I take notice of the tree buds and the sprouting of the daffodils in April. This nature tour is a preparation for the spring pollen season, otherwise known as the “God Bless You” season.
Allergy treatments go back to 3000 BC, as mentioned in a book called Ancestors of Allergy. Sometime before 79 AD, Pliny the Elder wrote the first encyclopedia-like text which identified pollen as a cause of respiratory conditions. Around 1600, “summer asthma” and in 1700, “hay fever” became descriptors for seasonal allergies. The first diagnosis of allergy-related respiratory symptoms was in 1906.
Dr. Daniel Bovet discovered the first antihistamine in 1937, called pyrilamine. Dr. Bovet went on to win the Nobel Prize in Medicine in 1947 for his discovery of antihistamines, sulfa drugs, and muscle relaxants. In 1948 doctors Philip Hench and Edward Kendall discovered corticosteroids. Corticosteroids are anti-inflammatory medications administered for allergic reactions and asthma. In November 1982, Professor Bengt Samuelsson, Sune Bergström, and Sir John Vane were awarded the Nobel Prize in Physiology or Medicine for discovering leukotrienes. Leukotrienes are substances in the body that cause bronchoconstriction (narrowing of the bronchioles in the lungs) and inflammation of the lung tissue. Leukotrienes production increases upon inhalation of an allergen, causing an allergic reaction.
An allergy is a hypersensitivity immune response to normally harmless substances, such as pollens or foods. However, in allergic individuals, the immune system identifies them as a threat and produces an abnormal response (World Allergy Organization. White Book on Allergy (WAO). 2011). Many ordinary substances may trigger an allergic reaction. Mast cells will produce leukotrienes that may cause bronchoconstriction and inflammation.
The next step of the allergic process comes after the allergen enters the body. Suppose the same allergen enters the body through exposure to food, pollen, and dander. The immune globulin E (IgE) antibody will attach to the allergen and cause the mast cells to produce histamine and leukotrienes. This process leads to the allergy symptoms of sneezing, runny nose, congestion, hives, and swelling of the lips, tongue, and throat (anaphylactic reaction). An anaphylactic reaction is rare and can cause loss of consciousness, drop in blood pressure, and severe shortness of breath. Emergency administration of epinephrine (EpiPen®) is necessary to stop the closing of the throat with loss of respiration.
There are also four different types of allergic reactions. Type I or anaphylactic reactions cause the exacerbation of bronchial asthma, allergic rhinitis, allergic dermatitis, food allergies, and anaphylaxis. Type II or cytotoxic reactions cause autoimmune hemolytic anemia (the body sees red blood cells as foreign and attacks them, leading to anemia), immune thrombocytopenia (decreased platelets due to immune complexes), and autoimmune neutropenia (low white blood cells that are seen as foreign and attacked). Type III or immunocomplex reactions cause lupus (immune system attacks the body tissues), serum sickness (similar to an allergy and the body attacks medicines used for immune diseases), and arthus reaction (deposition of antigen/antibody complexes deposited in vascular walls).
The four major types of allergies based on the offending allergen are food, indoor environmental, allergic asthma, and seasonal allergies. Food allergies include eggs, milk, peanuts, fish, shellfish, fruits, vegetables, and wheat. Indoor allergies include dander, dust mites, cockroaches, and mold. Ten to thirty percent of the people in the world have seasonal allergies.
Treatments for seasonal allergies fall into five categories: nasal corticosteroid sprays, antihistamines, decongestants, mast cell stabilizers, and selective leukotriene receptor antagonists. The antihistamine doses come in tablets, capsules, and sprays. The selective leukotriene receptor antagonist is available in tablet form. There are also antihistamine ophthalmic solutions for eye itchiness caused by allergens.
Antihistamines are the most commonly used treatments for seasonal allergies. The mechanism of action is what the category implies. There are four histamine receptors in the body. The histamine receptor most affected by allergens is the H1 receptor. By antagonizing the H1 receptor, the histamine release is physiologically blocked. The symptoms of seasonal allergies of runny nose, congestion, itchy eyes, and cough can be markedly decreased.
Most people are familiar with the antihistamine diphenhydramine (Benadryl®). Diphenhydramine is a first-generation antihistamine. After an accident, the most common over-the-counter drug found in pilots is diphenhydramine. Diphenhydramine could take up to 60 hours to be eliminated from the body. I cannot emphasize enough that the drowsiness caused by diphenhydramine is high. My recommendation is not to use diphenhydramine for seasonal allergies. Azatadine (Trinalin®) and cyproheptadine (Periactin®) are antihistamines that require a 24-hour wait to fly after the last dose. Two other NO FLY antihistamines on the market are meclizine (Antivert®) and hydroxyzine (Atarax®).
The second generation, non-sedating antihistamines are the medications of choice for the pilot. FAA-accepted, second-generation antihistamines are fexofenadine (Allegra®), fexofenadine/pseudoephedrine (Allegra-D®), loratadine (Claritin®), desloratadine (Clarinex®), and cetirizine (Zyrtec®). There is a 24-hour wait to fly after the last dose taken of Cetirizine.
Corticosteroid nose sprays are more efficacious than antihistamines for seasonal allergies. The study concluded that as-needed intranasal corticosteroids reduce allergic inflammation and are more effective than as-needed H1 receptor antagonists (antihistamines) in treating seasonal allergic rhinitis (Arch Intern Med. 2001;161(21):2581-2587). Corticosteroid sprays decrease the inflammatory response in the nose lining and conjunctiva of the eyes. Corticosteroid nose sprays reduce inflammation quickly when delivered via the nasal cavity. Two corticosteroid nasal sprays are widely available over-the-counter, including fluticasone (Flonase®) and mometasone (Nasacort®).
Two unique treatments for allergic rhinitis are cromolyn sodium (Nasalcrom®) and montelukast (Singulair®). Cromolyn sodium is a mast cell stabilizer whose mechanism of action is to prevent the release of histamine and leukotrienes and decrease hay fever symptoms and allergic rhinitis. As the medication class describes, montelukast (Singulair®) is a selective leukotriene receptor antagonist that blocks leukotriene production.
Decongestants are an allergy treatment administered for congestion in seasonal allergies. Pseudoephedrine is used in conjunction with non-sedating antihistamines (fexofenadine/pseudoephedrine) or alone as a decongestant. As mentioned in a previous article, pseudoephedrine may give a false positive urine test for amphetamine. Oxymetazoline (Afrin®) nasal spray is another choice as a decongestant. After three to four days of use, symptom relief decreases and leads to rebound congestion.As I continue my walks through the neighborhood and enjoy the splendor of mother nature, I also look to the sky and hope that my fellow pilots are symptom-free from their allergies. Prevention and symptom relief are the mainstays of this allergy season. Benjamin Franklin said it best in 1736, “An ounce of prevention is worth a pound of cure.” In our case, a tablet, capsule, or spray may prevent allergy pilots from having to interrupt a flight with a sneeze. Be well and safe.