Dorzolamide

2 medicines

Dorzolamide eye drops lower eye pressure in glaucoma, but although applied topically, they are absorbed enough to trigger sulfonamide-type allergic reactions, so anyone allergic to sulfa medicines should avoid them.

Cosopt

Dorzolamide, Timolol

2/0.5%

Cosopt is a eye care medication containing Dorzolamide + Timolol, available as 2/0.5% bottles.

from $46.18 / bottle View

Trusopt

Dorzolamide

2%

Trusopt is a eye care medication containing Dorzolamide, available as 2% bottles.

from $24.65 / bottle View

Key facts

  • Dorzolamide is a carbonic anhydrase inhibitor eye drop that reduces fluid production inside the eye. It is sold alone as Trusopt and combined with timolol as Cosopt.
  • It is usually applied as one drop in the affected eye up to three times daily; pressing gently on the inner corner of the eye after each drop limits how much reaches the rest of the body.
  • Although applied to the eye, enough dorzolamide is absorbed into the bloodstream to trigger the same allergic reactions as sulfa antibiotics. People with a sulfonamide allergy should avoid it.
  • Seek urgent care for sudden eye pain, a rapid change in vision, or facial or throat swelling.

What dorzolamide treats

Dorzolamide treats open-angle glaucoma and ocular hypertension, conditions where pressure inside the eye is too high and can damage the optic nerve over time. It is used alone or added to another pressure-lowering eye drop when one drop alone is not enough.

How dorzolamide works

The eye continuously produces a clear fluid called aqueous humor, made with the help of an enzyme called carbonic anhydrase. Dorzolamide blocks this enzyme in the tissue that produces the fluid, so less is made, and the pressure inside the eye falls.

Before you take it

  • Do not use dorzolamide if you are allergic to it or to any sulfonamide (sulfa) medicine.
  • Tell your prescriber about kidney disease, since dorzolamide is cleared by the kidneys and may need dose changes.
  • If you wear soft contact lenses, remove them before applying the drops and wait at least 15 minutes before putting them back in.
  • Using dorzolamide with an oral carbonic anhydrase inhibitor is generally avoided, since the effects add together.

Side effects

Common effects include stinging on application, a bitter or metallic taste, temporary blurred vision, and eye redness.

Stop and seek urgent medical care for any of these:

  • Sudden eye pain, swelling, or a rapid change in vision.
  • Signs of a severe allergic reaction, such as swelling of the face, lips, or throat, or difficulty breathing.
  • Severe skin rash or blistering.

Safety essentials

  • Sulfonamide cross-reactivity is the key risk: even as an eye drop, dorzolamide can cause the rash, blood disorders, or, rarely, severe skin reactions seen with sulfa antibiotics. Stop the drops and get medical help at the first sign of a rash or unusual bruising.
  • Have your eye pressure checked regularly, since dorzolamide alone may not protect vision long-term and additional treatment may be needed.
  • Anyone with corneal problems or previous eye surgery should be monitored closely, since dorzolamide can affect the cornea's fluid balance.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.