According to the National Institute of Environmental Health, allergens are identified as a foreign substance that the body's immune system overreacts to, that are normally harmless in most people. Allergens sensitizes one immune system, exacerbates an allergic response and may trigger allergic asthma.
There are many classes of allergens, of which most allergens are proteins, including:
- Animal materials (like cat or dog hair/fur, roach, dust mite)
- Foods like peanuts, eggs, fruit and wheat
- Mold, fungal spores, house-dust mites and particles
- Insect venom, spider bites, mosquito bites and bees stings
- Seasonal pollen derived from certain trees/plants (The size of pollen determines the severity of one’s allergic response/reaction)
- Chemicals, drugs, and biological products (enzymatic protein cleaners and powder detergents)
According to the National Library of Medicine, an allergic response is dependent on the route of exposure. If one is exposed to an aeroallergen (by inhaling the allergen), the allergic response would lead to a respiratory reaction. If one is exposed to an allergen by ingesting or injecting an allergen, the allergic response would lead to gastrointestinal, cutaneous, or anaphylactic reactions.
How a person reacts to an allergen depends on how they come in contact with it. In many people, allergic reactions occur on the skin, in the airways and mucous membranes.
Symptoms can be mild or a real nuisance with a significant effect on everyday life. Inflammation, an immune system response to internal or external factors such as allergens, can be helpful or damaging.
Asthma is a chronic lung disease and some allergens can increase the severity of asthma symptoms in people who are sensitive to them. Symptoms include coughing, wheezing, chest tightness, or shortness of breath. During an asthma attack, the sides of the airways in lungs become inflamed, shrinking the airways which makes it harder to breathe. Severe asthma attacks can be life-threatening and may require emergency room visits and hospitalizations.
Resources:
1. Shah R, Grammer LC. Chapter 1: an overview of allergens. Allergy Asthma Proc. 2012 May-Jun;33 Suppl 1:2-5. doi: 10.2500/aap.2012.33.3531. PMID: 22794674.
2. U.S. Department of Health and Human Services. (n.d.). Allergens. National Institute of Environmental Health Sciences. https://www.niehs.nih.gov/health/topics/agents/allergens#:~:text=Introduction,biologic%20products%2C%20and%20insect%20venoms.
3. U.S. Department of Health and Human Services. (n.d.-b). Asthma. National Institute of Environmental Health Sciences. https://www.niehs.nih.gov/health/topics/conditions/asthma