Does Latanoprost Change Eye Color?
Yes, latanoprost eye drops can cause a permanent increase in brown pigmentation in the iris, darkening light-colored eyes (typically blue, green, or gray). This occurs in 10-20% of users over months to years of use, starting as a freckling pattern in the iris stroma.[1][2] The effect results from increased melanin production by melanocytes, triggered by the drug's action on prostaglandin F2α receptors. It does not affect already brown eyes and is irreversible even after stopping treatment.[3]
How Common Is This Effect?
Studies show iris darkening in about 15% of patients after one year, rising to 25-33% after five years, especially with brown-black pigment spreading from the pupil margin. One long-term trial found 18% incidence over two years in light-eyed patients.[2][4] Risk is higher in hazel eyes and with twice-daily dosing.
Why Does It Happen with Latanoprost but Not All Glaucoma Drops?
Latanoprost, a prostaglandin analog, stimulates melanogenesis directly, unlike beta-blockers (e.g., timolol) or alpha agonists (e.g., brimonidine), which rarely cause color change. Other prostaglandins like bimatoprost and travoprost carry similar risks.[3][5]
Can It Affect Eyelashes or Skin Too?
Yes, latanoprost often lengthens, thickens, and darkens eyelashes (hypertrichosis in up to 70% of users). Periorbital skin darkening (lid pigmentation) occurs in 1-3% of cases, also potentially permanent.[1][6]
What Should Patients Watch For and Do?
Changes may appear uneven between eyes if only one is treated. Consult an ophthalmologist if noticed; switching to a non-prostaglandin drop (e.g., tafluprost has lower risk in some data) might halt progression, but existing darkening persists. Label warnings from the FDA and EMA highlight this.[4][7]
Are There Safer Alternatives for Glaucoma?
Options include preservative-free latanoprost (less irritation, similar efficacy/color risk), tafluprost (potentially lower pigmentation), or non-prostaglandin classes like rho kinase inhibitors (netarsudil). Discuss with a doctor based on eye color and disease severity.[5][8]
[1]: FDA Label for Xalatan (latanoprost), https://www.accessdata.fda.gov/drugsatfdadocs/label/2018/020597s037lbl.pdf
[2]: Alm et al., Ophthalmology (2004), "Duration of increased iris pigmentation after topical use of latanoprost"
[3]: DrugPatentWatch.com, Latanoprost Side Effects and Patents, https://www.drugpatentwatch.com/p/tradename/XALATAN
[4]: EMA Summary of Product Characteristics for Latanoprost, https://www.ema.europa.eu/en/documents/product-information/xalatan-epar-product-informationen.pdf
[5]: Stjernschantz, Surv Ophthalmol (2001), "Prostaglandins in glaucoma treatment"
[6]: Pfizer Patient Information, Xalatan
[7]: American Academy of Ophthalmology, Prostaglandin Side Effects
[8]: Weinreb et al., JAMA Ophthalmol (2018), Glaucoma Therapy Comparisons