This Drug Class Treats BPH but Has Sexual Side Effects

Prostate complications can be common, especially among the over-50 crowd. One of the most prevalent conditions, benign prostatic hyperplasia (BPH), or prostate enlargement, affects at least 14 million men in the United States. As its name suggests, BPH is noncancerous, but its symptoms can be exhausting, if not debilitating. Symptoms include difficulty urinating, nocturia, pain after ejaculating and urinating, urinary incontinence, and increased risk of urinary tract infections (UTIs).

For people in the early stages of BPH, doctors may prescribe a group of drugs known as 5-alpha reductase inhibitors, such as finasteride, to reverse prostate growth. However, for some patients, the cure for one ailment could be the cause of another.

What is BPH exactly?

The prostate, a golf-ball-sized gland located between the bladder and base of the penis, produces some of the fluid in semen and goes through two growth spurts during a man's lifetime.

The first stage occurs in early puberty when the gland doubles in size, and the second happens around age 25 and continues indefinitely.

For some folks, the incremental increase that occurs in this second stage is never an issue. But for others, excessive enlargement, or BPH, causes the prostate to squeeze the urethra and inhibit urine and ejaculate flow. As the urethra works harder to push liquids out, it can also strain the bladder. Over time, the bladder muscles can wear out and become weaker, causing additional issues.

The cause of BPH is unknown, but unlike prostatitis—another condition involving an enlarged prostate—it is not caused by infection. BPH most likely occurs due to age-related changes to sex hormone levels such as testosterone.

According to Mayo Clinic, BPH symptoms can include:

• Frequent or urgent need to urinate
• Nocturia, or getting up to urinate frequently during the night
• Pain after urinating or ejaculating
• Difficulty starting urine flow
• Weak urine stream
• Dribbling at the end of urination
• Difficulty completely emptying the bladder
• Still feeling the urge to urinate after you just urinated
• Urinary incontinence

Though less common, urinary retention or the inability to urinate is also experienced by some people. This symptom can increase a person's susceptibility to UTIs, bladder stones, bladder damage and kidney damage.

For patients who are unable to urinate, a doctor can insert a catheter to drain the bladder. In severe cases, surgery may be necessary.

5-alpha reductase inhibitors and how they work

The enzyme 5-alpha reductase helps convert testosterone into the androgen dihydrotestosterone (DHT), which contributes to prostate growth, male-pattern hair loss and facial hair growth. Finasteride and similar drugs work by blocking 5-alpha reductase and decreasing DHT production.

Research shows finasteride can decrease prostatic DHT levels by about 90 percent and serum DHT by as much as 70 percent. Subsequently, it can halt prostate enlargement and gradually shrink the gland.

One study published in the New England Journal of Medicine found men taking 5 milligrams of finasteride every day for 12 months experienced, on average, a 19 percent decrease in prostatic volume. Men who took 1 mg of finasteride per day had an 18 percent decrease. Generally, the medication takes effect in four to six months.

As the prostate shrinks, so, too, does pressure on the bladder and the urethra. In the NEJM study, researchers found a 5-mg daily dose significantly decreased urinary symptoms, though patients taking a 1-mg daily dose experienced little difference.

However, finasteride's effects last only as long as the patient continues taking it. When a person stops taking the medication, the prostate begins to regrow within a few months. It is not recommended for men with normal-size prostates or those with severe enlargement. For advanced BPH that significantly affects a person's quality of life, doctors might recommend surgery instead.

Finasteride's side effects

Paul Thompson, M.D., a Fort Worth, Texas-based urologist and surgeon and the chief medical officer for Launch Medical, a Los Angeles men's sexual health company, said he does not generally recommend 5-alpha reductase inhibitors for BPH but sometimes prescribes them for hair loss. The latter treatment involves a 1-mg daily dose, which is less likely to produce side effects than the 5-mg daily dose recommended for BPH.

People taking a low dose who do experience side effects generally see their symptoms dissipate after stopping the treatment. This is not always the case for people on higher doses.

"Side effects can include decreased libido, erectile dysfunction, decreased volume of ejaculate fluid [semen], gynecomastia [enlargement of breast tissue], and depression or anxiety," said Kelly Casperson, M.D., a board-certified urologist, founder of Pacific Northwest Urology Specialists in Bellingham, Washington, and medical advisor at the Body Agency.

Some research suggests an impact on fertility is thought to be caused by the side effects mentioned above.

People taking a low dose who do experience side effects generally see their symptoms dissipate after stopping the treatment.

According to information published by the National Institutes of Health, another potential side effect is orthostatic hypotension—a form of low blood pressure—which is most likely to occur in patients who are also taking blood pressure medication. Some patients have reported dizziness, weakness, dyspnea (difficult or labored breathing), rhinitis (nasal obstruction or congestion) and skin rash.

Thompson said some men have developed breast cancer after taking finasteride, though it is exceedingly rare.

Casperson said between 2 percent and 10 percent of patients experience some adverse effects. According to the Food and Drug Administration, a four-year controlled clinical study showed up to 8 percent of finasteride users reported erectile dysfunction at the 5-mg dose for BPH.

"Taking a medication is always a discussion of risk versus benefit," Casperson said. "We don't know who will get the side effects, and if the risk of side effects is 5 percent, that means 95 percent of men will not [have any]."

"They are generally considered safe, even for long-term use in small doses, but too much of anything can be bad," Thompson added.

People concerned about finasteride's side effects might consider alternative treatments, including medications such as Flomax, which relaxes the bladder muscles and the prostate; lifestyle changes, such as limiting fluid intake before bed and strengthening the pelvic floor muscles; and surgery, which involves removing part or all of the prostate.