Cosopt is timolol and dorzolamide; Timolide is timolol and hydrochlorothiazide. Dorzolamide and hydrochlorothiazide are sulfonamides and can be absorbed systemically. Sulfonamides can produce severe, possibly fatal, reactions such as toxic epidermal necrolysis and Stevens-Johnson syndrome.

Cutaneous side-effects of beta-receptor blockers are clinically polymorphous. They apparently appear after several months of continuous therapy.