What should you know about OTC antihistamines?

Allergic reactions release histamine, a chemical that can cause sneezing, a runny or blocked nose, itchy eyes, an itchy throat, hives, and itching. Antihistamines block some histamine effects, so they can be useful for symptoms linked with allergic rhinitis, allergic conjunctivitis, or exposure to pets and house dust mites. They do not remove the trigger, treat every cause of a blocked nose, or replace urgent care for a severe reaction.

Read the active ingredient, dose directions, age limits, and warnings before taking a product. Some antihistamines can cause sleepiness, slower reactions, dry mouth, or blurred vision; avoid driving or alcohol until you know how you respond. Do not combine products that contain the same antihistamine. Ask a pharmacist before use if you are pregnant, breastfeeding, treating a child, or living with glaucoma, prostate problems, kidney disease, or liver disease. Nasal or eye symptoms may respond better to a product designed for that area.

Seek emergency help for swelling of the lips, tongue, or throat, trouble breathing, faintness, or rapidly worsening symptoms. Arrange medical advice when a rash is widespread, symptoms keep returning, fever or facial pain accompanies nasal symptoms, or treatment is not helping. A pharmacist can check interactions and suggest an appropriate option for milder symptoms.

Which ingredient fits my symptoms and other medicines? Could this product make me drowsy? Should I use an allergy treatment for my nose or eyes instead? What signs mean I should stop self-treatment?