FAQ  /  Men's Hormone Health

Will Testosterone Make My Enlarged Prostate Worse?

Why men have been told testosterone makes this worse

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The prostate is an androgen-responsive organ. Testosterone and its more potent metabolite dihydrotestosterone are part of normal prostate development and normal prostate biology, and drugs that lower dihydrotestosterone, finasteride and dutasteride, do shrink the gland. From that, a simple chain of reasoning follows: more testosterone means more prostate growth, which means worse symptoms.

The human evidence has turned out to be considerably more interesting than that. Needing androgen to grow is not the same thing as growing in proportion to however much androgen is available. A tissue can require a hormone and still be indifferent to receiving more of it once it has enough, and that appears to be what the prostate does.

The saturation idea, in plain terms

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Androgens act on prostate cells through the androgen receptor, and each cell has only so many receptors to act on. Clinical data suggest those receptors are already substantially occupied at fairly low androgen concentrations, with the point of saturation sitting near a total testosterone of about 250 ng/dL. Below that, changes in testosterone matter to prostate tissue. Above it, adding more testosterone has much less left to do through that pathway.

Think of the receptors as seats in a small theater. Going from very little testosterone to an adequate amount fills seats that were empty. Once nearly every seat is taken, gathering a larger crowd outside does not create more seats.

This is a model rather than proof, and it is worth saying so. A 2020 review argued that much of the evidence originally assembled to support it came from experiments designed to answer other questions, and the model's authors replied that recognizing saturation in existing data was the point. Its usefulness is that it offers a coherent reason why the steady increase in prostate trouble that clinicians once expected from testosterone has not turned up in the trials.

What the randomized trials found

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This is the part that should carry the most weight, because these studies compare men given testosterone against men given placebo, with the assignment made by chance.

Urinary symptoms in these trials are measured with the International Prostate Symptom Score, a standard questionnaire that adds up the things men actually notice: a weak stream, trouble getting started, having to go frequently, urgency, stopping and starting, a sense of not emptying completely, and how many times a night you are getting up. It runs from 0 to 35, with roughly 0 to 7 counted as mild, 8 to 19 moderate, and 20 and above severe.

The most direct analysis pooled 14 placebo-controlled trials covering 2,029 men, average age 64.5, followed an average of 34 months. Symptom score changed by minus 0.41 points in the men on testosterone and plus 0.12 in the men on placebo. In other words testosterone drifted very slightly toward improvement and placebo very slightly toward worsening, neither change was statistically significant, the difference between the groups was not significant either, and the individual trials agreed with each other rather than scattering. On a 35-point scale, four tenths of a point is not something a man would feel.

Two larger analyses reached the same place. One pooled 28 randomized trials and 3,461 men, eleven of those trials running a year or longer, and found no effect of testosterone on symptom score, peak urinary flow rate, post-void residual volume, or prostate volume. Another pooled 21 randomized trials and 2,453 men and found no difference across transdermal, intramuscular, or oral testosterone.

TRAVERSE supplies the largest single dataset. Among 5,246 men treated for about two years, urinary symptom scores did not differ from placebo, and neither did acute urinary retention, prostate surgery for benign disease, or new prescriptions for urinary symptoms. Those events were uncommon in both groups.

Prostate size and urinary symptoms are not the same thing

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This distinction does more work than almost anything else on this page. Men tend to assume a bigger prostate automatically means a harder time urinating, and the relationship is much looser than that. Symptoms depend on bladder muscle function, smooth muscle tone in the prostate and urethra, inflammation, metabolic health, sleep, medications, fluid habits, and aging, not on gland size alone. Plenty of men with large prostates have modest symptoms, and plenty with modest enlargement are miserable.

Which means the question worth answering is not only whether testosterone changes prostate volume. It is whether testosterone makes men urinate worse. On that question the evidence is reassuring, and on the volume question it is close to neutral with one honest wrinkle.

Randomized trials running one to three years find no measurable change in prostate volume. A Swedish cohort that followed 511 men across 3,745 visits, comparing each man's treated periods against his own untreated periods, did find prostate growth running about 0.22 mL per year faster during treatment. That reached statistical significance, and it came with no accompanying change in urinary symptoms, quality of life, or PSA. A twelve-year cohort likewise saw prostate volume rise while symptoms and post-void residual volume improved. The sensible reading is that a man restored to normal androgen levels grows a prostate at closer to a normal rate, which over years amounts to a clinically silent difference, and that whatever is happening to symptoms is being driven by something other than size.

What about DHT?

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Men often arrive having heard that dihydrotestosterone is what enlarges the prostate, and that testosterone therapy raises it. Dihydrotestosterone genuinely is central to prostate biology. What does not follow is that a higher circulating level translates step for step into a larger prostate or a worse stream.

That was tested directly in a large analysis of the REDUCE trial population, covering 3,009 men with no urinary symptoms and 2,145 men who already had them. Neither serum testosterone nor serum dihydrotestosterone, examined by quintile from lowest to highest, predicted who went on to develop urinary symptoms or whose existing symptoms progressed. The result held in both arms of that trial. Higher androgen levels simply did not identify the men who did worse.

On the related question of whether one delivery route is gentler on the prostate than another, the pooled comparison across transdermal, intramuscular, and oral testosterone found no difference in symptom score, prostate volume, or PSA. There is no good evidence to prefer one route over another for prostate reasons.

