What causes an enlarged prostate? Mostly aging, plus the hormone DHT, which keeps prostate cells growing for decades. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) says scientists still are not sure exactly why it happens. The condition, called benign prostatic hyperplasia or BPH, affects 29 to 33 percent of men 65 and older.
Quick answer: An enlarged prostate comes from age-related growth driven by DHT, a hormone made from testosterone. Family history, obesity, diabetes and inactivity raise the odds. Early signs are a weak stream and getting up at night to pee. BPH is not cancer. It is managed rather than cured, and saw palmetto did no better than placebo in a 2023 Cochrane review.
What causes an enlarged prostate?
The prostate is a walnut-sized gland that sits under the bladder and wraps around the urethra, the tube urine leaves through. It grows at puberty, then starts growing again for many men somewhere in midlife. Because it surrounds the urethra, even modest growth can squeeze the flow of urine. That is the whole problem in one sentence.
The main driver is hormonal. According to the StatPearls review of benign prostatic hyperplasia, an enzyme called 5-alpha reductase turns testosterone into dihydrotestosterone (DHT) inside the prostate, and DHT tells prostate cells to multiply. The clearest proof is an odd one: men castrated before puberty do not develop BPH. Yet the same review notes there is no clear relationship between blood levels of testosterone or DHT and how bad symptoms get. It is the local hormone signal inside the gland that matters, not the number on a lab report.
Age is the other half. StatPearls cites autopsy studies finding BPH tissue in 50 to 60 percent of men in their 60s and 80 to 90 percent of men over 70. Symptoms track with age too: NIDDK puts BPH at 5 to 6 percent of men aged 40 to 64, rising to 29 to 33 percent of men 65 and older.
Then there are risk factors, some fixable and some not. The NIDDK’s BPH page lists:
- Age 40 or older
- Family history of BPH (StatPearls cites one study finding a fourfold higher risk in first-degree relatives)
- Obesity
- Type 2 diabetes
- Heart and blood vessel disease
- Chronic kidney disease
- Erectile dysfunction
- Not being physically active
Look at how much of that list overlaps with metabolic health. StatPearls describes a meta-analysis linking metabolic syndrome to larger prostates, and observational studies tying obesity to higher risk, while saying plainly that causation is not established. Low-grade inflammation in the gland shows up often under the microscope as well. Our view is that the prostate does not get enlarged in isolation from the rest of a man’s body, even if nobody can yet say exactly how much weight, blood sugar and inflammation add.
NIDDK says no proven way to prevent BPH has been found, and that diet has not been shown to cause or prevent it. Being physically active may lower the risk. That is a modest claim. We would rather give you the modest version.
What are the first signs of prostate problems?
For BPH, the early signs are about flow and timing. NIDDK lists:
- Trouble starting to urinate, or straining
- A weak or stop-and-start stream
- Dribbling after you finish
- Feeling like the bladder has not fully emptied
- Getting up at night to urinate (nocturia)
- Urgency and frequency during the day
- Pain with urination
Most men notice the nighttime trips first. Once is common. Two or three times a night, every night, is worth a visit.
Symptom severity does not always match prostate size. NIDDK notes that some men with a very large gland have few symptoms and some with a slightly enlarged one have a lot. Some medicines can make things worse, too: over-the-counter cold and allergy medicines with decongestants or antihistamines, some antidepressants, tranquilizers and diuretics. If your stream got worse the week you started a cold medicine, that is probably not a coincidence.
Here is the part men tend to get backwards. Those same urinary symptoms can come from BPH, prostatitis or, less often, prostate cancer, which is why they need a checkup rather than a guess. But early prostate cancer usually causes no symptoms at all. The CDC says most prostate cancers do not cause symptoms early on. A normal stream does not rule cancer out, and a weak stream does not mean you have it. BPH does not turn into cancer, though both are common at the same ages and a man can have both.
Screening is its own decision. We cover PSA testing and prostate cancer risk, including what can push a PSA reading up, in a separate post.
Some symptoms should not wait for a routine appointment. NIDDK says to get care right away if you cannot urinate at all, if painful, frequent urination comes with fever and chills, if there is blood in your urine, or if you have severe pain in the lower belly or urinary tract.
Does an enlarged prostate cause frequent urination?
Yes. NIDDK lists urgency and frequency right alongside a weak stream and trouble emptying the bladder, and the two are connected. When the enlarged gland narrows the urethra, the bladder may not empty completely each time. A bladder that is still partly full fills back up to the urge point sooner. So BPH can give you the odd combination of a slow stream and a frequent, sudden need to go.
