Bimatoprost (Lumigan, Durysta, and others)

How Medicare covers it

Part D (eye drops and gel used at home). Part A during a covered inpatient stay. The clinician-placed implant form also has a Part B basis (see Part B status).

What it treats

High pressure inside the eye (elevated intraocular pressure) in people with open-angle glaucoma or ocular hypertension. Lowering eye pressure helps reduce the risk of optic nerve damage and vision field loss that glaucoma can cause.

What it is for, in depth

Lumigan (bimatoprost ophthalmic solution 0.01%) is a once-a-day prescription eye drop for adults whose pressure inside the eye is too high. The label names two conditions: open-angle glaucoma, the common form of glaucoma in which fluid drains too slowly and pressure slowly damages the optic nerve, and ocular hypertension, where eye pressure is high but glaucoma damage has not yet occurred. High eye pressure is a major risk factor for glaucomatous vision loss — the higher the pressure, the greater the chance of optic nerve damage — so the drop is used every evening over the long term to keep pressure down, not just when the eye feels uncomfortable; most people feel no symptoms from high pressure at all. It is often a first prostaglandin drop tried for these conditions and can be combined with other pressure-lowering eye drops given at least 5 minutes apart. It comes in one strength, 0.01%, in 2.5 mL, 5 mL, and 7.5 mL bottles, and only 1 drop once each evening should be used.

How it works

Bimatoprost (Lumigan) is a prostaglandin analog — a man-made version of natural substances called prostamides. It lowers pressure inside the eye by increasing the outflow of aqueous humor, the fluid inside the eye, through both the trabecular meshwork and the uveoscleral drainage routes. When more fluid drains out, pressure falls. In a 12-month study, once-daily Lumigan 0.01% lowered eye pressure by up to 7.5 mmHg from an average starting pressure of 23.5 mmHg.

How it is taken

Eye drops (Lumigan, bimatoprost ophthalmic solution 0.01%, 0.1 mg/mL) put in the affected eye or eyes once a day in the evening — 1 drop only. Do not use it more than once a day: using prostaglandin analogs more often can actually make the pressure-lowering effect weaker. Pressure starts to fall about 4 hours after the first dose, with the greatest effect in about 8 to 12 hours. It can be used with other eye drops to lower pressure, but different drops should be given at least 5 minutes apart. Take soft contact lenses out before putting the drops in and wait 15 minutes before putting them back in, because the preservative benzalkonium chloride can be absorbed by the lenses. Supplied in 2.5 mL, 5 mL, and 7.5 mL dispenser bottles.

Common side effects

The most common side effect in the 12-month study was conjunctival hyperemia — redness of the clear covering of the eye — in 31% of patients, and about 1.6% stopped treatment because of it. Other reactions in 1% to 4% of patients included swelling or bleeding of the conjunctiva, eye irritation, eye pain, itchy eyes, red or itchy eyelids, growth of eyelashes, punctate keratitis, skin darkening, blurred vision, and reduced visual sharpness. Post-marketing reports include dry eye, eye discharge, tearing, headache, dizziness, light sensitivity, and allergy-type eye and skin reactions.

Serious warnings

Bimatoprost gradually darkens pigmented tissues: the iris (colored part of the eye) can become more brown, and this iris change is likely to be permanent; eyelid skin darkening and eyelash darkening can also occur and eyelid darkening may be reversible after stopping. The color change comes from more melanin, develops slowly over months to years, and patients who develop noticeably increased iris pigmentation can keep using it but should be examined regularly. The drops can cause or worsen inflammation inside the eye, and swelling of the macula (macular edema, including cystoid macular edema) has been reported. Bacterial keratitis (a serious cornea infection) has been linked to contaminated multi-dose drop bottles, so the tip must not touch the eye or any surface. Deepening of the eyelid fold and other eyelid changes from loss of fat around the eye have also been reported after approval.

Who should be careful

Do not use Lumigan if you are allergic (hypersensitive) to bimatoprost or any ingredient in the drops. Use caution if you have active inflammation inside the eye (such as uveitis), because prostaglandin analogs can make inflammation worse; if you have no natural lens (aphakia), a replacement lens with a torn back capsule, or other risk factors for macular edema (swelling at the back of the eye); and if you have a corneal disease or a break in the surface of the eye, which raises the risk from a contaminated bottle. People treated in only one eye should know the treated eye can gradually look different — browner iris, darker eyelid skin, and longer, darker lashes — than the untreated eye.

Major interactions

The Lumigan label does not list systemic drug-drug interactions; the important use interactions are with other eye products. Lumigan may be used together with other topical eye drugs to lower eye pressure, but if more than one eye drug is used, they should be given at least 5 minutes apart so one does not wash out the other. Using Lumigan more than once a day — or adding extra prostaglandin analog doses — can lessen its pressure-lowering effect, so the once-daily evening schedule should be followed exactly. The preservative benzalkonium chloride in the drops can be absorbed by soft contact lenses and discolor them, so lenses should be removed before use and put back in 15 minutes later. Tell your eye doctor about every eye drop and eye condition you have, including inflammation inside the eye, so combined use can be planned safely.

