--- title: "Antihistamines: Uses & Side Effects | HealthAnswers" description: "Antihistamines are medicines that relieve allergy symptoms such as sneezing and itching by blocking histamine, with drowsy and non-drowsy types available." url: https://healthanswers.co.uk/treatments/antihistamines/ robots: noindex --- # Antihistamines: Uses & Side Effects | HealthAnswers Treatments Antihistamines are medicines that relieve allergy symptoms such as sneezing and itching by blocking histamine, with drowsy and non-drowsy types available. Written by HealthAnswers editorial team Medically reviewed by [HealthAnswers UK doctor review panel](https://healthanswers.co.uk/our-doctors/) Reviewed 3 July 2026 ## Quick answer What are antihistamines used for? Antihistamines are medicines that ease allergy symptoms such as sneezing, itching, a runny nose and hives. They work by blocking histamine, a chemical the body releases during an allergic reaction. Some cause drowsiness and some don't, and most are available from pharmacies. ## Who is this page for? This page is for people in the UK who want a plain-English overview of Antihistamines, including when to seek help and what NHS care usually involves. It explains general information, not what is wrong with you personally. ## Who should skip this page? Skip this page if you need a diagnosis, a prescription, or emergency care. It cannot replace a GP, pharmacist, NHS 111 or 999. If you are in immediate danger, call 999; for urgent advice that is not life-threatening, call 111 in England, Scotland or Wales, or use your GP out-of-hours service in Northern Ireland. On this page 5 sections ## Key facts about antihistamines - Antihistamines relieve allergy symptoms like sneezing, itching and hives. - They work by blocking the effects of histamine. - Some types cause drowsiness; many newer ones do not. - They are also used to help with allergic skin reactions and insect bites. ## What are antihistamines? Antihistamines are medicines that relieve the symptoms of allergies. When you have an allergic reaction, your body releases a chemical called histamine, which causes symptoms like sneezing, itching and a runny nose. Antihistamines work by blocking histamine, calming these symptoms down. ## What antihistamines are used for Antihistamines are commonly used for: - hay fever and other allergies - hives (urticaria) and itchy skin - reactions to insect bites and stings - allergic conjunctivitis (itchy, watery eyes) ## Drowsy and non-drowsy types There are two broad groups. Older antihistamines can make you feel sleepy, which is why some are also used to help with sleep. Newer ones are usually “non-drowsy” and are generally preferred for daytime use, such as managing hay fever while at work. A pharmacist can help you choose. ## Using them safely Antihistamines are available in tablets, liquids, nasal sprays and eye drops. To use them well: - follow the instructions on the packet or your prescription - if using a drowsy type, do not drive or operate machinery until you know how it affects you - tell a pharmacist about other medicines you take, as some can interact Always read the patient information leaflet. ## What antihistamines cannot treat Antihistamines help with everyday allergy symptoms, but they are **not** a treatment for a severe allergic reaction (anaphylaxis). If someone has swelling of the face, lips or throat, difficulty breathing, or feels faint, this is an emergency — call 999 immediately. ## ! Important safety information for antihistamines A pharmacist can recommend the right antihistamine for you. Tell them about any other medicines you take and any health conditions. Avoid driving or operating machinery if you take a type that makes you drowsy until you know how it affects you. Antihistamines are **not** a treatment for a serious allergic reaction (anaphylaxis) — for swelling of the face or throat, difficulty breathing or feeling faint, call **999**. ## Common questions about antihistamines What are antihistamines used for? They are mainly used for allergies — hay fever, allergic reactions, hives and itchy skin, and reactions to insect bites and stings. Some are also used for travel sickness or to help with sleep, though that is a separate use. What is the difference between drowsy and non-drowsy antihistamines? Older "first-generation" antihistamines can make you sleepy, while newer "second-generation" ones usually do not. For daytime allergy relief, a non-drowsy type is often preferred. A pharmacist can advise which suits your needs. Can I take antihistamines every day? Many people take a non-drowsy antihistamine daily during allergy season, and this is generally fine. If you find you need them long term or they are not controlling your symptoms, speak to a pharmacist or GP. Do antihistamines treat a severe allergic reaction? No. Antihistamines help mild to moderate allergy symptoms but are not a treatment for anaphylaxis — a severe, life-threatening reaction. That needs emergency treatment (adrenaline) and a 999 call. ## Sources - [NHS — Antihistamines](https://www.nhs.uk/conditions/antihistamines/)