Frequent urination is not proof of BPH, though, and other causes need ruling out. That is part of why the standard workup NIDDK describes starts with a history and a urine test before anything else, and may add a digital rectal exam, a PSA blood test and sometimes a bladder flow test or ultrasound.
Some of NIDDK’s practical advice for frequency is simple enough to start this week:
- Drink less in the two hours or so before bed and before long drives
- Cut back on alcohol and caffeine
- Empty your bladder fully, and do not hold urine for long periods
- Stay physically active
- Review medicines that make symptoms worse with your clinician
The “two hours” is our rule of thumb, not a number from NIDDK. Try it for a couple of weeks and count the night trips.
Does an enlarged prostate cause ED?
The two are tightly linked, though whether one causes the other is still debated. NIDDK lists erectile dysfunction as a risk factor for BPH. The biggest data set on the connection is the Multinational Survey of the Aging Male (MSAM-7), published in European Urology in 2003. It analyzed 12,815 men aged 50 to 80 in the US and six European countries and found that sexual problems rose with both age and the severity of urinary symptoms. After adjusting for diabetes, high blood pressure, heart disease and high cholesterol, urinary symptoms were still an independent risk factor for sexual dysfunction.
Our read is that shared risk factors explain a lot of it. Compare the lists: age, diabetes, obesity, heart disease and inactivity raise the odds of both. The MSAM-7 adjustment suggests that is not the whole story, though, and what is left over has not been explained.
Treatment matters here too. StatPearls notes that alpha blockers, a common BPH medicine, often cause ejaculation problems, and NIDDK lists erectile dysfunction and retrograde ejaculation (semen going back into the bladder) among the possible complications of BPH surgery. On the other side, NIDDK lists PDE-5 inhibitors, the drug class used for ED, among the medicines that can relieve some BPH symptoms. If sex matters to you, say so before any BPH treatment is chosen. It changes the options.
If you have noticed a new curve or lump rather than weaker erections, read our post on what Peyronie’s disease is.
Can an enlarged prostate be cured?
Usually not in the sense of making it go away for good. It can be managed well, and many men never need more than lifestyle changes and periodic checkups. NIDDK is direct about it: even surgery that removes part of the prostate “may not cure BPH,” although it can relieve symptoms, and about 10 percent of men who have surgery may need more surgery within 20 years.
Not every man needs treatment. For mild symptoms that do not bother you, NIDDK describes watchful waiting with a yearly checkup. Left alone, BPH does progress in some men. StatPearls cites an observational group in which 31 percent of untreated men needed further treatment and 5 percent developed acute urinary retention, an inability to urinate, over 48 months. Larger glands, over about 30 grams, carry more risk of progressing.
| Approach | What it does | What to know |
|---|---|---|
| Watchful waiting and habit changes | Less evening fluid, less alcohol and caffeine, staying active | NIDDK’s first step for mild symptoms, with a yearly checkup |
| Alpha blockers | Relax muscle at the bladder neck and in the prostate | Ease symptoms but do not shrink the gland; ejaculation problems are common |
| 5-alpha reductase inhibitors | Block DHT production | Shrink the prostate up to 25 percent over about six months and cut PSA about in half |
| Minimally invasive procedures | Water vapor therapy or small implants that hold tissue back | Done by a urologist; some report preserved sexual function |
| Surgery | Removes obstructing tissue | For severe symptoms or complications; about 10 percent need more surgery within 20 years |
| Saw palmetto | Plant extract sold for prostate health | No better than placebo in a Cochrane review of 27 trials |
The PSA point trips people up. On a 5-alpha reductase inhibitor, StatPearls says PSA can fall by about 50 percent, so whoever reads yours needs to know. The choice among these belongs with your prescriber or urologist.
Does saw palmetto shrink the prostate?
No good trial has shown that it does, and it does not relieve symptoms better than a sugar pill either. Saw palmetto is on every pharmacy shelf with a prostate label, so the evidence is worth laying out.
The 2023 Cochrane review by Franco and colleagues pooled 27 studies of 4,656 men. On its own, saw palmetto performed no better than placebo. At 3 to 6 months, symptom scores were 0.9 points better on a 35-point scale, a difference men would not notice. At 12 to 17 months, there was no difference at all. The authors rated that evidence high certainty and concluded saw palmetto “provides little to no benefits” for urinary symptoms from an enlarged prostate. Side effects were about the same as placebo.
