Allergy is hyperresponsiveness to simple triggers – these substances – known as ‘allergens’ initiate an immune response from the host with the release of certain chemicals that cause the typical symptoms of allergies.

Exposure to a harmless substance like a flowering plant or a smell can cause the immune system in the body to release antibodies. These antibodies act on cells to produce histamine and other chemicals which mediate the allergy response in the body.

Allergies usually start in early childhood – like some pollen allergy, some food allergies like lactose, gluten, peanut, etc.

Some allergies start later in life and are adult-onset allergies – typically allergic rhinitis and asthma.

Childhood allergies also sometimes progress to allergies in adulthood.

The two main types of Allergens by route of admission are –

INHALANTS- substances that we take in through our nose- these cause nasal symptoms (sneezing, watering, nasal stuffiness) or symptoms in the lungs ( wheezing, cough, breathing difficulties).
INGESTANTS – substances that we eat or drink- that is we take them through the oral route. They usually cause stomach upset, abdominal pain, bloating, gaseousness, but can sometimes produce serious and life-threatening symptoms like sudden choking or breathing difficulty (angioneurotic oedema) – this can happen with peanut and some other food allergies.
Currently, there is no cure for allergies – there is a lot of promising research in the pipeline.

Some allergies can reduce/disappear over time –

Some children get over their lactose/ gluten allergy over time. Lactose intolerance can also be temporarily acquired during intestinal infection. However, peanut allergies usually sustain themselves over time.
Some allergens like pollen etc may become less potent over time
Repeated exposure to small doses of an allergen can sometimes cause desensitization
Medical therapy- Immunotherapy can modify the body’s response to an allergen – again by the mechanism of desensitization.
Many OTC and prescription medications can alleviate allergy symptoms.

You must visit a medical facility urgently in case of

choking sensation
breathing difficulty, wheezing
lightheadedness/ sudden fall in blood pressure
losing consciousness