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Overview: Dorzolamide/timolol is an eye drop used to lower high pressure inside the eye in people with open-angle glaucoma or ocular hypertension. It combines two medicines that work in different ways to reduce the amount of fluid in the eye. Common side effects include burning or stinging after the drop is applied, a bitter taste in the mouth, and blurry vision. Call your health care provider right away if you have eye itchiness, shortness of breath or trouble breathing, dizziness, feeling lightheaded, fainting, or a racing heart.

Uses

What is dorzolamide/timolol used for?

Dorzolamide/timolol is commonly used to lower pressure inside the eye in people with open-angle glaucoma or ocular hypertension. These conditions cause increased pressure inside the eye.

Dorzolamide/timolol may also be used for other conditions as determined by your health care provider.

How does dorzolamide/timolol work (mechanism of action)?

High pressure inside the eye can lead to nerve damage and vision loss. This medicine contains two active ingredients: dorzolamide, which is a carbonic anhydrase inhibitor, and timolol, which is a beta-blocker. Both ingredients work in slightly different ways to decrease the amount of fluid in the eye. This helps to lower pressure inside the eye. 

How is dorzolamide/timolol supplied (dosage forms)?

Brands and other names

  • Cosopt
  • Cosopt PF

Dosage forms and strengths

  • 2%/0.5% eye drops 

How should I store dorzolamide/timolol?

Dorzolamide/timolol should be stored at temperatures between 68 F and 77 F (20 C and 25 C). Do not freeze the medicine or keep it in direct sunlight.

Some dorzolamide/timolol products are packaged in single-use containers wrapped in foil to protect them from light. When you open the foil pouch, write down the date and keep the remaining containers in the foil pouch until you are ready to use them. Throw away any unused medicine 15 days after you open the pouch. 

Ask your pharmacist if you are unsure how to store your dorzolamide/timolol eye drops.

Side Effects

What are the most common side effects of dorzolamide/timolol?

The most common side effects of dorzolamide/timolol are listed below. Tell your health care provider if you have any of these side effects that bother you.

  • Burning, stinging, or discomfort after you put the drop in your eye
  • Bitter or unusual taste in your mouth after you put the drop in your eye
  • Other eye discomforts, such as redness, itching, tearing, dryness, or feeling like something is in your eye 
  • Blurry vision
  • Headache
  • Vision that is sensitive to bright light

There may be other side effects of dorzolamide/timolol that are not listed here. Contact your health care provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088 (800-332-1088). In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of dorzolamide/timolol?

While less common, the most serious side effects of dorzolamide/timolol are described below, along with what to do if they happen.

Eye or Eyelid Inflammation. Dorzolamide/timolol may cause severe inflammation of your eye or the inside lining of your eyelid (conjunctivitis). In some cases, this may be a sign of an allergic-type reaction. Stop using dorzolamide/timolol and tell your health care provider right away if you have any of the following symptoms of conjunctivitis.

  • Redness or pink color in the white of your eye
  • Eye itchiness
  • Swollen eyelid
  • Eye discharge or crusting
  • Watery eye
  • Eye pain
  • Vision changes that do not go away

New or Worsening Heart Failure. Dorzolamide/timolol mainly works in the eye, but may be absorbed into the blood and affect other parts of the body, such as the heart. While rare, dorzolamide/timolol may cause or worsen heart failure, which is a condition where the heart is not pumping as well as it should. Tell your health care provider right away if you have any of the following symptoms of heart failure.

  • Shortness of breath or trouble breathing, especially while lying down
  • Swelling in your feet, ankles, or legs
  • Unusually fast weight gain
  • Unusual tiredness

Breathing Problems. While rare, dorzolamide/timolol may cause the muscles around the airways to tighten (bronchospasm). Stop using dorzolamide/timolol and get help right away if you have sudden breathing problems.

