Drug Interactions With Dorzolamide/Timolol
Dorzolamide/timolol may decrease the effectiveness of injectable epinephrine when used to treat allergic reactions. If you have a serious allergy that may require treatment with epinephrine, dorzolamide/timolol might not be a good choice for you.
It is dangerous to combine methacholine with dorzolamide/timolol. Doing so could cause severe, asthma-like breathing problems that are not easily corrected. These drugs should never be combined.
Other Beta Blockers
Dorzolamide/timolol contains a beta blocker. Caution should be used if dorzolamide/timolol is combined with other beta blockers, especially oral beta blockers (taken by mouth). Such combinations may increase the risk of side effects. In addition, two different beta blocker eye drops should not be taken at the same time.
Other Carbonic Anhydrase Inhibitors
Dorzolamide/timolol contains a carbonic anhydrase inhibitor. Even though it is an eye drop, some of the medication is absorbed into the rest of the body. Due to the possibility of increased side effects, dorzolamide/timolol should not be combined with another carbonic anhydrase inhibitor.
Combining reserpine with a beta blocker can increase the risk of serious side effects. You may need to be monitored closely if you take these drugs together. In some cases, dorzolamide/timolol should not be combined with reserpine.
Other Eye Medications
If you take other eye medications, be sure to separate your dorzolamide/timolol dosage from that of the other medication(s) by at least 10 minutes.
There have been rare reports of serious drug interactions (resulting in serious problems) in people taking high-dose salicylates and oral carbonic anhydrase inhibitors together. The risk of such problems is probably extremely small for dorzolamide/timolol, since it is given as an eye drop, especially if combined with low or normal doses of salicylates.