, timothy, Kentucky bluegrass, and perennial rye).[24] Additional SLIT products have since been approved.[11,25]
Image courtesy of Medscape.
All About Allergies: Be Ready for Spring
Praveen Buddiga, MD | April 24, 2023 | Contributor Information
Allergy prevention measures include the following:
Limiting exposure to pollen and other allergens by remaining indoors on days when the pollen count is high or air quality is poor
Keeping windows closed during the morning; pollen counts tend to be high at this time of day
When driving, putting the car's ventilation in recirculation mode or using the air conditioner, which can limit the amount of pollen inside the car
A swollen, boggy nasal turbinate, a common finding in allergic rhinitis, is shown in the slide.[6]
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Contributor Information
Author
Praveen Buddiga, MD
CEO, Family Allergy Asthma Clinic
Fresno-Clovis, CA
Disclosure: Praveen Buddiga, MD, has disclosed the following
relevant financial relationships:
Serve(d) as a director, officer, partner, employee, advisor,
consultant, or trustee for: Family Allergy Asthma Clinic
Serve(d) as a speaker or member of a speakers bureau for: Teva
Pharmaceutical Industries, Ltd
Has a 5% or greater equity interest in: Family Allergy Asthma Clinic
Received income in an amount equal to or greater than $250 from:
Family Allergy Asthma Clinic
Reviewer
Bhumika Patel, MD
Chief Fellow
Division of Allergy and Immunology
Johns Hopkins All Children's Hospital
University of South Florida Morsani College of Medicine
Tampa, FL
Disclosure: Bhumika Patel, MD, has disclosed no relevant financial
relationships.
Nguyen QA. Allergic rhinitis in otolaryngology and facial plastic surgery. Medscape Drugs & Diseases. January 26, 2023; Accessed: April 21, 2023. Available at: http://emedicine.medscape.com/article/834281-overview.
Barnes KC. An update on the genetics of atopic dermatitis: scratching the surface in 2009. J Allergy Clin Immunol. 2010 Jan;125(1):16-29. PMID: 20109730
Greenhawt M et al. Sublingual immunotherapy: A focused allergen immunotherapy practice parameter update. Ann Allergy Asthma Immunol. 2017 Mar;118(3):276-82. PMID: 28284533
Brown T. FDA OKs Oralair, first US sublingual allergy immunotherapy. Medscape Medical News. April 2, 2014; Accessed: April 21, 2023. Available at: http://www.medscape.com/viewarticle/822975.
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