Medicines & Supplements A to Z > Cosopt


Last updated on 07/07/2021.

Overview   |   Dosage   |    Side Effects   |   Precautions  |   Tips  |   Where To Buy  

GENERIC NAME: Dorzolamide + Timolol


DRUG CLASS: Anti-glaucoma agents

SUB CLASS: Carbonic anhydrase inhibitors, Beta-blockers

USED FOR: Glaucoma, Ocular hypertension

– 2%/0.5% (eye drops)

What is Cosopt for?

Cosopt is the combination of Dorzolamide and Timolol, which are carbonic anhydrase inhibitor and beta-blocker respectively. The former decreases aqueous humor secretion, whereas the latter reduces aqueous humor production. The combined effect can lower intraocular pressure so as to treat glaucoma and ocular hypertension.

How to use it?

Cosopt is applied to the eyes. Instill 1 drop in affected eye(s) twice daily.  

Lie down or tilt your head back. With your index finger, pull down the lower lid of your eye. Hold the dropper close to your eye with the other hand, and drop 1 drop into your eyes between your lower lid and eyeball. Gently close your eyes. Place your index finger over the inner corner of your eye for 1 minute.

What are the side effects of Cosopt?

The common side effects of Cosopt include taste perversion, ocular burning and stinging, blurred vision, itchy eyes, or conjunctival hyperemia.

Who should not take Cosopt?

– People who are allergic to Dorzolamide, Timolol or any component of the formulation
– Patients with severe chronic obstructive pulmonary disease (COPD), or active/history of bronchial asthma
– Patients with sinus bradycardia, second- or third-degree heart block, heart failure, cardiogenic shock

Pharmacist Tips:

– Wash your hands with soap and water before and after using.
– Remove contact lenses prior to administration, and wait 15 minutes before reinserting.
– Separate administration of other ophthalmic agents by at least 10 minutes.
– Avoid driving or other activities requiring clear vision until drug effects are realized.

Common dosing schedule:
Timolol eye drops should be instilled one drop in the morning and one drop in the evening. 

This schedule is for reference only, adjustments may be made according to individual needs.

Some common medications Cosopt may interact with:
– Clonidine
– Calcium channel blockers, e.g. Verapamil, Diltiazem
– Beta-blockers, e.g. Metoprolol, Propranolol
– Carbonic Anhydrase Inhibitors, e.g Acetazolamide

Please notify your doctor or pharmacist if you are taking the above medication, dosage adjustments might be needed.

Where to buy Cosopt in Hong Kong?

In Hong Kong, Cosopt is a prescription only medicine, and requires a prescription from a doctor to be purchased in a pharmacy. It can also be obtained from doctors. To find a pharmacy near you, refer to the list of pharmacies (“Authorized Sellers of Poisons”) from the Hong Kong Department of Health.

For more information about drug names and ingredients, you can visit Hong Kong’s Drug Office at

Need more information?

For detailed information about the use of Cosopt in children, pregnancy and breastfeeding, and for questions about drug interactions, please check with your pharmacist or doctor.

Disclaimer: our goal is to provide you with the most relevant drug information and common dosage for Hong Kong. This information does not constitute medical advice. For specific treatment recommendations and advice, always discuss with your doctor or pharmacist, and follow the instructions included with your specific medicine.