Latanoprost: what it treats, how to use it, side effects
Last updated September 3, 2026.
Latanoprost is a prostaglandin analog - it lowers pressure inside the eye by increasing the outflow of natural eye fluids. You may know it as Xalatan. Glaucoma steals vision silently; the nightly drop is the standing defense.
What does it treat?
Glaucoma - the pressure-driven condition that gradually steals vision - and ocular hypertension, elevated eye pressure without damage yet.
How do you use it?
One drop in the affected eye or eyes, once a day, in the evening - more often is not better: prostaglandin drops can lose effect with overuse. Wash hands, tilt back, one drop, then gentle pressure at the inner corner of the eye for a minute to keep the drug on the eye. Contact lenses come out first and wait 15 minutes before going back. Other eye drops: space at least 5 minutes apart. Missed dose: skip it if the next evening is near; never double up.
Side effects to know
- Common: stinging, burning, irritated, or itchy eyes, dry eyes, a something-in-the-eye feeling, headache, and dizziness. Two cosmetic effects to expect: gradual darkening of the iris (usually permanent) and longer, thicker eyelashes on the treated eye.
- Serious - call your doctor immediately: eye sensitivity to light, changes in vision, and eye or eyelid redness.
Who should not use it?
Flag any history of eye inflammation (iritis, uveitis), macular edema, lens problems, or eye surgery - each shifts the risk picture. If an eye infection or injury develops while using it, call your doctor before the next drop. If you become pregnant, call your doctor.
When is it an emergency?
Sudden vision loss, severe eye pain with nausea, or halos around lights is same-day eye emergency care - the acute pressure-attack pattern. For accidental swallowing, call Poison Control at 1-800-222-1222. Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper.
What a Pymander AI doctor consult looks like
Illustrative example, not a real member's messages.
Common questions
Why do I take it in the evening, and only once a day?
The pharmacology: prostaglandin analogs work best dosed at night, and the label sets once daily - using it more often can actually blunt the pressure-lowering effect. One drop, every evening, is the maximum benefit. The brush-your-teeth anchor is the habit that never forgets.
Will it really change my eye color?
Yes, gradually: latanoprost can darken the iris - more brown pigment - developing over months to years, usually permanent. Hazel and mixed-color eyes notice it most. It is cosmetic, not harmful, but it is worth knowing before the mirror surprises you. Eyelash growth - longer, thicker, sometimes darker - comes with it, also on the treated eye.
Why do I press the corner of my eye after the drop?
Nasolacrimal occlusion: the tear duct drains drops into the nose and throat, where they absorb into the body - gentle finger pressure at the inner corner for a minute keeps the drug on the eye and the systemic dose low. It is one minute that makes the drop work better and travel less.
Can I keep wearing contact lenses?
Yes, with the 15-minute rule: lenses come out before the drop - the preservative absorbs into soft lenses - and wait 15 minutes before reinserting. Nightly dosing makes this easy: lenses out for the evening, drop in, bed. Any eye redness or irritation that persists gets checked before the next lens day.
What happens if I get an eye infection or injury?
Pause and call: an infected or injured eye changes the safety picture for any eye drop, so the doctor decides whether the drops continue through it. Bottle hygiene matters here too - the tip never touches the eye, fingers, or any surface. A contaminated bottle plus a healing eye is a bad combination.
What happens if I miss a dose of latanoprost?
Skip it and take the next one at the regular evening time - never double up. Once-daily drugs forgive a single miss; the pressure creeps back over weeks of misses, silently. If evenings are unreliable, move the anchor - with the evening meal or a bedside alarm - rather than accepting the drift.