Benign Prostatic Hyperplasia: Which Drug Works in Days, Which Takes Months and Why
The prostate sits directly beneath the bladder with the urethra running through the middle of it. When it enlarges, it squeezes that channel, and the bladder has to generate more pressure to empty. Over years the bladder muscle thickens and becomes irritable, which is why the symptoms split into two groups that feel unrelated: a weak hesitant stream on one hand, urgency and night-time trips on the other.
The practical consequence runs through the whole of treatment. Prostate size and symptom severity correlate poorly. A man with a modestly enlarged gland and an irritable bladder can be far more troubled than one with a very large prostate and a compliant bladder. That is why treatment is chosen on symptoms and prostate size together, not on size alone.
⏱️ The one thing worth knowing before anything else: the two main drug classes work on completely different timescales.
Alpha-blockers relax muscle and work within days to two weeks. They do not change the size of the prostate.
5-alpha reductase inhibitors shrink the prostate and take three to six months, with full effect at six to twelve. They do nothing in the first weeks.
Almost every complaint that a prostate tablet is not working comes from expecting the second timescale to behave like the first.
🚻 Scoring the symptoms, because the score decides the treatment
Symptoms are quantified with the International Prostate Symptom Score, seven questions scored 0 to 5, giving a total out of 35, plus a separate quality-of-life question.
| Score | Severity | Usual approach |
|---|---|---|
| 0 to 7 | Mild | Watchful waiting with lifestyle measures and annual review |
| 8 to 19 | Moderate | Medication, usually starting with an alpha-blocker |
| 20 to 35 | Severe | Medication, often combination, with surgical options discussed |
It is worth completing the score before treatment and again after three months, because it converts a vague sense of improvement into a number. A drop of three points or more is generally considered clinically meaningful.
Assessment otherwise includes urinalysis to exclude infection and blood, a digital rectal examination, PSA, measurement of post-void residual urine by ultrasound, and prostate volume where a 5-alpha reductase inhibitor is being considered, because that drug only works properly in larger glands.
🚨 What needs attention now rather than later
🚑 Same-day assessment for any of these.
- Unable to pass urine at all, with a painful distended lower abdomen — acute retention, needing a catheter
- Fever with flank or perineal pain, shivering — possible prostatitis or kidney infection
- Visible blood in the urine, particularly with clots
- Confusion or drowsiness with reduced urine output — possible kidney impairment from chronic retention
- Repeated urinary infections, which in a man are never considered uncomplicated
Chronic retention can be painless. A gradually enlarging lower abdomen, dribbling incontinence and rising creatinine can develop without the man ever feeling unable to pass urine, which is why post-void residual is measured rather than assumed.
💊 The classes, with the drugs and the doses
🔹 Alpha-blockers: fast relief
These relax the smooth muscle of the prostate and bladder neck, widening the channel without changing the gland. They improve the symptom score by 4 to 6 points and they are the usual first choice for anyone whose main complaint is symptoms rather than size.
| Drug | Dose | Notes |
|---|---|---|
| Flomax (Tamsulosin 0.4 mg) | 0.4 mg once daily, 30 minutes after the same meal each day | Prostate-selective, so less effect on blood pressure. No titration needed |
| Hytrin (Terazosin) | 1 mg at bedtime, doubled weekly towards 5 to 10 mg | Also lowers blood pressure, which can be an advantage if hypertension coexists. Needs careful titration |
| Cardura (Doxazosin) | 1 mg at bedtime, titrated upward | Similar profile to terazosin |
⚠️ Three things to know about alpha-blockers.
1. Ejaculation changes. Tamsulosin commonly causes reduced or absent ejaculate, because the bladder neck no longer closes. It is harmless and reversible on stopping, and it is distressing if nobody mentions it beforehand. This is the commonest reason men stop the drug.
2. The first-dose effect. Terazosin and doxazosin can cause dizziness or fainting on standing after the first dose, which is why they are started at 1 mg at bedtime and increased slowly. Tamsulosin carries much less of this.
3. Tell the eye surgeon. Alpha-blockers cause intraoperative floppy iris syndrome, which complicates cataract surgery if the surgeon is not expecting it. Anyone who has ever taken one, even in the past, should say so before cataract surgery — stopping the drug shortly before does not reliably prevent it, so the surgeon needs to know rather than the drug needing to stop.
🔹 5-alpha reductase inhibitors: shrinking the gland
These block the conversion of testosterone to dihydrotestosterone, the hormone that drives prostate growth. The gland shrinks by roughly 20 to 25 percent over six months, and crucially they are the only drugs shown to reduce the long-term risk of acute retention and of needing surgery.
- 💊 Proscar (Finasteride 5 mg) — 5 mg once daily. Note this is five times the 1 mg dose used for hair loss
- 💊 Avodart (Dutasteride 0.5 mg) — 0.5 mg once daily. Blocks both enzyme types rather than one, lowering DHT further
- 📏 They work only in enlarged glands, conventionally above about 30 to 40 mL, or where PSA is above roughly 1.5. In a small prostate they achieve little, which is why prostate volume is measured before choosing one
- ⏳ Three to six months for benefit, six to twelve for full effect
🩸 These drugs halve your PSA, and that matters for cancer screening. After six months of finasteride or dutasteride, PSA falls by roughly 50 percent. Any PSA measured on treatment must be doubled to be interpreted, and the doctor ordering it has to know you are taking the drug. Otherwise a rising PSA looks normal and prostate cancer is missed. A PSA that rises on treatment, rather than staying halved, is itself a reason for assessment.
