Medicines for Allergies

What it is

An allergy is a reaction of the immune system to a substance (an allergen) that is usually harmless to most people. Instead of ignoring the substance, the immune system reacts to it, producing the symptoms of an allergic reaction. Allergies are very common, particularly in children (though they can develop at any age), and some people have several allergies or related allergic conditions. Common allergens include: pollen (causing hay fever); house dust mites; animal dander (from pets); mould; certain foods (such as nuts, milk, eggs, shellfish, and others); insect stings; certain medicines; latex; and others. The symptoms of an allergic reaction depend on the allergen and how a person is exposed, and can include: sneezing, a runny or blocked nose, and itchy, watery eyes (as in hay fever); an itchy, red rash or hives; itching or swelling (for example of the lips, face, or around the eyes); wheezing, coughing, or breathlessness; tummy symptoms (such as feeling sick, vomiting, or diarrhoea, for example with food allergies); and itchy or watery eyes. Most allergic reactions are mild to moderate and, while they can be troublesome, are not dangerous. However, some people can have a severe, life-threatening allergic reaction called anaphylaxis — a medical emergency with symptoms such as difficulty breathing, swelling of the throat or tongue, feeling faint, and collapse — which needs immediate treatment with adrenaline. Allergies are usually managed by identifying and avoiding the trigger where possible, and treating the symptoms (for example with antihistamines and other treatments); for those at risk of severe reactions, having an emergency plan and adrenaline is important, and some allergies can be assessed and, in certain cases, treated to reduce sensitivity (immunotherapy). The key messages are that allergies are common reactions of the immune system to usually harmless substances, that most are mild and managed by avoidance and treatment, and that severe reactions (anaphylaxis) are a medical emergency needing immediate adrenaline and emergency help.

How it is treated

Allergies are managed by identifying and avoiding the trigger where possible, treating the symptoms, and, for those at risk of severe reactions, having an emergency plan — with assessment and, in some cases, specific treatments available. A key step is identifying the allergen(s) responsible, which is often possible from the pattern of symptoms and their relation to exposures; where the trigger is unclear or the reaction is significant, allergy testing (such as skin prick tests or blood tests, arranged through a doctor or allergy service) can help identify it. Once the trigger is known, avoiding or reducing exposure to it is central — for example, measures to reduce house dust mites or pet exposure, avoiding specific foods (with careful label reading and awareness for food allergies), or reducing pollen exposure for hay fever. Treating the symptoms is often effective: antihistamines help with many allergy symptoms (such as itching, hives, and hay fever); other treatments are used depending on the type of allergy — for example, steroid nasal sprays and eye drops for hay fever, treatments for allergic skin reactions, and inhalers for allergic asthma; a pharmacist or doctor can advise on suitable treatments. For people at risk of severe allergic reactions (anaphylaxis) — for example with certain food, insect sting, or other severe allergies — it is important to have an emergency plan, to carry adrenaline auto-injectors and know how and when to use them, to avoid the trigger carefully, and for those around them to be aware; this is potentially life-saving. Some people are referred to an allergy specialist for assessment and management, particularly for significant, unclear, or severe allergies, and for certain allergies, treatments to reduce the body’s sensitivity over time (immunotherapy/desensitisation) may be an option in appropriate cases. Education about avoiding triggers, recognising reactions, and knowing what to do — including recognising and treating anaphylaxis as an emergency — is important. The reassuring messages are that most allergies are mild to moderate and can be well managed by avoiding triggers and treating symptoms, that help and assessment are available, and that, for those at risk of severe reactions, an emergency plan and adrenaline provide protection — while a severe allergic reaction (anaphylaxis) is a medical emergency needing immediate adrenaline and emergency help.