What BPH is
BPH is a non-cancerous enlargement of the prostate. It is not prostate cancer and does not progress to it, though the two can coexist.
The prostate sits below the bladder and wraps around the urethra, the tube urine passes through. When it enlarges it can squeeze that tube and make urine harder to pass. The bladder muscle then works harder to push against the resistance, and over time that muscle becomes overactive, and can weaken - which is what produces the urgency and the night-time trips.
The symptoms men notice, per the NIDDK, are trouble starting a urine stream or emptying the bladder, a weak or interrupted stream or dribbling at the end, waking at night to urinate, sudden urgency, going frequently, and pain when urinating.
Prostate size tends to be a poor predictor of trouble. A substantially enlarged gland may cause almost none, and a modestly enlarged one may cause a great deal. Treatment decisions follow symptoms, not imaging.
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Why the two conditions overlap
Age: Both become far more common each decade after 50.
Shared vascular biology: Diabetes, high blood pressure, high cholesterol and metabolic syndrome damage blood vessels, and all are established risk factors for erectile dysfunction as well as urinary symptoms. Narrowed pelvic arteries and changes in smooth muscle affect the bladder and prostate the same way they affect erectile tissue.
Sleep: A man waking three times a night is not sleeping properly, and poor sleep independently contributes to sexual difficulty. Part of the link is one condition degrading the conditions the other depends on.
Where tadalafil fits
Tadalafil at 5 mg once daily is FDA-approved to treat the symptoms of an enlarged prostate, and separately approved for men who have both BPH and ED at the same dose.
In the two main trials - on the International Prostate Symptom Score (IPSS) questionnaire - average symptom scores fell 4.8 points on tadalafil against 2.2 on placebo in one study, and 5.6 against 3.6 in the other, from starting scores of roughly 16 to 17 on a 35-point scale. In the trial of men with both conditions, scores fell 6.1 points against 3.8 on placebo.
Improvement showed up at the first point anyone measured, which was week 4 in the prostate-only studies and week 2 in the combined study. It is not an overnight effect.
The mechanism is not fully understood. Researchers believe tadalafil relaxes smooth muscle in the prostate, the bladder and their blood supply, but this has not been formally established.
One limitation worth knowing: if tadalafil is combined with finasteride to start BPH treatment, that combination is recommended for up to 26 weeks; the added benefit falls off between week 4 and week 26, and further studies are needed for beyond that.
The trade-off in prostate treatment
A class of drugs called 5-alpha reductase inhibitors, which includes finasteride and dutasteride, shrinks the prostate and reduces the chance of needing surgery later. They are effective and appropriate for many men. They also carry documented sexual side effects, and that’s the conversation that often does not happen before the prescription is written.
| Medication | Impotence | Reduced libido | Timeframe |
|---|---|---|---|
| Finasteride 5 mg (prostate) | 8.1% vs 3.7% placebo | 6.4% vs 3.4% | Year 1; no significant difference in years 2-4 |
| Finasteride 1 mg (hair loss) | 1.3% vs 0.7% placebo | 1.8% vs 1.3% | Year 1 |
| Dutasteride | 4.7% vs 1.7% placebo | 3.0% vs 1.4% | First 6 months |
Both drugs also carry reports of sexual dysfunction continuing after men stop taking them. These reports are uncommon and it is not established whether the drug is responsible, but the possibility exists and men should hear about it before starting rather than after.
None of this means avoiding these drugs. An untreated blocked prostate has real consequences of its own: it can reach the point where you cannot urinate at all, which is a medical emergency, and prolonged back-pressure can damage the kidneys. The point is that the trade-off belongs to the patient, which requires him being told about it.
Practical points
Get urinary symptoms evaluated rather than assuming they are just age. Infections, bladder problems and cancer produce similar symptoms.
Raise both complaints in the same appointment. A treatment chosen for one can worsen the other, and your doctor can only account for what you have mentioned.
If something changed sexually after starting a prostate medication, say so. Alternatives and different combinations exist.
Takeaways
An enlarged prostate and erectile dysfunction show up together because they share risk factors, share vascular biology, and because broken sleep undermines sexual function. Tadalafil 5 mg once daily is approved for both, lowering symptom scores by 4.8 to 6.1 points against 2.2 to 3.8 on placebo. Separately, finasteride and dutasteride are effective prostate treatments that carry first-year impotence rates of 8.1 and 4.7% against 3.7 and 1.7% on placebo. Mention both problems in the same conversation, because the treatment you get depends on what your doctor knows.
Dr. Chughtai is a Board-Certified urologist and the author of 160+ peer-reviewed publications, with fellowship training at Weill Cornell.
Read full bio →Sources
- CIALIS (tadalafil) tablets, prescribing information. Eli Lilly and Company, via DailyMed.
- Prostate Enlargement (Benign Prostatic Hyperplasia). National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health.
- PROSCAR and PROPECIA (finasteride) prescribing information, via DailyMed.
- AVODART (dutasteride) prescribing information, via DailyMed.
