Also for treating benign prostatic hyperplasia, and pulmonary arterial hypertension.
Common Side Effects: headache, muscle pain, flushed skin, nausea, stomach discomfort or pain, indigestion, burping, acid reflux, back pain, pain in limbs and extremities, flushing, hypertension (or uncommonly hypotension), stuffy/runny nose, dizziness, peripheral edema, fatigue, urinary or respiratory tract infection, diarrhea or constipation.
Rare Side Effects: penis damage, vision problems, sudden (temporary!) deafness.