What Is Dorzolamide? Uses, Dosage, and What You Need to Know in 2026

If your eye doctor has prescribed dorzolamide — or you've seen it mentioned in connection with glaucoma treatment — you probably have questions. What exactly is it? What does it do? How do you use it? This guide covers all the key facts about dorzolamide in plain English.

What Is Dorzolamide?

Dorzolamide is a prescription eye drop medication used to lower pressure inside the eye. It belongs to a drug class called carbonic anhydrase inhibitors (CAIs) and works by reducing the amount of fluid your eye produces.

It was originally sold under the brand name Trusopt, developed by Merck. Trusopt was approved by the FDA in December 1994 and was actually the first drug ever developed using a technique called structure-based drug design — a milestone in pharmaceutical history. The brand-name Trusopt has since been discontinued, and dorzolamide is now available only as a generic medication.

In 2023, dorzolamide was the 190th most commonly prescribed medication in the United States, with more than 2 million prescriptions written. It is also available in a combination product with timolol (a beta-blocker) under the brand name Cosopt, with generic versions widely available.

What Is Dorzolamide Used For?

Dorzolamide is FDA-approved to treat:

• Open-angle glaucoma: The most common type of glaucoma, where the eye's drainage canal slowly becomes blocked over time, causing elevated pressure that can damage the optic nerve and lead to vision loss.
• Ocular hypertension: Elevated intraocular pressure (IOP) without (yet) any optic nerve damage or visual field loss. It's a significant risk factor for developing glaucoma.

Dorzolamide can be used as a single agent or added to other IOP-lowering eye drops (particularly prostaglandin analogs or beta-blockers) when one medication alone doesn't provide adequate pressure control.

Dorzolamide Dosage: How to Use It

The standard prescribed dose of dorzolamide is:

• Dose: One drop in the affected eye(s)
• Frequency: Three times daily (morning, midday, and evening, roughly every 8 hours)
• Concentration: 2% (20 mg per mL)
• Bottle size: Typically 10 mL, which lasts approximately 6-8 weeks at standard dosing

How to Put in Dorzolamide Eye Drops Correctly

Proper technique makes a real difference in how well dorzolamide works and how much discomfort you experience:

1. Wash your hands thoroughly with soap and water
2. If you wear soft contacts, remove them first (wait 15 minutes after drops before reinserting)
3. Tilt your head back and pull your lower eyelid down to form a pocket
4. Hold the bottle upside down and squeeze to instill one drop into the pocket — do not touch the dropper tip to your eye or any surface
5. Close your eye gently and press on the inner corner (bridge of nose side) for 60-90 seconds — this reduces the bitter taste and improves absorption
6. If using other eye drops, wait at least 5 minutes before the next drop (some guidelines say 10 minutes for other IOP-lowering medications)

How Long Does Dorzolamide Take to Work?

Effects begin within about 3 hours of the first dose and last for approximately 8 hours — which is why three-times-daily dosing is required to maintain continuous IOP control around the clock. Dorzolamide does not cure glaucoma; it manages it. Stopping the drops will allow your IOP to rise again.

Is Dorzolamide a Controlled Substance?

No. Dorzolamide is not a controlled substance. It has no DEA schedule, no prescription quantity restrictions, and can be refilled without special authorization. It is a standard prescription-only medication available as a generic from multiple manufacturers.

How Much Does Dorzolamide Cost?

Without insurance or a coupon, generic dorzolamide 2% 10mL costs around $58 at retail. With a GoodRx coupon, it can be as low as $15.19. With insurance, most plans cover it as a Tier 1 or Tier 2 generic with copays in the $0-$30 range.

To understand the science behind how dorzolamide lowers eye pressure, see our detailed guide: How Does Dorzolamide Work? Mechanism of Action Explained. And if you're having trouble finding it at your pharmacy, medfinder can help you locate it near you.