One of the most frustrating symptoms men experience as they get older is having to get up multiple times at night to pass urine. Many men also notice urgency during the day, a slow stream, or the feeling that the bladder never quite empties.

These symptoms are very commonly related to benign prostatic hyperplasia (BPH) — an enlarged prostate.

In this newsletter, I want to explain one specific group of medications that may be recommended for some men: 5-alpha reductase inhibitors. These medications can actually shrink the prostate over time and may improve urinary symptoms for the right patients.

As men age, prostate cells gradually multiply, particularly in the central part of the prostate that surrounds the urethra (the tube urine flows through). As this area enlarges, it compresses the urethra and makes it harder for urine to pass.

This can lead to:

Over time, the bladder has to work harder to push urine past the prostate. This can make the bladder thicker and less elastic, which worsens urgency and frequency symptoms.

Testosterone, the main male hormone, is converted in the prostate into a more active form called DHT (dihydrotestosterone). DHT plays a key role in prostate growth.

5-alpha reductase inhibitors block this conversion, which can:

Common examples include:

Both medications work in a very similar way and are widely used in Australia and internationally.

These medications are not for everyone, but they tend to work best for men who:

Research shows that men with larger prostates do better when a 5-alpha reductase inhibitor is combined with an alpha-blocker (a medication that relaxes the prostate muscle to improve flow).

In Australia, there is a combination tablet available on the PBS, which makes this approach affordable and convenient for many men.

These medications work slowly — they are not a quick fix.

Over 6 months or more, men can expect:

Studies show that these medications can reduce the risk of urinary retention by about 50%, although the absolute risk reduction is modest.

If you take a 5-alpha reductase inhibitor for more than 6 months:

This is very important for prostate cancer monitoring. Always make sure your doctor knows you are taking this medication when interpreting PSA results.

Like all medications, 5-alpha reductase inhibitors can have side effects. The most important to be aware of are:

Because of these potential effects, I generally do not prescribe these medications to younger, sexually active men. They are best suited to older men, particularly those who are no longer sexually active or for whom sexual side effects are not a concern.

Not necessarily.

Some men prefer:

Choosing the right treatment depends on:

This is why an individualised discussion with your urologist is so important.

A 5-alpha reductase inhibitor may be suitable if:

As always, treatment should be tailored to you, not just your prostate size or test results.