Medical treatments for BPH: Comparing long-term side-effects

This long-term study evaluated the side-effects of drugs such as doxazosin and finasteride, commonly used to treat urinary symptoms in men with benign prostatic hyperplasia (BPH).

Researchers concluded that adverse effects associated with these drugs mainly occur within the first year of treatment. 

Drugs that are commonly prescribed for treating urinary symptoms in BPH include alpha-blockers such as doxazosin (Cadura) and 5 alpha-reductase inhibitors such as finasteride (Proscar, Propecia). Both have been associated with side-effects within the first year of treatment, when compared to placebo (a substance with no effect used as a control). The six most frequently reported side-effects include dizziness, low blood pressure associated with posture change (orthostatic hypotension), weakness, impotence, decreased libido and abnormal ejaculation. This study evaluated these common side-effects during long-term follow-up.

A total of 3,047 men with BPH were randomly assigned to receive treatment with either placebo, doxazosin, finasteride, or combination therapy (doxazosin and finasteride). Commonly reported side-effects were followed-up on for an average of 4.5 years.

Side-effects were most commonly reported within the first year of treatment. This was true for all treatments. Overall, reports of side-effects were most common among men receiving combination therapy.

When compared to placebo, treatment with doxazosin was associated with a two-fold increase in reports of dizziness and postural low blood pressure in the first year of treatment. Postural low blood pressure was also reported among doxazosin users after the first year of treatment (but less frequently than during the first year).

Combination therapy was associated with a three-fold increase in reports of dizziness, weakness, and postural low blood pressure in the first year of treatment (compared to placebo). Men receiving combination therapy were also more likely to experience dizziness after the first year of treatment.

Adverse effects related to sexual function were significantly increased in treatment with finasteride alone and in combination therapy. Compared to placebo, the reported rates of impotence, decreased libido and abnormal ejaculation were about twice as high for finasteride, and between 2 to 5 times higher for combination therapy. After the first year of treatment, only abnormal ejaculation was commonly reported, and only among men receiving combination therapy.

Researchers concluded that adverse effects to doxazosin or finasteride occur mainly early in the course of treatment, mostly within the first year. Doxazosin is associated mainly with dizziness and postural low blood pressure, while finasteride mainly affects sexual function. However, the rate of all reported side-effects decreases with time.