Reswas Syrup is a combination medicine which belongs to the class of expectorants. It is used in the treatment of dry cough. This medicine works by blocking the action of histamine and transmission of nerve signals from the cough centre in the brain to the muscles that produce cough thus reduce cough associated with cold/flu, allergies, and throat irritation. You may experience common side effects like headache, dizziness, numbness, drowsiness, or nausea.