Over 20% of the UK population has at least one allergy, and the numbers are increasing. Yet allergy — one of the most common chronic conditions — is frequently misunderstood and poorly managed. This guide covers the fundamentals.

The Immune Mechanism Behind Allergies

An allergic reaction is an inappropriate immune response to a harmless substance (allergen). On first exposure, the immune system produces IgE antibodies specific to the allergen. These IgE antibodies bind to mast cells and basophils throughout the body. On re-exposure, the allergen cross-links these IgE antibodies, triggering the mast cells to release histamine and other inflammatory mediators — causing the familiar symptoms of allergy: itching, sneezing, runny nose, watery eyes, rash, and (in severe cases) anaphylaxis.

Types of Allergy

Seasonal allergic rhinitis (hayfever) — triggered by tree pollen (spring), grass pollen (early summer) or weed/mould spores (late summer/autumn). Affects around 1 in 5 people in the UK. Perennial allergic rhinitis — year-round symptoms, typically triggered by house dust mites, pet dander (cats, dogs), mould or cockroaches. Allergic conjunctivitis — often accompanies rhinitis. Allergic asthma — airway inflammation and bronchoconstriction triggered by allergens. Food allergy — the most common triggers in the UK are peanuts, tree nuts, milk, egg, wheat, soy, sesame, fish and shellfish. Drug allergy — most commonly penicillin antibiotics; NSAID hypersensitivity also common. Contact dermatitis — delayed-type hypersensitivity to nickel, fragrances, preservatives or rubber.

OTC Allergy Treatment

Second-generation antihistamines — cetirizine (Zirtek), loratadine (Clarityn), fexofenadine (Allevia) — are the cornerstone of OTC allergy treatment. Once-daily, non-sedating (or minimally so). Start before the allergy season begins. Compare: cetirizine is the most studied and widely available; loratadine is truly non-sedating; fexofenadine has fewest CNS effects and is preferred when operating machinery. Nasal corticosteroid sprays — more effective than antihistamines alone for nasal symptoms. Now available OTC (fluticasone furoate: Pirinase). Use daily throughout the season; start 2 weeks before expected symptom onset. Sodium cromoglicate eye drops (Opticrom) — for allergic eye symptoms; preventive mast cell stabiliser. Nasal decongestants — short-term (maximum 7 days) for congestion. Avoid rebound congestion (rhinitis medicamentosa) from overuse.

Anaphylaxis: Recognising and Responding

Anaphylaxis is a severe, life-threatening allergic reaction. Symptoms develop rapidly: urticaria (hives), angioedema (swelling of lips/tongue/throat), breathing difficulty, stridor, fall in blood pressure, loss of consciousness. Treatment: adrenaline auto-injector (EpiPen, Emerade, Jext) immediately, followed by 999. Anyone who has had a severe allergic reaction should carry two adrenaline auto-injectors at all times and have an emergency action plan.

Browse our Allergy & Hayfever range including antihistamines, allergy nasal sprays and allergy eye drops at Huncoat Pharmacy. Related: Nasal Decongestants Guide.

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