Why would a dermatologist prescribe me spironolactone 50mg tablets for acne when i told him i'm on lisinopril-hctz 20/12.5mg tablets for hypertension?

Hypertension: Spironolactone should have no effect on your other listed med. That said, it is a bit surprising that a 32 year old woman has hypertension. You should check your blood pressure on alternate mornings and evenings. There are many stores (not Pharmacy) that sell you a small instrument that measures your blood pressure at your wrist. It is a lot less expensive than the Pharmacy- about 50-70% less cost

Anti-androgen: Spironolactone is by far the best way to control acne for adult women because it affects the hormones which cause it. For entirely different reasons, it is an excellent addition to the meds you take for BP. Not expensive, very well tolerated and safe, it should not be used if pregnant or in kidney failure. Do NOT take potassium [KCl] pills if you take spironolactone. Dose varies from 25 to 200mg.