Cetirizine is an antihistamine medicine that relieves the symptoms of allergies. It's used to treat: hay fever conjunctivitis (red, itchy eye) eczema hives (urticaria) reactions to insect bites and stings some food allergies Cetirizine is known as a non-drowsy antihistamine. It's much less likely to make you feel sleepy than some other antihistamines. Always read the instruction leaflet. Image used is for illustration purposes only. Packaging may vary.