Latanoprost Drug Interactions: What to Avoid and What to Tell Your Doctor

Latanoprost is generally safe and has fewer systemic interactions than many medications — because it's applied directly to the eye, very little enters the bloodstream. However, it does have several clinically important interactions, particularly with other ophthalmic medications. Here's what every latanoprost patient should know.

Most Important Interaction: Other Prostaglandin Eye Drops

The most clinically significant interaction with latanoprost is using it alongside another prostaglandin analogue.

Avoid combining: Bimatoprost (Lumigan), travoprost (Travatan Z), tafluprost (Zioptan), latanoprostene bunod (Vyzulta)

Why: Using two or more prostaglandin analogues simultaneously — or using latanoprost more than once daily — can paradoxically increase intraocular pressure (IOP) rather than lower it further. This counterintuitive effect is well established and is the reason patients should never self-add a second prostaglandin.

What to do: If your IOP is not adequately controlled on latanoprost alone, your doctor will add a drug from a different class (beta-blocker, carbonic anhydrase inhibitor, alpha agonist) rather than a second prostaglandin.

NSAIDs (Non-Steroidal Anti-Inflammatory Drugs)

Both systemic NSAIDs (aspirin, ibuprofen, naproxen, celecoxib) and topical ophthalmic NSAIDs (bromfenac, diclofenac ophthalmic, ketorolac ophthalmic) can interact with latanoprost.

The interaction: Conflicting data exists — some studies show NSAIDs may reduce latanoprost's IOP-lowering effect, while others show the opposite. The clinical impact in most patients is modest.

What to do: Tell your eye doctor if you take regular NSAIDs (including low-dose aspirin). Your IOP may need monitoring if you're on chronic NSAID therapy. For ophthalmic NSAIDs, use them at least 5 minutes apart from latanoprost.

Thimerosal-Containing Eye Drops

If you use any eye drops containing thimerosal (a mercury-based preservative sometimes found in older ophthalmic products), do not mix them with latanoprost in the same eye at the same time.

The interaction: Thimerosal and latanoprost can precipitate (form a visible deposit) when they contact each other in the eye. This precipitation may reduce efficacy and could potentially irritate the eye.

What to do: Always wait at least 5 minutes between any two ophthalmic medications. If you use thimerosal-containing drops, space them at least 5 minutes from your latanoprost dose.

Contact Lens Preservative Interaction

Latanoprost contains benzalkonium chloride (BAK) as a preservative. BAK can be absorbed by soft contact lenses, potentially discoloring them or causing ocular surface irritation.

What to do: Remove soft contact lenses before applying latanoprost. Wait at least 15 minutes after instilling the drop before reinserting your contacts.

Interactions to Watch When Adding Other Glaucoma Drugs

Latanoprost is often used in combination with other glaucoma medications when monotherapy is insufficient. Safe combinations include:

Timolol (beta-blocker): Safe and commonly combined. Fixed-dose combinations (latanoprost/timolol) are available. Wait 5 minutes between separate drops.

Brimonidine (alpha agonist): Safe combination; additive IOP reduction. Wait 5 minutes between drops.

Dorzolamide/brinzolamide (carbonic anhydrase inhibitors): Safe combination; additive IOP reduction. Wait 5 minutes between drops.

What to Tell Your Doctor

Before starting latanoprost, tell your prescriber about: all other eye drops (prescription and OTC), any history of herpes simplex eye disease, active eye inflammation or uveitis, pregnancy or breastfeeding, severe asthma (for the preservative benzalkonium chloride), and any other prescription or over-the-counter medications. See also: latanoprost side effects | what is latanoprost?