Low Blood Pressure. Dorzolamide/timolol may rarely cause low blood pressure (hypotension). If you feel faint or dizzy, lie down. Tell your health care provider right away if you have any of the following symptoms of low blood pressure.

  • Dizziness, feeling lightheaded, or fainting
  • Confusion
  • Feeling weak or tired

Heart Rate Changes. Dorzolamide/timolol may rarely make your heart beat slower than normal (bradycardia). Call your health care provider right away if you have any of the following symptoms. 

  • Feeling lightheaded, dizziness, or fainting
  • Confusion
  • Feeling weak or easily tired 
  • Chest pain
  • Shortness of breath

Severe Allergic Reactions. Dorzolamide/timolol may cause allergic reactions, which can be serious. Stop using dorzolamide/timolol and get help right away if you have any of the following symptoms of a serious allergic reaction.

  • Breathing problems or wheezing
  • Racing heart
  • Fever or general ill feeling
  • Swollen lymph nodes
  • Swelling of the face, lips, mouth, tongue, or throat
  • Trouble swallowing or throat tightness
  • Itching or skin rash
  • Bumps on the skin called hives that can be red, pink, white, or brown depending on your skin tone
  • Nausea or vomiting
  • Dizziness, feeling lightheaded, or fainting
  • Stomach cramps
  • Joint pain

Warnings & Precautions

Who should not use dorzolamide/timolol?

Allergies to Ingredients. People who are allergic to any of the following should not use dorzolamide/timolol.

  • Dorzolamide
  • Timolol
  • Cosopt 
  • Cosopt PF
  • Any of the ingredients in the specific product dispensed

Your pharmacist can tell you all of the ingredients in the specific dorzolamide/timolol products they stock.

Breathing Problems. Dorzolamide/timolol should not be used by people with asthma or severe chronic obstructive pulmonary disease (COPD).

Certain Heart Problems. Dorzolamide/timolol should not be used by people with the following heart conditions.

  • Heart failure, which is when your heart is not pumping as well as it should
  • Bradycardia, which is when your heart is beating too slow
  • Heart block, which is when the electrical signals in your heart are slowed
  • Cardiogenic shock, which is when your heart cannot pump enough blood to the rest of your body

What should I know about dorzolamide/timolol before using it?

Do not use dorzolamide/timolol unless it has been prescribed to you by a health care provider. Use it as prescribed.

Do not share dorzolamide/timolol with other people, even if they have the same condition as you. It may harm them.

Keep dorzolamide/timolol out of the reach of children.

Dorzolamide/timolol is an eye drop medicine. Make sure that you or a caregiver understands how to properly administer eye drops. If you have any questions, talk to your health care provider.

If you use more than one eye medicine, use them at least 5 minutes apart. Ask your health care provider if you are unsure about when to use your eye medicines.

Eye infections may occur if your dorzolamide/timolol eye drop container gets contaminated with bacteria or other germs. In some cases, eye infections may become severe and lead to vision loss. To help prevent eye infections, be careful not to let the tip of the eye drop container touch your eye, fingers, or any other surfaces. Wash your hands before each use. Tell your health care provider right away if you have an eye infection, eye injury, vision changes, or need to have eye surgery. Symptoms of an eye infection may include pink or itchy eyes, blurry vision or irritation, eye discharge, swollen eyelids, and fever.

Remove contact lenses before using dorzolamide/timolol eye drops. Then wait at least 15 minutes before you put your contacts back in.

Some dorzolamide/timolol products come in single-use containers. These products are preservative-free, which means they can go bad quickly after the container is opened. Use the medicine as soon as you open it, in one or both eyes as prescribed, then discard the container. Do not save any leftover medicine.

What should I tell my health care provider before using dorzolamide/timolol?

Tell your health care provider about all of your health conditions and any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. This will help them know if dorzolamide/timolol is right for you.

In particular, make sure that you discuss any of the following.

Current and Past Health Conditions. Tell your health care provider if you have any of the following.

