View Uses, Benefits, and Price of Alerid Syrup at Apollo Pharmacy. Alerid 5 MG Syrup is used to treat common allergy symptoms such as sneezing, runny nose, cough, etc. It contains cetirizine and may cause side effects such as sleepiness, diarrhoea, nausea, etc. Alerid Syrup is an antihistamine medicine used to treat allergies. It contains cetirizine, which works by blocking the effects of a chemical messenger called histamine. It may cause side effects like abdominal pain, headache, or diarrhoea. Before starting this medicine, inform your doctor if your child is taking any other medicines or has pre-existing medical conditions. View Uses, Benefits, and Price of Alerid Syrup at Apollo Pharmacy . Alerid Syrup is an antihistamine medicine used to treat allergies . It contains cetirizine, which works by blocking the effects of a chemical messenger called histamine. It may cause side effects like abdominal pain, headache, or diarrhoea.