Harvard Health walks through the two big American trials. In one, 225 men with moderate to severe BPH took 160 mg twice a day or placebo for a year, with no difference. Critics said the dose was too low, so a second trial led by Dr. Michael Barry gave nearly 370 men up to 320 mg three times a day for about a year and a half. Still no difference. About 40 percent of the placebo group reported feeling better, which tells you how easy it is to believe a supplement is working. Harvard also notes no herbal supplement is FDA-approved for BPH, and that saw palmetto may affect blood clotting, so it is a concern for men on blood thinners.
As a naturopathic clinic, we use botanical medicine. We still would not spend money on saw palmetto for prostate symptoms. Harvard-affiliated urologist Dr. Heidi Rayala put it fairly: it “is unlikely to harm you, but it probably won’t provide any major benefits either.”
Myth: An enlarged prostate means you are more likely to get prostate cancer.
Fact: BPH is benign and does not turn into cancer. Both are common in older men, so you can have both, but one does not cause the other.
Myth: Saw palmetto shrinks the prostate.
Fact: A 2023 Cochrane review of 27 trials and 4,656 men found little to no benefit over placebo, and a trial using triple the usual dose found no difference either.
Myth: A bigger prostate always means worse symptoms.
Fact: NIDDK notes that symptoms do not always match size. Some men with large glands have few problems, and some with small ones have many.
Frequently asked questions
At what age does the prostate start to enlarge?
The prostate has a second growth phase that starts for many men in midlife. NIDDK says BPH rarely causes symptoms before 40, affects 5 to 6 percent of men aged 40 to 64, and 29 to 33 percent of men 65 and older. Autopsy studies cited by StatPearls find BPH tissue in 50 to 60 percent of men in their 60s and 80 to 90 percent past 70, though many never notice it.
Can high testosterone cause an enlarged prostate?
Not in a simple way. The prostate needs DHT, which is made from testosterone, to grow, and men castrated before puberty do not develop BPH. But StatPearls notes no clear relationship between blood testosterone or DHT levels and symptomatic BPH. Men on testosterone therapy should still have prostate symptoms and PSA monitored, since an enlarged prostate can raise PSA.
Can you shrink an enlarged prostate naturally?
There is no proven natural way to shrink it. NIDDK says diet has not been found to cause or prevent BPH, and saw palmetto failed in a Cochrane review of 27 trials. Habits can ease symptoms, though: less fluid before bed, less alcohol and caffeine, staying active and fully emptying your bladder. The medicines shown to shrink the gland are 5-alpha reductase inhibitors.
Is an enlarged prostate dangerous?
Usually not, but it can be. NIDDK lists complications including being unable to urinate, urinary tract infections, bladder stones, blood in the urine and kidney damage. Get care right away if you cannot urinate, have painful urination with fever and chills, see blood in your urine or have severe lower belly pain. Otherwise, mild symptoms can be watched with yearly checkups.
Does an enlarged prostate always need treatment?
No. For mild symptoms that do not bother you, NIDDK describes watchful waiting: habit changes plus a checkup about once a year. Treatment makes more sense when symptoms disrupt sleep or daily life, or when complications such as retention, infections or bladder stones appear. StatPearls notes that larger glands, over about 30 grams, are more likely to progress, which is one reason a baseline exam helps.
If you are up at night more than you used to be, or your stream has slowed, a checkup is the right first move, partly to rule out the things that are not BPH. Dr. Drew Collins at Proactive Choice can go over your symptoms, labs and the metabolic risk factors that travel with an enlarged prostate, and refer to a urologist when that is the right call. You can read more about our men’s health clinic in Bend, or book a free 15-minute call at +1 (858) 333-5196.
Sources
- National Institute of Diabetes and Digestive and Kidney Diseases. Enlarged Prostate (Benign Prostatic Hyperplasia).
- Ng M, Leslie SW, Baradhi KM. Benign Prostatic Hyperplasia. StatPearls, NCBI Bookshelf, updated 2024.
- Franco JVA, et al. Serenoa repens (saw palmetto) for lower urinary tract symptoms in men with benign prostatic enlargement. Cochrane Database of Systematic Reviews, 2023.
- Harvard Health Publishing. Can saw palmetto treat an enlarged prostate?
- Rosen R, et al. Lower urinary tract symptoms and male sexual dysfunction: the Multinational Survey of the Aging Male (MSAM-7). European Urology, 2003.
- Centers for Disease Control and Prevention. Symptoms of Prostate Cancer.
Medically reviewed content from Proactive Choice. This article is for education and is not a diagnosis. Talk with a licensed clinician about your own symptoms and treatment options.
Want to talk this through for your own health? Book a visit with Dr. Drew Collins, ND at 601 NW Harmon Blvd in Bend, or call (858) 333-5196.
