Ziac is bisoprolol and hydrochlorothiazide.

Hydrochlorothiazide is a sulfonamide and can be absorbed systemically. Sulfonamides can produce severe, possibly fatal, reactions such as toxic epidermal necrolysis and Stevens-Johnson syndrome.

Contra-indicated in patients with cardiogenic shock, overt cardiac failure, second or third degree AV block, and marked sinus bradycardia.