what is antihistamines

Antihistamines are a class of drugs that are commonly used to treat symptoms of allergies caused by too much histamine, a chemical created by the bodys immune system. Histamines cause allergy symptoms such as coughing, sneezing, itching, blocked noses, and watery eyes. Antihistamines work by blocking some of the adverse effects caused by histamines in response to an allergen entering the body. They are most commonly used by people who have allergic reactions to pollen and other allergens, but they are also used to treat a variety of other conditions such as stomach problems, colds, anxiety, motion sickness, nausea, vomiting, and insomnia. Antihistamines are divided into two major subtypes: H-1 receptor antagonists or H-1 blockers, which are used to treat allergy symptoms, and H-2 receptor antagonists or H-2 blockers, which are used to treat gastrointestinal conditions. Antihistamines come in many forms, including tablets, capsules, liquids, nasal sprays, eye drops, creams, lotions, and gels. Some antihistamines cause less sleepiness than others, and non-drowsy antihistamines are generally the best option, as they are less likely to make you feel sleepy. However, types that make you feel sleepy may be better if your symptoms stop you from sleeping. It is important to read the label carefully and ask a pharmacist for advice if you are unsure which medicine to try, as not all antihistamines are suitable for everyone.