Timolol is a beta blocker that is very inexpensive and works well for glaucoma BUT I use it last in my choice of the 4 times of glaucoma drops because of the potential for major
side effects. It cannot be used in people with asthma or reactive airway disease, a history of slow heart rate (bradycardia) and can cause many problems like chronic cough, severe loss of energy, chronic nasal congestion (seems like sinus problem that won't go away), very cold extremeties, etc.