Forzest 20 mg can treat erectile dysfunction and may also be used for benign prostatic hyperplasia (BPH); some sources also list pulmonary arterial hypertension (PAH) as a tadalafil use, though Forzest 20 mg is most commonly marketed for ED. What it treats Erectile dysfunction (ED): helps men achieve and maintain an erection during sexual activity. Benign prostatic hyperplasia (BPH): may Forzest 20mg urinary symptoms from an enlarged prostate. Pulmonary arterial hypertension (PAH): tadalafil is used for PAH in general, but this depends on the formulation and doctor’s prescription. Important note Forzest contains tadalafil, and it should not be used with nitrate medicines for chest pain because that can cause a dangerous drop in blood pressure.