There are three primary types of drugs used to relieve the symptoms of benign prostatic hyperplasia, or BPH.

5-Alpha Reductase Inhibitors
One class of medication, called 5-alpha reductase inhibitors, decreases the size of the prostate by blocking an enzyme that converts testosterone into a more potent hormone called dihydrotestosterone, or DHT, which accumulates in the prostate. When the enzyme is blocked, growth slows and, over time, the prostate gland may even shrink. It is important to remember that these medications can take up to six months to improve urinary function. Side effects are rare, but include impotence, decreased libido, decreased ejaculate volume, and breast enlargement.

Alpha Blockers
A second class of medications used to treat BPH are alpha blockers. These medications relax the smooth muscle of the prostate and bladder neck. For many men, alpha blockers can relieve pressure, improve urine flow, and reduce symptoms within days. However, there are several possible side effects, including dizziness, headache, fatigue, reduced blood pressure, and retrograde ejaculation.

Some research suggests that combining a 5-alpha reductase inhibitor with an alpha blocker can more effectively treat symptoms, improve urinary flow, and enhance quality of life.

PDE5 Inhibitors
A third type of medication used to treat BPH symptoms is a PDE5 inhibitor. Given on a daily basis, the PDE5 inhibitor tadalafil has been shown to improve symptoms related to BPH and impotence. This medication may be particularly effective for men with these issues. Side effects can include facial flushing, headache, back pain, nasal congestion, and dyspepsia. This medication should not be taken with nitrates.