Dichloralphenazone is a 1:2 mixture of antipyrine with chloral hydrate. In combination with paracetamol and isometheptene, it is the active ingredient of medications for migraine and vascular (tension) headaches, including Epidrin and Midrin. Performance impairments are common with this drug and caution is advised, for example when driving motor vehicles. This drug acts on the blood vessels in the brain and causes them to constrict, thus relieving the pain of a headache or migrain. Additional uses of Dichloralphenazone include sedation for the treatment of short-term insomnia, although there are probably better drug choices for the treatment of insomnia.^[1]