Anticholinergics and Urinary Retention: How Prostate Problems Make It Riskier

If you're a man over 60 with an enlarged prostate, and your doctor just prescribed a pill for an overactive bladder, stop for a second. That medication might be doing more harm than good.

What Anticholinergics Do to Your Bladder

Anticholinergics like oxybutynin, solifenacin, and tolterodine are meant to calm an overactive bladder. They work by blocking a chemical called acetylcholine that tells the bladder muscle to squeeze. For someone with no prostate issues, this can mean fewer bathroom trips and less urgency. But for men with benign prostatic hyperplasia (BPH), it’s like turning down the engine on a car already stuck in mud.

The bladder in men with BPH is already working overtime. The prostate squeezes the urethra shut, so the bladder has to push harder to get urine out. That’s why many of these men have weak urine flow, straining, or a feeling that they haven’t fully emptied. Now add an anticholinergic on top of that. It weakens the bladder’s squeeze even more. The result? Urine builds up. And if it builds up enough, you can’t pee at all.

Why This Is a Silent Emergency

Urinary retention isn’t just uncomfortable. It’s dangerous. Acute urinary retention means your bladder fills up so much that you can’t pass any urine-even if you try for hours. This isn’t rare. Studies show that up to 10% of all urinary retention cases are caused by medications, and anticholinergics are the top offenders.

Men with BPH who take these drugs have a 2.3 times higher risk of sudden retention than those who don’t. The numbers don’t lie: between 2018 and 2022, over 1,200 cases of urinary retention linked to anticholinergics were reported to the FDA. Nearly two-thirds of those cases happened in men over 65 with diagnosed prostate enlargement.

One man on a prostate support forum described it this way: “I started Detrol for urgency. Three days later, I couldn’t pee. My bladder was stretched to 1,200 ml-more than a full soda bottle. I ended up in the ER with a catheter.” That’s not an outlier. Reddit threads from men with BPH show 78% had bad experiences with anticholinergics. Over a third ended up needing a catheter.

Doctors Know This. So Why Is It Still Happening?

The American Urological Association has been clear since 2018: don’t give anticholinergics to men with moderate to severe BPH. Their guidelines say avoid them if your prostate is over 30 grams or your symptom score is above 20. The American Geriatrics Society calls these drugs “potentially inappropriate” for older men with urinary retention.

Yet, a 2019 study found that 40% of nursing home residents with BPH were still being prescribed anticholinergics. Why? Because doctors sometimes focus only on the urgency, not the obstruction. They see frequent bathroom trips and think, “Let’s quiet the bladder.” They forget that the bladder isn’t overactive-it’s struggling.

There’s also a gap in patient education. Many men don’t know that their prostate is part of the problem. They take the pill because it’s “for bladder control,” and don’t realize it could lock their bladder shut.

What Are the Safer Alternatives?

If you have BPH and overactive bladder symptoms, you have better options.

• Alpha-blockers like tamsulosin (Flomax) or alfuzosin (Uroxatral) relax the muscles around the prostate and urethra. They don’t weaken the bladder-they help it work better. Studies show men on alpha-blockers after catheter removal are 30-50% more likely to pee on their own within a few days.
• 5-alpha reductase inhibitors like finasteride (Proscar) or dutasteride (Avodart) shrink the prostate over time. After four to six years, they cut the risk of acute retention by half.
• Mirabegron (Myrbetriq) and vibegron (Gemtesa) are newer drugs that work differently. Instead of blocking nerves, they stimulate a different receptor in the bladder to relax it. In trials, mirabegron caused urinary retention in only 4% of men with mild BPH-compared to 18% with anticholinergics.

The FDA approved vibegron in 2020 specifically for men who can’t tolerate anticholinergics. It’s not a magic bullet, but it’s a much safer bet for prostate patients.

When Might Anticholinergics Still Be Used?

There’s one small group where they might still be considered: men with very mild BPH and clear signs of detrusor overactivity (a bladder that contracts too hard, too often). A 2017 study found that if you screen carefully-check your urine flow, measure residual volume, and start with a low dose-some men can use solifenacin without trouble.

But here’s the catch: even then, you need strict monitoring. Monthly uroflow tests. Regular checks of how much urine is left after you pee. If your peak flow drops below 10 mL/sec or your post-void residual climbs above 150 mL, you need to stop the drug.

Most doctors won’t go down this road unless they’ve ruled out everything else. And even then, they’ll warn you: “If you can’t pee, come right in.”

What You Should Do Right Now

If you’re taking an anticholinergic and have BPH:

1. Don’t stop cold turkey. Talk to your doctor first.
2. Ask for a uroflow test. This measures how fast you pee. A rate below 10 mL/sec means high risk.
3. Get a post-void residual check. A bladder that holds more than 150 mL after urinating is already struggling.
4. Ask if you can switch to mirabegron or vibegron.
5. If you’re already catheterized or had a retention episode, alpha-blockers like tamsulosin should be started immediately.

If you haven’t started the medication yet, ask your doctor: “Is my prostate size or flow rate being checked? Is there a safer option?”

The Bigger Picture

This isn’t just about one drug. It’s about how we treat aging bodies. We often treat symptoms without looking at the whole system. A weak bladder isn’t always overactive-it’s under pressure. A frequent urge isn’t always a nervous bladder-it’s a blocked pipe.

By 2028, experts predict anticholinergic prescriptions for men over 65 with BPH will drop by 35%. Why? Because better options exist. Because the risks are too high. And because more doctors are learning to see the prostate-not just the bladder.

If you’re managing BPH and bladder symptoms, you deserve a plan that doesn’t put you at risk of a hospital visit. Ask the right questions. Demand the right tests. And don’t accept a pill just because it’s been prescribed before.