Causes of Allergy: Why the Body Overreacts

Causes of Allergy: Why the Body Overreacts

An allergy is a case of mistaken identity: the immune system flags a harmless substance - pollen, dust, a food, a medicine - as dangerous and launches a defence. The sneezing, itching, and swelling are that defence, not the substance itself.

The Mechanism in Brief

• First contact (sensitisation): the immune system meets the allergen and produces IgE antibodies against it. No symptoms yet.
• Later contacts: IgE triggers mast cells to release histamine and other chemicals - causing itching, sneezing, wheals, wheeze, or worse.
• Why some people: heredity is the biggest driver (the "atopic" tendency running in families), alongside early-life exposures, environment, and gut health.

Common Triggers

• Airborne: house dust mites, pollen, mould, animal dander
• Foods: milk, eggs, peanuts, tree nuts, wheat, soy, fish, shellfish
• Skin contact: metals (nickel), cosmetics, latex, plants
• Stings and drugs: bee/wasp venom, certain antibiotics and painkillers

Risk also rises with eczema, asthma, or hay fever already in the family - the three travel together, per NHS allergies guidance.

The Classical View of Causes

Ayurveda's explanation for why one body overreacts and another does not centres on two ideas:

• Viruddhahara (incompatible food): Madhava Nidana and Charaka list faulty food combinations - milk with fish or sour fruit, for instance - and unsuitable diet-weather mismatches as prime causes of Sheetapitta, Udarda, and Kotha (the urticaria group)
• Ama (metabolic residue): incomplete digestion leaves a sticky, toxin-like residue that circulates, irritates tissues, and turns the immune response "sticky" - Kotha is explicitly blamed on suppressed vomiting and acute Ama

Add Asatmya - the classical word for "not suited to this particular body" - and the classical model reads as an early language for individual hypersensitivity. These are interpretive frameworks from a pre-immunology era; the IgE mechanism above is the operative science. But the classical instincts - watch food combinations, keep digestion clean, note personal idiosyncrasy - remain sensible household hygiene.

Frequently Asked Questions

Can you develop an allergy as an adult? Yes. Sensitisation can happen at any age - adult-onset food and drug allergies are well documented.

Are allergies inherited? The tendency (atopy) is inherited; the specific allergy is not. Two allergic parents raise a child's risk substantially.

Does pollution cause allergies? Air pollution irritates airways and amplifies allergic rhinitis and asthma, though it is an amplifier more than a root cause.

Does Ayurveda blame "weak digestion" for allergies? Broadly, yes - Ama from impaired digestion is the classical root. In practice the dietary discipline this implies (regular meals, compatible foods) does help many patients, even if the mechanism is described differently today.