Timolol maleate is a non-selective beta-adrenergic receptor blocker. In its oral form (Blocadren®), it is used to treat high blood pressure and prevent heart attacks, and occasionally to prevent migraine headaches. In its opthalmic form (Timoptic®), it is used to treat open-angle and occasionally secondary glaucoma.
The most serious possible side effects include cardiac arrhythmias and severe bronchospasms. Timolol can also lead to fainting, stroke, congestive heart failure, depression, confusion, and impotence.