Acetazolamide, sold under the trade name Diamox among others, is a medication used to treat glaucoma, epilepsy, altitude sickness, periodic paralysis, idiopathic intracranial hypertension (raised brain pressure of unclear cause), urine alkalinization, and heart failure. It may be used long term for the treatment of open angle glaucoma and short term for acute angle closure glaucoma until surgery can be carried out. It is taken by mouth or injection into a vein. Acetazolamide is a first generation carbonic anhydrase inhibitor and it decreases the ocular fluid and osmolality in the eye to decrease intraocular pressure.