Dorzolamide-Timolol

( Cosopt )

Medically Reviewed by Dr. Harshi Dhingra, M.D.

Last Reviewed: Nov 28, 2023

Warnings


Dorzolamide-Timolol (Cosopt) Risks, Warnings, and Complications


Dorzolamide and timolol can cause serious health problems in some people. Talk to your doctor or pharmacist about other treatment options if you are at an increased risk of complications from this combination of medicines. Some of the risks of using dorzolamide-timolol include:

  • SERIOUS BREATHING PROBLEMS: One of the medications in Cosopt, timolol, is a beta blocker. Beta blockers can cause narrowing of the airways and serious breathing problems in people with lung conditions such as asthma, chronic obstructive pulmonary disease (COPD), chronic bronchitis, and emphysema. Although only a small amount of the topical beta blocker is absorbed into the bloodstream, this is still a risk. Before starting dorzolamide-timolol, tell your doctor if you have ever had any lung problems.

  • WORSENING HEART PROBLEMS: Beta blocker drugs such as timolol can worsen heart failure and heart block. Rarely, the use of a beta blocker over a period of time can cause heart failure. Seek medical attention if you notice swelling in your lower legs, ankles, or feet, rapid weight gain, shortness of breath, especially when lying down or exercising, or a faster, slower, or irregular heartbeat. 

  • ALLERGIC REACTIONS: One of the medications in Cosopt, dorzolamide, is a sulfa drug and can cause life-threatening allergic reactions. Sulfa allergies can cause a severe skin reaction, liver damage, and problems with blood cells. Mild allergies to sulfa medications can cause eyelid pain or irritation. Stop using dorzolamide-timolol and contact your doctor immediately if you notice a serious skin rash, stomach pain, weakness, or generally feel unwell. 

    In addition, beta blockers, including timolol can increase your sensitivity to a variety of allergens and make you unresponsive to the usual doses of epinephrine (a medication used to treat severe allergic reactions).

    Before starting dorzolamide-timolol, tell your doctor if you have a sulfa allergy or a history of anaphylactic reactions (throat closing).

  • WORSENING MUSCLE WEAKNESS: Beta blocker medications like timolol can cause worsening muscle weakness. Before using this medicine, tell your healthcare provider if you have a muscle condition such as myasthenia gravis. Call your doctor immediately if you develop symptoms such as eyelid drooping, double vision, or general weakness while on this medicine. 

  • MASKING SYMPTOMS OF LOW BLOOD SUGAR: In people with diabetes, beta blocker medications such as timolol can mask (hide) the symptoms of hypoglycemia (low blood sugar). This risk is small with topical medications like dorzolamide-timolol. However, if you have diabetes and take medications to treat it, talk to your provider about how often you should check your blood glucose while using this medicine. 

  • MASKING SYMPTOMS OF THYROTOXICOSIS: Beta blockers like timolol can mask the symptoms of hyperthyroidism (overactive thyroid) and thyrotoxicosis (very high levels of thyroid hormones). Only very small amounts of dorzolamide-timolol are absorbed into the bloodstream from eye drops, and the risk of this happening is low. Nonetheless, before using this medicine, tell your healthcare provider if you have a history of thyroid problems. 

  • KIDNEY AND LIVER PROBLEMS: Oral carbonic anhydrase inhibitors may not be safe for people with renal or hepatic impairment (reduced kidney or liver function). Although only small amounts of dorzolamide are absorbed into the bloodstream from eye drops, tell your doctor if you have any kidney or liver problems before starting this topical ophthalmic drug.

  • EYE PROBLEMS: Dorzolamide can increase the risk of corneal swelling and thinning of the cornea (the protective covering in front of the eye). Also, multi-use containers of topical eye medications are associated with a risk of infections such as bacterial keratitis due to contamination. Symptoms of an eye infection may include eye pain, redness, excessive tearing, and serious vision problems like blurred vision and decreased vision. The risk of eye infection is higher in people with corneal disease. Before starting Cosopt, tell your provider if you have corneal problems. Take precautions to avoid contamination of your eye medication by handling the dropper carefully.


