The Latisse prescribing information (bimatoprost 0.03%, for eyelashes) says: "Increased iris pigmentation has occurred when bimatoprost solution was administered. Patients should be advised about the potential for increased brown iris pigmentation which is likely to be permanent". The same label reports darkening of periorbital pigmented tissues and eyelashes. Studies in other groups of people report different things, and this guide keeps them apart.
What the Latisse label says about the iris
The label explains that the pigmentation change is due to increased melanin content in the melanocytes rather than to an increase in the number of melanocytes. It states that the long term effects of increased pigmentation are not known. It also says iris color changes "may not be noticeable for several months to years".
The label's adverse reaction information comes from a multicenter, double-masked, randomized, vehicle-controlled, parallel study of 278 adult patients for 4 months of treatment. The same section lists iris hyperpigmentation, with foreign body sensation and hair growth abnormal, as additional adverse reactions seen in clinical trials experience. The quoted sentence gives no rate for it.
What the Latisse label says about eyelid and nearby skin
The label states: "Bimatoprost has been reported to cause pigment changes (darkening) to periorbital pigmented tissues and eyelashes. The pigmentation is expected to increase as long as bimatoprost is administered, but has been reported to be reversible upon discontinuation of bimatoprost in most patients".
The label also lists skin hyperpigmentation among its most frequently reported trial reactions, then states: "These reactions occurred in less than 4% of patients". That sentence covers 6 listed reactions. It is not an iris rate.
Studies, by group studied
| Question | What the source says |
|---|---|
| 2014 chart review of bimatoprost 0.03% for eyelash hypotrichosis (observational): iris findings? | "No instances of iris hyperpigmentation occurred" in this retrospective review. Its author affiliations include Allergan, Inc. and SCI Scientific Communications and Information. |
| 2017 chart review of cutaneous bimatoprost, concentration not stated (observational): iris findings? | The abstract says no iris pigmentation change was noted. |
| 2012 prospective study of 52 Japanese patients with glaucoma or ocular hypertension treated with bimatoprost, concentration not stated: what increased? | Increases were evident after treatment in eyelash bristle (53.8%), iris pigmentation (50.0%), eyelash growth (46.2%), vellus hair of the lid (40.4%), and eyelid pigmentation (7.7%). |
| 2007 review of prostaglandin F2alpha analogues used for elevated intraocular pressure: what is reversible? | The review states that conjunctiva hyperaemia, eyelash changes and cystoid macular oedema are reversible, but certain other side effects, such as increased iris pigmentation, are not. |
| 2021 literature review of bimatoprost for eyelash growth: how well is iris pigmentation studied? | The review says the risk of increased iris pigmentation remains inadequately investigated. |
Why the numbers are not combined
The 52-patient study is in people using bimatoprost for glaucoma or ocular hypertension, and its abstract does not give the concentration. The 2014 chart review covers the 0.03% product for eyelash hypotrichosis. The 2017 chart review covers cutaneous application at an unstated concentration. The 2007 review covers topically applied analogues used for elevated eye pressure. A percentage from a single group does not transfer to another, and the label's quoted text gives no iris rate for eyelash use.
What this does not tell you
The 2 chart reviews and the 52-patient study are observational, so they cannot show cause and effect. The summaries used here do not say how long patients in the chart reviews used bimatoprost, and the label says iris color changes may not be noticeable for several months to years. The wording "likely to be permanent" belongs to the Latisse label. The 2007 review makes its own statement about a different group of drugs.
The label describes the approved Latisse product. The FDA states that "Compounded drugs are not FDA approved, which means the agency does not review their safety, effectiveness or quality before they are marketed." Nothing here shows that a compounded product matches an approved one. A licensed provider decides whether treatment suits a person.