The prostate gland is an internal component of the male reproductive system that sits above the rectum and below the bladder. The urethra (the tube that transports urine from the bladder out through the penis) passes between the prostate’s lobes. In most men, the prostate begins to undergo excessive cell growth sometime around the age of 50. When the prostate begins to grow in the absence of cancer, physicians refer to the condition as benign prostatic hyperplasia, or BPH. While almost all men will have BPH if they live long enough, not everyone experiences symptoms. BPH’s symptoms occur when the prostate’s enlargement causes it to push up against a section of the urethra. Imagine squeezing a drinking straw with your thumb and forefinger. If the straw were the urethra and the fingertips were the prostate’s tissues, you know what would happen…the narrowed urethra would no longer allow urine to pass freely through it. This kind of obstruction can be extremely disruptive to a man’s quality of life. He may feel a too-frequent urge to urinate, he may have trouble peeing when he tries to, he may fail to empty his bladder completely, and he may even experience incontinence or become prone to infections or bladder stones.
These kinds of symptoms prompt many men to seek help from their doctors. One of the first questions often asked is, “Isn’t there a pill I can take to fix this?” The answer is that doctors do prescribe medications for BPH, usually as a first step in addressing the problem. Unfortunately, the drugs available today aren’t a magic bullet. Not all men get relief from them. Some see improvements in their symptoms for a while, only to have the prostate’s continued growth render them insufficient. Some men try the drugs and then stop taking them because they find the side effects unacceptable, while others decline the drugs outright when they learn about the effect they may have on their sex lives.
Whether to take these medications, and which ones to try, is a very personal decision that you should make in consultation with your doctor. You’ll have to take into account how troublesome your symptoms are, how likely a drug is to help you, how well you will tolerate the medication, how important an active sex life is to you at this point in your life, and whether the risk-versus-reward profile of a procedure or surgery looks better in comparison.
These two medications, both of them daily pills, belong to a family of drugs called 5-alpha reductase inhibitors. They work to slow or reverse the growth of the prostate. Here’s how.
While the causes of BPH aren’t completely understood, we do know that prostate cell growth is driven by a hormone called dihydrotestosterone (or DHT). DHT is derived from testosterone, meaning that a certain portion of a man’s testosterone gets converted into DHT. The key to this conversion is an enzyme called 5-alpha reductase. So as the name suggests, a 5-alpha reductase inhibitor medication hampers production of the enzyme that allows the prostate to convert testosterone into DHT to fuel the gland’s overgrowth.
Both of these medications have been proven to significantly reduce production of 5-alpha reductase. Finasteride appears to decrease levels of the enzyme by 70%, and dutasteride cuts production by 93%. But how do those figures for 5-alpha-reductase inhibitors translate into actual prostate shrinkage? Finasteride appears to decrease prostate size by 18%, while dutasteride shrinks it by about 25%. For many men, that level of reduction takes enough pressure off the urethra to provide relief of urinary symptoms.
However, these drugs have drawbacks that make them unacceptable for some men. For one thing, their positive effects take a while to kick in, sometimes as long as six months. For another thing, they’re not a permanent solution to BPH. When men stop taking these drugs, their symptoms come back. And the drugs frequently have side effects that make a lot of men decline or discontinue them.
When some men take 5-alpha reductase inhibitors, they see a steep diminishment in their sex drives. Some find themselves newly unable to get or keep an erection, and some struggle to ejaculate when they orgasm. Sometimes people taking these drugs become depressed or anxious. Some men experience swelling of their breast tissue, a condition known as gynecomastia. And finally, studies have shown an association between 5-alpha-reductase inhibitors and increased risk of prostate cancer.
While the 5-alpha reductase inhibitor medications relieve BPH symptoms by shrinking the prostate, drugs from a different class known as alpha blockers achieve symptom relief by helping the muscles in the urinary tract to relax.
What are alpha blockers? They’re medications that disrupt the signaling that certain cells in the body receive via substances called neurotransmitters, which are generated by the nervous system. The cells of some parts of our bodies have features called adrenergic receptors which, when reached by neurotransmitters, convert the neurotransmitters’ signals into instructions to constrict or squeeze. Perhaps because “adrenergic” is a slightly awkward term, adrenergic receptors are more commonly referred to as alpha receptors. The urinary tract, including the prostate, contains these “alpha” adrenergic receptors, specifically a type called alpha-1 receptors.
What do alpha blockers do? The symptoms of BPH aren’t just caused by the prostate merely sitting idly up against the urethra but rather by it constricting around it. The alpha adrenergic blockers prescribed for BPH work by attaching to the alpha-1 receptors to block neurotransmitters from telling the prostate and bladder neck to grip at the urethra. The result is a smoother passage of urine through the urinary tract, making it easier to live with an enlarged prostate.
Which alpha blockers are prescribed for BPH? The subclass known as “selective alpha-1 blockers” are the alpha-blocker medications used to treat enlarged prostate. They include terazosin, silodosin, alfuzosin, tamsulosin, and doxazosin.
How well do they work..? A 2024 Nature Scientific Reports review of previously published studies found that all five of the alpha blockers approved for BPH significantly improve recipients’ International Prostate Symptom Scores (IPSS). However, there were differences in the relative effectiveness of some of the alpha blockers compared to others. The most effective of the group appeared to be tamsulosin, at 89%, and the least effective was doxazosin at 22%. Note, however, that this finding runs directly counter to a 2013 review that found doxazosin to be the most effective at relieving symptoms. The 2024 study also looked at the impact of alpha blockers on quality of life and found that none of the medications had a statistically significant positive impact. Most men taking an alpha blocker will need additional treatment, possibly including a 5-alpha reductase inhibitor. Unfortunately, taking two drugs could possibly double the side effects, which in the case of alpha blockers can include difficulty ejaculating, fatigue, lightheadedness, and dizziness. Unlike 5-alpha reductase inhibitors, alpha blockers kick in right away.
