An allergy is when your immune system reacts to something that’s normally harmless to most people. If you come into contact with a substance that your immune system views as a threat, called an allergen, it responds by releasing a chemical called histamine and other substances. The release of these substances is what causes your allergic reaction. There are many types of allergies. Some allergies are seasonal and others are year-round. Some allergies may be life-long. The following are the common types of allergies.
Food allergy is an unpleasant or dangerous immune system reaction after a certain food is eaten. Any food may cause an allergic reaction, but the most common causes are the proteins in cow’s milk, egg white, peanuts, tree nuts, fish, shellfish, wheat and soybeans. It’s sometimes difficult to determine which allergens are responsible for a food allergy, because reactions to foods are sometimes delayed. An allergic reaction to food usually occurs within five minutes to about half an hour of eating it. When people have food allergies, they are likely to have such symptoms as rash, vomiting, diarrhea, coughing, wheezing, facial swelling and hives.
The most common type of respiratory allergies is allergic rhinitis or nasal allergy. It is characterized by swelling and inflammation of nasal passages, congestion, sneezing, and itchy and watery eyes. It may be caused by breathing air that contains an allergen. Allergic rhinitis often begins around the age of two years, but commonly only surfaces in a person’s late teens or early 20s. Allergic rhinitis is usually seasonal and referred to as intermittent allergic rhinitis. Persistent allergic rhinitis occurs all year round and is sometimes referred to as “sinus”.
Another type of respiratory allergies is allergic asthma, which is an inflammation of the lungs and airways and constriction of the bronchial tubes. The main causes are environmental exposure and allergies to allergens such as pollen, mould spores, animal dander and dust mites. Asthma causes a recurrent tight chest, wheezing and/or coughing, which is usually prominent in the early hours of the morning.
One common type of skin allergies is atopic dermatitis or eczema. When people have eczema, they may have symptoms like dry, scaly skin appearing on red, inflamed areas; extreme itchiness, and a burning sensation. Children who have a family history of allergies are prone to eczema, and children who suffer from eczema are more likely to develop other allergies later in life.
Another common type of skin allergies is contact dermatitis. Just as its name implies, contact dermatitis is caused by contact with a natural substances and manufactured items that becomes an allergen. Common causes of contact dermatitis are acid and alkaline materials, including soaps and detergents; solvents, adhesives, and other industrial chemicals; poison ivy, oak or sumac; nickel and other metals used in jewelry; topical medications, including antibiotics and anesthetics; rubber; perfumes or cosmetics; fabrics such as wool and clothing made from such fabrics.
Obviously, drug allergies are an abnormal reaction of the immune system to certain medications, such as penicillin and other antibiotics, sulfa drugs, anti-seizure medications, aspirin and other painkillers, muscle relaxants and general anaesthetic agents used during anaesthesia, local anaesthetics, and dyes injected into the blood for X-ray purposes. Sometimes, drug allergies are also called “medicine allergies”.
This type of allergies referred to allergies caused by insect stings or bites from wasps, bees, mosquitoes, fire ants, fleas, horseflies, black flies, and other insects.
Latex allergies are an allergic reaction to certain proteins found in natural rubber latex or the manmade material latex. They may cause such symptoms as asthma, itching and rash, hives, watery eyes, and anaphylaxis.