Some studies report improvement, which is worth knowing without overselling

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Several studies have found urinary symptoms stable or better after testosterone replacement rather than worse, and that is worth knowing precisely because it corrects the assumption that decline is inevitable.

The most interesting of these followed 321 hypogonadal men on testosterone undecanoate for twelve years. Symptom score and post-void residual volume both improved. What makes it more than a before-and-after observation is that treatment was interrupted in 147 of those men for an average of about seventeen months. During the interruption symptoms and residual volume significantly worsened, and both recovered when treatment resumed. Losing a benefit on withdrawal and regaining it on rechallenge is harder to explain away than a simple improvement over time. The pooled analysis of 21 randomized trials also found a significant reduction in symptom score in its long-term intramuscular subgroup.

Held against that, a five-year controlled study in obese hypogonadal men with metabolic syndrome, comparing treated men against matched untreated men, found no change in symptom score, flow rate, residual volume, or prostate size in either group. And the long-term studies reporting improvement were not blinded, which matters here because a symptom score is a subjective questionnaire and every man filling it out knew whether he was being treated.

Researchers have proposed a mechanism that fits the pattern, and it is not a prostate mechanism. Testosterone deficiency travels with obesity, metabolic syndrome, inflammation, oxidative stress, vascular dysfunction, and disrupted sleep, all of which independently make urinary symptoms worse. A recent review argues that deficiency contributes to urinary symptoms through these systemic routes rather than through the anatomy of the gland, which would explain how symptoms improve in men whose prostates are still slowly enlarging. That territory is covered in more depth in the discussion of redox biology.

The honest conclusion is the modest one. Testosterone should not be described as a treatment for benign prostatic hyperplasia and should not be started for that purpose. What the evidence supports is that having mild or moderate urinary symptoms is not a reason to expect testosterone to make them worse, and that some men find they get somewhat better.

The one group that needs evaluation first

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Men who already have severe urinary symptoms, meaning roughly a symptom score above 19, or who have significant obstruction or retention, are a genuine exception, and the reason is worth understanding because it is not what most men assume.

That group was routinely excluded from testosterone trials in the first place, out of caution about the prostate. TRAVERSE excluded men with severe symptoms and entered men at an average score of 7.1. So the honest statement is that we have much less high-quality evidence about testosterone in men with severe obstruction, not that testosterone has been shown to harm them. Absence of study is not the same as evidence of harm, and the two get conflated constantly in this conversation.

Professional guidance reflects that gap rather than a demonstrated danger. The 2018 Endocrine Society clinical practice guideline recommends against starting testosterone therapy in men with severe lower urinary tract symptoms, among several other conditions warranting evaluation first. Read it for what it says: the threshold is severe symptoms, not the presence of an enlarged prostate. Benign prostatic hyperplasia is extremely common with age and is not by itself a reason to rule out testosterone therapy. A man with severe obstruction should have that evaluated and, where appropriate, treated, and testosterone can reasonably be revisited afterward.

An enlarged prostate is not prostate cancer

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These two get blurred together, and separating them removes a lot of unnecessary worry. Benign prostatic hyperplasia is a non-cancerous enlargement of the gland and is close to universal with age. Having it does not mean a man has prostate cancer or is on his way to it. They are different processes that happen to occur in the same organ in the same decades of life.

PSA and a prostate exam are part of starting and monitoring testosterone therapy, and it helps to understand why. The Endocrine Society guideline advises further urological evaluation before starting when PSA is above 4 ng/mL, or above 3 ng/mL in men at higher risk of prostate cancer, and recommends assessing prostate cancer risk during the first year of treatment. That is ordinary men's health care layered onto a treatment plan, done because prostate cancer is common in this age group and worth catching early, not because testosterone has been shown to cause either enlargement or cancer. What testosterone therapy has been shown to do to PSA is raise it slightly, mostly in the first year and mostly in men who started most deficient, which is exactly why having a baseline before starting is what makes the later numbers interpretable.

What to tell your clinician

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None of the above means urinary symptoms should be ignored on treatment. Tell whoever is managing your care if your stream becomes substantially weaker, if starting becomes noticeably harder, if you stop emptying your bladder properly, if you cannot pass urine at all, if you see blood in your urine, or if your symptoms change quickly rather than gradually.

Those are all worth evaluating in any man of this age, on testosterone or not, and most of them have explanations that have nothing to do with hormone therapy. Saying so is not a warning about testosterone. It is the same reason a new symptom of any kind is worth mentioning rather than waiting out.

Dr. Darrell Wilcox · @wellnessdoc_4everyoung on Instagram

This content is for educational purposes only and does not constitute medical advice, diagnosis, or treatment. Testosterone is a prescription treatment with its own indications, contraindications, and monitoring requirements, and urinary symptoms have many possible causes that deserve proper evaluation. Decisions about starting or continuing testosterone therapy, and about evaluating an enlarged prostate or obstructive symptoms, should be made with your own physician and, where appropriate, a urologist who has your symptom history, exam, and PSA in front of them. Individual results differ from trial averages, and the studies described here were conducted in specific populations that may not match your own situation. Dr. Wilcox is licensed to practice in multiple states. See About for current licensure.