Allergy terms

Adenoids: Glands or lymphoid tissue in the upper part of the throat, behind the nose.

Adenoidectomy: The surgical removal of adenoids that may help prevent blockage of the nasal passageways and eustachian tubes. This may help to reduce recurrent sinus and ear infections, among other conditions. This is usually done as a day case procedure under general anaesthesia.

Adrenaline: A medication used to treat severe allergic reactions, such as anaphylactic shock. It is available in a self-injectable form or can be injected by a medical professional.

Allergen: A substance that your body perceives as dangerous and that triggers an allergic reaction.

Allergic rhinitis: A condition whereby an allergen triggers an allergic reaction resulting in nasal swelling and inflammation. Hayfever (pollen allergy) is a type of allergic rhinitis, other forms of allergic rhinitis may be caused by house dust mites or pet dander.

Allergy: An exaggerated response to a substance or condition produced by the release of histamine or histamine-like substances from specific cells in the body.

Allergy injections: See Immunotherapy

Anaphylaxis: Severe, life-threatening allergic response that may include lowered blood pressure, swelling and hives.

Angioedema: Swelling similar to urticaria (hives), but the swelling occurs beneath the skin instead of on the surface. Angioedema is characterised by deep swelling around the eyes and lips and sometimes of the hands and feet.

Antibodies: Specialised proteins produced by lymphoid cells (B cells) that circulate in the blood. Antibodies seek and attach to foreign proteins, micro-organisms or toxins in order to neutralise them. They are part of the immune system.

Antigen: A substance, usually a protein, which the body perceives as foreign.

Antihistamine: Medication that prevents symptoms of congestion, sneezing and an itchy, runny nose by blocking histamine receptors.

Anti-inflammatory: A type of medication that reduces swelling and inflammation.

Asthma: A disease of the airways in the lungs (bronchial tubes) that carry air in and out of the lungs. Asthma causes the airways to narrow, the lining of the airways to swell, and the cells that line the airways to produce more mucus. These changes make breathing difficult and cause a feeling of not getting enough air into the lungs.

Bronchodilators: Medications used to relax the muscle bands that tighten around the airways during an asthma episode. Bronchodilators also help clear mucus from the lungs.

Conjunctivitis: An inflammation of the conjunctiva, the tissue that lines the inside of the eyelid.

Dander, animal: Tiny scales shed from animal skin or hair. Dander floats in the air, settles on surfaces and makes up much of household dust. Pet dander is a classic cause of allergic reactions.

Decongestant: Medication that shrinks swollen nasal tissues to relieve symptoms of nasal swelling, congestion and mucus secretion.

Dermatitis: Inflammation of the skin, either due to direct contact with an irritating substance or due to an allergic reaction. Symptoms include redness, itching and sometimes blistering.