Precautions Before Starting Dorzolamide-Timolol (Cosopt)

Tell your doctor if you have had an allergic reaction to timolol (Timoptic), dorzolamide (Trusopt), any of the active or inactive ingredients in dorzolamide-timolol ophthalmic solution, sulfa drugs, or any other medications. Your pharmacy can give you a list of ingredients.

Give your doctor or pharmacist a complete list of all the medicines you are taking, including prescription drugs, nonprescription medicines, other eye drops, vitamins, supplements, and herbal products. This can help avoid possible interactions between dorzolamide-timolol and your other medicines. 

Give your doctor a complete medical history. Dorzolamide-timolol may not be suitable for people with certain health conditions, including lung conditions like asthma, chronic obstructive pulmonary disease (COPD), chronic bronchitis, emphysema, diabetes, heart disease, severe allergic reactions, hyperthyroidism (overactive thyroid gland), myasthenia gravis, kidney disease, and liver disease. 

Tell your doctor if you are pregnant, could be pregnant, are planning a pregnancy, or are breastfeeding.

Precautions During Use of Dorzolamide-Timolol (Cosopt)

Keep all your healthcare appointments while using dorzolamide-timolol. Your doctor may want to adjust your dose and monitor you for adverse effects.

If you are using other eye drops, apply them at least 10 minutes away from dorzolamide-timolol.

If you wear contact lenses, remove them before instilling dorzolamide-timolol ophthalmic solution. Wait at least 15 minutes before putting your contact lenses back in. Cosopt contains a preservative called benzalkonium chloride that can damage soft contact lenses. Cosopt PF is a preservative-free version. 

Side effects of dorzolamide-timolol, such as eye irritation, can affect your ability to see clearly. Do not drive, operate heavy machinery, or engage in any hazardous activities until you know how this medication affects you.

Tell your healthcare professional if you become pregnant while using dorzolamide and timolol.

Let your doctors know you are using dorzolamide-timolol before any surgery, including dental procedures.

If you have an eye infection, eye injury, or are having eye surgery, ask your healthcare professionals if you can continue using the same bottle of dorzolamide-timolol.

Dorzolamide-Timolol (Cosopt) Drug Interactions

Concomitant administration of dorzolamide and timolol with certain other medicines can affect how the medicines work. Possible interactions between dorzolamide-timolol and other medicines can increase the risk of severe adverse effects. Your doctor may change the dose of your medications, choose different medications, or monitor you carefully for side effects if there are known interactions between dorzolamide-timolol and your other medicines.

The following medications can have interactions with dorzolamide-timolol:

  • Beta blockers such as atenolol (Tenormin), metoprolol (Lopressor, Toprol XL), labetalol (Normodyne), propranolol (Inderal), and nadolol (Corgard)
  • Carbonic anhydrase inhibitors such as acetazolamide (Diamox), methazolamide (GlaucTabs, Neptazane), and dichlorphenamide (Danaride)
  • Calcium channel blockers such as felodipine (Plendil), diltiazem (Cardizem, Tiazac, Dilacor, others), nicardipine (Cardene), amlodipine (Norvasc), nimodipine (Nimotop), isradipine (DynaCirc), nifedipine (Adalat, Procardia), nisoldipine (Sular), and verapamil (Calan, Verelan, Isoptin)
  • Diuretics or water pills
  • Medications used to treat high blood pressure such as clonidine (Catapres, Catapres-TTS) and  reserpine (Serpasil, Serpalan, Serpatabs)
  • Heart medications such as digoxin (Lanoxin)
  • Medications used to treat irregular heart rhythms, such as quinidine (Quinidex)
  • Salicylate pain relievers such as aspirin, diflunisal (Dolobid), magnesium salicylate (Doan's, others), choline salicylate (Arthropan), choline magnesium trisalicylate, and salsalate (Disalcid, Argesic, Salgesic)

The above list may not include all the possible interactions of dorzolamide-timolol. Give your doctor or pharmacist a complete list of your medications, including prescription drugs, non-prescription medicines, dietary supplements, and herbal remedies. Also, tell your healthcare provider if you smoke, drink alcohol, or use recreational drugs because some of these substances can cause serious health complications when used with prescription and over-the-counter medicines.