Prescription medication · CAI / Beta-Blocker Combination (Ophthalmic)

dorzolamide/timolol

Also sold as Cosopt. Cosopt is used to lower high pressure in your eyes.

Data updated 2026-05-15

4,073
FDA reports
3
InteractionsFew interactions
Rx
Availability

What the data shows

dorzolamide/timolol (Cosopt) is a prescription CAI / Beta-Blocker Combination (Ophthalmic), with 4,073 FDA adverse-event reports on file, with 3 documented drug interactions.

Reporting volume reflects how widely a drug is used and studied, not how dangerous it is, a FAERS report documents a temporal association, never proof of cause.

dorzolamide/timolol (Cosopt) is a prescription CAI / Beta-Blocker Combination (Ophthalmic). Cosopt is used to lower high pressure in your eyes.

Cosopt is an eye drop that lowers pressure inside the eye. It combines two medicines to treat glaucoma and high eye pressure.

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What it does

Cosopt is used to lower high pressure in your eyes.

Common side effects

Bitter, sour, or unusual taste, Eye burning or stinging, Redness of the eye

Key warnings

Cosopt contains timolol, which can cause breathing problems like asthma.

The sections below are summarized in plain English from dorzolamide/timolol's FDA-approved prescribing information. They describe what the official label says, and are not personal medical advice.

How It Works

Cosopt has two medicines. Dorzolamide lowers eye pressure by reducing fluid production in the eye. Timolol lowers eye pressure by blocking certain receptors in the eye.

Side Effects (from patient reports)

Based on 4,073 FDA adverse event reports.

Most-reported reactions

Adverse reactions in FAERS for dorzolamide/timolol, by number of reports

reports

What this shows Bars show how often each reaction was reported, not how likely it is to happen, a report records a temporal association, never proof that the drug caused it.

Source FDA Adverse Event Reporting System (FAERS)

Serious Warnings

Cosopt contains timolol, which can cause breathing problems like asthma. If you have asthma or severe lung disease, you should not use Cosopt. Cosopt can also cause heart problems, including heart failure. If you have heart problems, talk to your doctor before using Cosopt. Cosopt contains dorzolamide, a sulfonamide. Rarely, severe reactions to sulfonamides, including fatal reactions, have occurred. If you have a sulfonamide allergy, you should not use Cosopt.

Known Drug Interactions

minor clonidine

7.8 Clonidine Oral beta-adrenergic blocking agents may exacerbate the rebound hypertension which can follow the withdrawal of clonidine.

Mechanism: The beta-blocker in the eye drops can make blood pressure rise even higher if you suddenly stop taking your clonidine medication.

minor timolol

7.7 CYP2D6 Inhibitors Potentiated systemic beta-blockade (e.g., decreased heart rate, depression) has been reported during combined treatment with CYP2D6 inhibitors (e.g., quinidine, SSRIs) and timolol. There have been no reports of exacerbation of rebound hypertension with ophthalmic timolol maleate.

Mechanism: Using two medications that both contain timolol can lead to an overdose, which may slow your heart rate down too much or cause low blood pressure.

minor dorzolamide

7.2 High-Dose Salicylate Therapy Although acid-base and electrolyte disturbances were not reported in the clinical trials with dorzolamide hydrochloride ophthalmic solution, these disturbances have been reported with oral carbonic anhydrase inhibitors and have, in some instances, resulted in drug interactions (e.g., toxicity associated with high-dose salicylate therapy).

Mechanism: Taking two drugs that both contain dorzolamide can cause the medicine to build up in your body and lead to chemical imbalances in your blood.

This is a plain-language summary of FDA-label interaction records and does not provide individual medication-combination directions.

Common Questions

Can I use Cosopt with other eye drops?
Yes, but wait at least 5 minutes between using Cosopt and other eye drops.
What if my eye gets irritated after using Cosopt?
Some eye irritation is common. If it's severe or doesn't go away, contact your doctor.
Can I wear contact lenses while using Cosopt?
Talk to your doctor about wearing contact lenses while using Cosopt.
How long does it take for Cosopt to start working?
Cosopt starts working quickly to lower eye pressure, but it may take a few weeks to see the full effect.
What should I do if I accidentally swallow Cosopt?
Contact your doctor or poison control center right away.
Can Cosopt affect my blood pressure?
Yes, Cosopt can lower blood pressure in some people.
Will Cosopt cure my glaucoma?
No, Cosopt does not cure glaucoma, but it can help control eye pressure.
Can I drive after using Cosopt?
Cosopt can cause blurred vision in some people. If this happens, do not drive or operate machinery until your vision is clear.
What are the signs of an allergic reaction to Cosopt?
Signs of an allergic reaction include rash, itching, swelling, and difficulty breathing. If you have any of these symptoms, get medical help right away.
How long can I use Cosopt after opening the bottle?
You can use Cosopt until the expiration date on the bottle, even after opening it.
What are the common side effects of dorzolamide/timolol?
The registry lists Bitter, sour, or unusual taste, Eye burning or stinging, Redness of the eye, Blurred vision, Superficial punctate keratitis (small spots on the cornea) among the most-reported FAERS reaction terms for dorzolamide/timolol. The compiled record contains 4,073 FDA adverse-event reports. These counts are not an individual symptom assessment.
Does dorzolamide/timolol interact with other medications?
The registry has 3 documented interaction rows for dorzolamide/timolol. Notable source-record pairings include clonidine, timolol, dorzolamide. These rows are not a complete medication review.
What drug class is dorzolamide/timolol?
dorzolamide/timolol belongs to the CAI / Beta-Blocker Combination (Ophthalmic) drug class. It requires a prescription (Rx). Cosopt is used to lower high pressure in your eyes.
What pregnancy or breastfeeding source fields are listed for dorzolamide/timolol?
The FDA label for dorzolamide/timolol contains product-specific pregnancy or breastfeeding language. PlainMeds does not apply that source text to an individual.

Related Medications in CAI / Beta-Blocker Combination (Ophthalmic)

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bevacizumab (ophthalmic)

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bimatoprost

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brimonidine ophthalmic

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What the FDA Data Shows for dorzolamide/timolol

The FDA label for dorzolamide/timolol (sold under brand names such as Cosopt) classifies it as a prescription-only medication in the CAI / Beta-Blocker Combination (Ophthalmic) class. Cosopt is used to lower high pressure in your eyes. Official labeling lists 6 commonly reported side effects, including Bitter, sour, or unusual taste, Eye burning or stinging, Redness of the eye.

Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 4,073 voluntary reports. The database also lists 3 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated minor severity. Acquisition-cost data is surveyed weekly by CMS and updated as manufacturers report changes.

Report counts do not establish causation, a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information are separate source-record fields. This page is a public FDA/CMS registry and does not provide medical, treatment, substitution, or medication-change directions.

Data Sources

Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS).

FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. This registry does not provide medication decisions.

Last updated: April 17, 2024

PlainMeds is rendered directly from FDA openFDA/FAERS extracts, DailyMed labels, and CMS drug-pricing files, no number is typed in by an editor. FAERS counts, recalls, shortages, and price figures on this page are queried live from those federal extracts. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error. Data current as of 2026-05-15. Primary sources: openFDA / FAERS, DailyMed and CMS Part B ASP.

Read our methodology - how this data is sourced, computed, and verified.

Data currency: FDA FAERS adverse-event reports through 2025, CMS NADAC acquisition-cost pricing effective December 2024, compiled from the source snapshot dated . See our methodology for per-source dates and refresh cadence. Spot a figure that looks wrong? Report a data issue.

All federal data sources used on this page