Eletriptan HBr is primarily used in the treatment of acute migraine headaches. It works by narrowing the blood vessels around the brain and reducing substances in the body that can trigger headache pain, nausea, and sensitivity to light and sound. It is most effective when taken at the first sign of a migraine, helping to alleviate symptoms quickly and restore normal function. However, it is not intended for the prevention of migraines or for use in cluster headaches. Patients are advised to follow their healthcare provider's instructions carefully to avoid overuse, which can lead to medication-overuse headaches.