Alverine is a drug used for functional gastrointestinal disorders. Alverine is a smooth muscle relaxant. Smooth muscle is a type of muscle that is not under voluntary control; it is the muscle present in places such as the gut and uterus. Alverine acts directly on the muscle in the gut, causing it to relax. This prevents the muscle spasms which occur in the gut in conditions such as irritable bowel syndrome and diverticular disease. Diverticular disease is a condition in which small pouches form in the gut lining. These pouches can trap particles of food and become inflamed and painful. In irritable bowel syndrome the normal activity of the gut muscle is lost. The muscle spasms result in symptoms such as heartburn, abdominal pain and bloating, constipation or diarrhoea. By relaxing the gut muscle, alverine citrate relieves the symptoms of this condition. Alverine also relaxes the smooth muscle in the womb (uterus). It is therefore also used to treat painful menstruation, which is caused by muscle spasms in the uterus (dysmenorrhea).