Gardenal Syrup is used in the treatment of epilepsy and the symptoms associated with it like seizures. It contains Phenobarbital, which works by controlling the abnormal electrical activity in the brain thereby prevents and control seizures. Additionally, it calms down the excited chemical of the brain and makes a person relaxed, so that the brain can function properly. In some cases, it may cause side effects such as drowsiness, lethargy, residual sedation, vomiting, and headache. Before taking this medicine, you should tell your doctor if you are allergic to any of its components or if you are pregnant/breastfeeding, and about all the medications you are taking and pre-existing medical conditions.