Cost and saving notes

If this drug is covered under your Medicare Part D plan and the cost is high, you can ask your plan for a tier exception to pay a lower cost share. If you have limited income, Extra Help (the Part D Low-Income Subsidy) can lower your Part D premiums and drug costs. In 2027, your total yearly out-of-pocket spending on covered Part D drugs is capped at $2,400, and you can spread those costs out in monthly payments through the Medicare Prescription Payment Plan. Ask your pharmacist and plan what you would pay before you fill, and check whether a generic or a different drug in the same class is on a lower tier. Ask your plan and pharmacist whether generic bimatoprost 0.01% or another prostaglandin eye drop on a lower tier would cost less than brand Lumigan for this once-a-day treatment.

Why it is in its tier

Bimatoprost (Lumigan, Durysta, and others) sits on Tier 3 in 82.98% of the plans that list it (4284 of 5163 listing plans). Tier 3 is the preferred brand tier — mid-level copays or coinsurance. The data-visible drivers: It is sold both as a brand product and in generic form, and the CMS dashboard puts its average Part D spending at about $1,921 per beneficiary for 2024 — a mid-cost drug, which matches where plans place it. It is listed by 93.96% of Part D plans. The tier shown is the most common one; individual plans vary.

Sources

• LUMIGAN (BIMATOPROST) SOLUTION/ DROPS [ALLERGAN, INC.] — DailyMed
• MedlinePlus — National Library of Medicine
• MedlinePlus — Bimatoprost Ophthalmic

What official patient guides say

Bimatoprost ophthalmic comes as a solution (liquid) to put in the eye, usually once a day in the evening in the affected eye or eyes, at around the same time every day. Use it exactly as directed, and keep using it even if you feel well, because it controls glaucoma and ocular hypertension but does not cure them; do not stop without talking to your doctor. To put in the drops, wash your hands, tilt your head back and pull down the lower lid to form a pocket, place one drop in without touching the dropper tip to your eye or anything else, close your eye for 2 to 3 minutes, and press gently on the tear duct. Wait at least 5 minutes before another drop or eye medication. If you wear soft contact lenses, remove them before use and put them back in 15 minutes later. If you miss a dose, put it in as soon as you remember, unless it is almost time for the next dose; then skip it and do not use a double dose. Store it tightly closed at room temperature, away from excess heat and moisture, and out of reach of children.

Source: MedlinePlus — Bimatoprost Ophthalmic

Part D formulary coverage

Source: CMS Prescription Drug Plan Formulary, Pharmacy Network, and Pricing Information Files — Monthly file 2026-10-15 (plan year 2027), file 2027_20261008.zip (data.cms.gov dataset ed1496ea-23e7-41f1-9292-172fa842ccfb): basic drugs formulary file + plan information file, both dated 20261031 inside the zip; downloaded and aggregated 2026-10-30. Medication RxCUI sets resolved through the NLM RxNav (RxNorm) API.

What you pay

Without insurance, the cash benchmark is 43.46054 per unit (BIMATOPROST 0.01% EYE DROPS) — about nan for 30 units. NADAC benchmark — the average price pharmacies pay (CMS, as of 2026-11-04). Pharmacy shelf prices vary.

A tier is not a price; what you pay depends on your plan, pharmacy, and benefit stage; Extra Help or Medicaid can lower it further.

Sources: CMS Plan Benefit Package + formulary data; CMS NADAC · Checked 2026-11-07

Coverage by plan and tier

Of the 5,495 Medicare drug plans we track for 2027, 5,163 list Bimatoprost (Lumigan, Durysta, and others) — 94.0% of plans. Most of those plans put it on Tier 3: 4,284 plans, 83.0% of the plans that list it. Other plans place it on Tier 2 (623 plans), Tier 1 (131 plans) or Tier 4 (125 plans). For example: Aetna Medicare Dual Extra (HMO D-SNP) puts it on Tier 3; Aetna Medicare Dual Extra Care (PPO D-SNP) puts it on Tier 3; Aetna Medicare Value Plus (PPO) puts it on Tier 3. You can compare these plans side by side on our Medicare Advantage hub. A tier is not a price. What you pay also depends on whether you have met your plan';s deductible, whether the drug costs a flat copay or a share of the price, and whether you get Extra Help or Medicaid.

Read next

• Part D in 2027: The $700 Deductible, the $2,400 Cap, and the $35 Insulin Rule
• Extra Help in 2027: Lower Drug Copays and Who Qualifies
• Checking Medicare Savings Programs and Extra Help

Part D spending averages (2024)

Source: CMS Medicare Part D Spending by Drug (Drug Spending Dashboard), release RY26 P04 V10, data through 2024 (DSD_PTD_RY26_P04_V10_DY24_BGM.csv), downloaded 2026-10-30

Companies covering this drug

Part D and Medicare Advantage plan sponsors that list this drug on a formulary, 50 at a time.