Understanding anti-allergy medicines

Antihistamine tablets, liquids, nasal sprays, and eye drops act in different places and may have different side effects. Matching the formulation to the main problem can limit unnecessary medicine exposure.

Antihistamines block the effects of histamine, a chemical involved in allergic itching, sneezing, and watery discharge. They can help allergic rhinitis and allergic conjunctivitis, but nasal congestion may respond differently from itching or a runny nose.

Some antihistamines are more likely to cause sleepiness, slowed reactions, dry mouth, or blurred vision. A product labelled non-drowsy can still affect some people. Alcohol and other sedating medicines may add to impaired alertness.

Read the active ingredient, dose, age limits, and warnings rather than choosing by brand name alone. Check with a pharmacist if you are pregnant or breastfeeding, giving medicine to a child, older, or living with kidney, liver, heart, eye, or urinary problems.

Avoid combining allergy, cold, cough, and sleep products until their ingredients have been compared. Use eye drops only in the eyes and nasal products only in the nose. Reducing exposure to a known trigger may also decrease symptoms and medicine use.

Get emergency help for breathing difficulty, throat or tongue swelling, collapse, confusion, or rapidly spreading symptoms after a suspected exposure. Oral antihistamines do not replace adrenaline when a person has a prescribed emergency plan for anaphylaxis.

Request clinical advice when symptoms remain uncontrolled, the diagnosis is uncertain, side effects interfere with daily activities, or episodes repeatedly involve food, medicines, insect stings, wheezing, or extensive skin swelling.

Bring a list of prescription, non-prescription, and herbal products. Ask which symptom the medicine targets, whether a local spray or drop is preferable, how sedation could affect work or driving, and when treatment should be reviewed.