Antihistamines

Antihistamines block histamine, a symptom-causing chemical released by your immune system during an allergic reaction.

Pills and liquids

Oral antihistamines are available over-the-counter and by prescription. They ease a runny nose, itchy or watery eyes, hives, swelling, and other signs or symptoms of allergies. Because some of these drugs can make you feel drowsy and tired, take them with caution when you need to drive or do other activities that require alertness.

Antihistamines that tend to cause drowsiness include:

• Diphenhydramine
• Chlorpheniramine

These antihistamines are much less likely to cause drowsiness:

• Cetirizine (Zyrtec, Zyrtec Allergy)
• Desloratadine (Clarinex)
• Fexofenadine (Allegra, Allegra Allergy)
• Levocetirizine (Xyzal, Xyzal Allergy)
• Loratadine (Alavert, Claritin)

Nasal sprays

Antihistamine nasal sprays help relieve sneezing, itchy or runny nose, sinus congestion, and postnasal drip. Side effects of antihistamine nasal sprays might include a bitter taste, drowsiness or feeling tired. Prescription antihistamine nasal sprays include:

• Azelastine (Astelin, Astepro)
• Olopatadine (Patanase)

Eyedrops

Antihistamine eyedrops, available over-the-counter or by prescription, can ease itchy, red, swollen eyes. These drops might have a combination of antihistamines and other medicines.

Side effects might include headache and dry eyes. If antihistamine drops sting or burn, try keeping them in the refrigerator or using refrigerated artificial-tear drops before you use them. Examples include:

• Ketotifen (Alaway, Zaditor)
• Olopatadine (Pataday, Patanol, Pazeo)
• Pheniramine and naphazoline (Visine, Opcon-A, others)