Almotriptan is a triptan drug for the treatment of migraine headaches. Almotriptan is in a class of medications called selective serotonin receptor agonists. It works by narrowing blood vessels in the brain, stopping pain signals from being sent to the brain, and stopping the release of certain natural substances that cause pain, nausea, and other symptoms of migraine. Almotriptan does not prevent migraine attacks.   From: DrugBank