What should you know about COVID and antihistamines?

Antihistamines reduce the effects of histamine, a chemical involved in allergic reactions. They may help with a runny or blocked nose, itchy eyes or an itchy throat caused by conditions such as allergic rhinitis, allergic conjunctivitis, pet allergy or house dust mite allergy.

COVID-19 is an infection, not an allergy. Fever, cough, marked fatigue, a generally unwell feeling or a change in breathing points to a different pattern and should not be explained away as allergy. Some people have both an allergy and an infection, so one medicine may relieve one symptom without treating the underlying illness.

Use the product exactly as directed and check whether it causes drowsiness, especially before driving or operating equipment. Tell a pharmacist or clinician about pregnancy, glaucoma, prostate symptoms, heart rhythm problems, kidney or liver disease, and other medicines. Avoid doubling up combination cold products that contain the same ingredient.

If you develop fever, worsening cough, unusual weakness or breathing changes, consider COVID-19 testing and seek advice based on your symptoms and risk factors. Keep fluids nearby and rest while monitoring the trend rather than masking deterioration with repeated doses.

Get urgent help for difficulty breathing, swelling of the lips or throat, fainting, severe wheezing, chest pain, blue or grey lips or new confusion. Contact a clinician if symptoms persist despite allergy treatment, fever appears, or you are unsure whether symptoms are allergic or infectious. A severe allergic reaction needs emergency care.

Ask whether your symptoms fit an allergy, COVID-19 or another condition, and which antihistamine is suitable with your medicines. Check how long to use it, whether drowsiness is expected, and which changes require a review.