Brand name for the prescription drug whose active ingredient is the prostaglandin analogue bimatoprost. Latisse is sold by Allergan (of Botox fame), and is the only FDA-approved treatment for enhancing eyelash growth, including lash length, thickness, and darkness. Latisse contains 0.03% of bimatoprost, whose actual chemical name is (Z)-7-[(1R,2R,3R,5S)-3,5-Dihydroxy-2-[(1E,3S)-3-hydroxy-5-phenyl-1-pentenyl]cyclopentyl]-5-N-ethylheptenamide. This nearly indecipherable ingredient is used in eye drop form for treating glaucoma or ocular hypertension under the brand name Lumigan, also owned by Allergan. Ophthalmologists treating patients with Lumigan happened to notice that when their patients started using this medication as eye drops that their glaucoma got better and their eyelashes grew longer, darker, and fuller—an unexpected side effect that made many glaucoma-stricken women with sparse lashes very happy! Latisse is a prescription-only medication for good reason!
There are minor side effects such as itching, inflammation, a burning sensation, and redness that can be persistent, but these will stop if you discontinue use. A far more serious but rarely-occurring side effect with Latisse is that it can increase blood flow to the eye making capillaries look far more pronounced. It can also darken the eyelid or skin under the eye, which can be reversible but in rare cases it can stick around indefinitely. Although not reflected in clinical studies, it's been reported that Latisse use may also cause increased brown pigmentation of the colored part of the eye, which is likely to be permanent. All of these risks are heightened if a consumer purchases Latisse (or what they think is Latisse) online without a prescription (Sources: Journal of Cosmetic Dermatology, June 2010, pages 96–102; Clinical Ophthalmology, April 2010, pages 349–358; Dermatologic Surgery, Epublication, April 2010; and www.fda.gov).