When the body reacts in an abnormal manner to certain foreign substances called allergens, an allergic reaction occurs. Several symptoms like itching, runny nose, watery eyes and red eyes are experienced due to this reaction. Allergens can include peanuts, ragweed, pets, medicines, dust, pollen, and food substances. Some of the most common allergens are airborne-pollen and dust mites.
Airborne Allergens
Allergens are light particles that float in the air and are not visible to the naked eye. We come in contact with them mostly through inhalation. As a person inhales, the particles enter the lungs through the nose and can cause allergic rhinitis or asthma. Some of them also come in contact with the skin and cause atopic dermatitis, urticaria or allergic conjunctivitis.
Pollen
These are the most common airborne allergens. Unlike popular belief, allergic pollen is not present in bright yellow flowers but is instead found in innocuous rare plants. The main sources of the allergic pollen are grasses, weeds and trees.
• Grasses - Bermuda grass, orchard grass, Kentucky grass, and rye grass
• Trees - Olive, cypress, chestnut, oak, maple, walnut etc
• Weeds - Ragweed is the main cause followed by plantain, mugwort and others
Pollen allergy is limited to a particular season of the year as specific to the plant.
Molds
The allergy is caused by mold spores which are small particles released by fungi into the air. They can be easily inhaled and taken to the lungs. This often causes asthma along with rhinitis and allergic conjunctivitis.
House Dust Mites
This can be a combination of different harmful allergens like dust mites, insects, fungi and animal dander. These allergens primarily cause respiratory disease (asthma and rhinitis) when they enter the bronchi through inhalation. They can also cause allergic conjunctivitis and atopic dermatitis.
Animal Allergens
This is very common source of allergy usually found in dogs, cats, and guinea pigs. These allergens are said to be found in the animal’s secretions - saliva and skin of cats and dogs. For other animals like guinea pigs and rabbits it is found in their sweat, urine or feces. The allergen can pass on to the humans through skin contact or through inhalation of the particles floating in the air.
Food Allergens
• Allergy is commonly seen in children when they consume milk, eggs, peanuts or cereals and in adults when they consume legumes, soy, beans, fish, fruits and nuts.
• Raw and cooked foods can be carriers of allergens.
• Food allergy can also arise in some people who are sensitive to air borne allergens. They should allergic reactions to plant derived foods with symptoms like throat, lip and tongue itch, swelling, rashes etc.
Insect Allergens
A bee sting carries a venom sac which can leave a stinger on the skin. This can cause pain, swelling and redness around that area. If it is an allergic reaction the person requires medical attention. This can be characterized with difficulty in breathing, swelling of throat, face or mouth, wheezing, anxiety, quick pulse, dizziness, swallowing difficulty and low blood pressure. A repeat sting can be life-threatening.
Contact Allergens
This allergy is caused by reaction to a chemical used everyday. Cosmetics like deodorants, sprays, soaps, creams, dyes, perfumes etc can cause allergic reactions. The symptoms seen are allergic rhinitis and skin eczema.
Latex allergy occurs due to contact with rubber during work or surgical procedures usually through rubber gloves and other things like erasers, clothing, elastic bands, balloons, dental devices etc. Eye irritation, rashes, hives, itching, wheezing are some of the symptoms of this allergy.
Metals such as chromium, nickel and cobalt can also cause allergy. They usually cause respiratory disorders and contact allergy such as eczema.
Drug Allergens
Certain drugs can also be the causative factors for an allergy. The main ingredient or a non-active ingredient may be the allergens. Sometimes allergy can also be from the preservatives added to maintain the shelf life of the drug. Some of the known drugs that are potential allergens are antibiotics like penicillin, anti tetanus and anti diphtheria serums, aspirin and insulin.