  • Heart problems
  • Breathing problems
  • Problems with blood circulation
  • Diabetes
  • Thyroid disorders
  • Myasthenia gravis
  • Problems with your cornea (the clear layer that covers the front of the eye)
  • Angle-closure glaucoma
  • Severe kidney problems
  • Liver problems

Past or Planned Surgery. Using dorzolamide/timolol may raise the risk of problems following a certain type of eye surgery for glaucoma. Also, using dorzolamide/timolol may increase the risks with medicines commonly used during major surgery (anesthesia). Tell your health care provider if you had eye surgery in the past or if you have major surgery planned.

Other Medicines and Supplements. Dorzolamide/timolol may interact with other medicines and supplements. Before using dorzolamide/timolol, tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using. See the Interactions section for more details.

Sulfa Allergy. Some people who have a sulfa allergy may also be allergic to medicines that contain dorzolamide. A sulfa allergy is a rash or more serious reaction to sulfa, or sulfonamide, medicines. Examples of sulfa medicines are sulfamethoxazole, sulfadiazine silver, or sulfasalazine. Tell your health care provider if you have any allergies to medicines. Your health care provider can help you decide if it is safe for you to use dorzolamide/timolol.

Pregnancy. It is not known if or how dorzolamide/timolol could affect pregnancy or harm a fetus. Tell your health care provider if you are or plan to become pregnant.

Breastfeeding. Timolol passes into breast milk, but it is not known if dorzolamide passes into breast milk. Tell your health care provider if you are breastfeeding or plan to breastfeed. Your health care provider will let you know if you should use dorzolamide/timolol while breastfeeding.

Interactions

Does dorzolamide/timolol interact with foods or drinks?

There are no known interactions between dorzolamide/timolol and foods or drinks.

It is unknown if drinking alcohol will affect dorzolamide/timolol.

Does dorzolamide/timolol interact with other medicines (drug interactions)?

Always tell your health care provider about any prescription or over-the-counter (OTC) medicines, vitamins/minerals, herbal products, and other supplements you are using.

 In particular, make sure that you discuss if you are using any of the following medicines before starting dorzolamide/timolol.

  • A carbonic anhydrase inhibitor that you take by mouth, such as zonisamide (Zonegran and others) or acetazolamide (Diamox)
  • A salicylate, such as aspirin or bismuth subsalicylate (Pepto Bismol)
  • A beta-blocker that you take by mouth, such as atenolol (Tenormin) or metoprolol (Lopressor, Toprol XL, and others), which is a medicine commonly used for high blood pressure or certain heart conditions
  • Another beta-blocker eye drop, such as levobunolol (AKBeta, Betagan) or betaxolol (Betoptic)
  • A calcium channel blocker, such as nifedipine (Procardia), which is a medicine commonly used for high blood pressure or certain heart conditions
  • Digoxin (Lanoxin), which is a medicine used to treat irregular heartbeat and some types of heart failure
  • Quinidine, which is a medicine used to control your heart rate or rhythm (antiarrhythmic)
  • A selective serotonin reuptake inhibitor (SSRI), such as fluoxetine (Prozac), which is a medicine commonly used for anxiety and depression
  • Epinephrine injection (Epipen, Auvi-Q, and others)

Some other medicines may alter the blood levels of dorzolamide/timolol. Tell your health care provider about all medicines that you take or have recently taken.

This may not be a complete list of medicines that can interact with dorzolamide/timolol. Always check with your health care provider.

Does interact with other drugs you are taking?

Enter your medication into the WebMD interaction checker

Overdose/Missed Dose

What should I do if I accidentally use too much dorzolamide/timolol?

If you or someone else has used too much dorzolamide/timolol, get medical help right away, call 911, or contact a Poison Control center at 800-222-1222.

What should I do if I miss a dose of dorzolamide/timolol?

If you miss a dose, use it as soon as you remember. If it is almost time for your next dose, skip the missed dose and only use the next dose. Do not use double or extra doses.