The other point to discuss honestly: large prevention trials found fewer prostate cancers overall on these drugs but a small excess of high-grade tumours. The interpretation remains debated, and it belongs in the conversation before starting rather than after.
Sexual side effects occur in a minority: reduced libido, erectile difficulty and reduced ejaculate volume, generally in the low single-digit percentages above placebo. Breast tenderness or enlargement needs assessment rather than waiting.
🔹 Tadalafil: the option that covers two problems
Cialis (Tadalafil) at 5 mg once daily is licensed for the urinary symptoms of prostate enlargement as well as for erectile dysfunction, and it improves the symptom score by an amount comparable to an alpha-blocker.
Its particular value is that erectile dysfunction and prostate symptoms coexist in a large proportion of men over 50, and one tablet addresses both. It also avoids the ejaculatory effects of tamsulosin, which matters to some men more than anything else about the treatment. It is not combined with nitrates, and our guide to erectile dysfunction covers that in detail.
🔹 Combination therapy
For men with larger prostates and moderate to severe symptoms, an alpha-blocker plus a 5-alpha reductase inhibitor outperforms either alone, and in long-term trials the combination reduced progression, acute retention and the need for surgery more than monotherapy. The logic is straightforward: one drug handles the next two weeks, the other handles the next ten years.
Where urgency and frequency persist after obstruction is relieved, an antimuscarinic such as Detrol (Tolterodine) may be added for the bladder component, but only with monitoring, because reducing bladder contraction on top of an obstruction can precipitate retention. Our guide to bladder urgency covers that sequence.
⛔ Medicines that make it worse
This list belongs on the fridge, because several of the drugs on it are bought without a prescription and any of them can tip a narrowed outlet into acute retention.
| Avoid or use with care | Why |
|---|---|
| Decongestants — pseudoephedrine, phenylephrine | Tighten the bladder neck. In cold remedies and combination flu products |
| First-generation antihistamines — diphenhydramine, promethazine, dimenhydrinate | Anticholinergic, reducing bladder contraction. In many sleep aids and travel sickness tablets |
| Antimuscarinics for bladder urgency | Useful in the right man, risky without monitoring |
| Tricyclic antidepressants | Strongly anticholinergic |
| Opioids | Reduce bladder contraction; a classic cause of retention after surgery |
| Anaesthesia and immobility | Retention after an operation is common in men with untreated BPH, which is worth flagging before planned surgery |
🚶 What to change before and alongside the tablets
For mild symptoms these are the treatment rather than an adjunct, and they continue to matter afterwards.
- Shift fluids earlier, do not cut them
- Total intake stays normal, because concentrated urine irritates the bladder. Stop drinking two to three hours before bed, which is the single most effective change for night-time waking.
- Reduce caffeine and alcohol
- Both are diuretics and both irritate the bladder directly. Alcohol in the evening is a reliable cause of a bad night.
- Double voiding
- After passing urine, wait fifteen to thirty seconds, relax, and try again. It measurably reduces residual urine and the frequency that follows from it.
- Sit to urinate
- Studies using flow measurement show better emptying and lower residual volume sitting than standing in men with BPH.
- Treat constipation
- A loaded rectum presses directly on the bladder and prostate, and relieving it improves symptoms more than most men expect.
- Bladder retraining
- Gradually extending the interval between visits, rather than going at the first sensation, which otherwise trains the bladder to signal at smaller volumes.
- Review the medication list
- Including the diuretic timing, which can be moved to the morning.
- Exercise and weight
- Physical activity is associated with slower progression, and metabolic syndrome with worse symptoms.
🌿 Saw palmetto does not work, and the evidence is unusually clear. It is the most widely sold supplement for prostate symptoms, and two large well-conducted randomised trials, including one testing escalating doses up to three times the usual amount, found no difference from placebo in symptom score, flow rate or residual volume. It is harmless and it is not a treatment. Pygeum and beta-sitosterol have weaker evidence still.
🩺 When medication is not enough
Surgery is considered where symptoms remain severe despite drugs, or where there has been retention, recurrent infection, bladder stones or kidney impairment.
- 🔧 TURP — the long-standing reference procedure, removing obstructing tissue through the urethra. Highly effective; retrograde ejaculation afterwards is usual and should be discussed beforehand
- 💡 Laser enucleation or vaporisation — comparable results with less bleeding, suitable for larger glands and for men on anticoagulants
- 💨 Water vapour therapy and prostatic urethral lift — minimally invasive, day-case, with a lower risk of sexual side effects and a somewhat higher chance of needing repeat treatment
- 🏥 Open or robotic prostatectomy for BPH — reserved for very large glands
One point men consistently want answered: these procedures do not cause erectile dysfunction in most cases, but they very commonly change ejaculation, and that distinction is worth having clearly before consenting.
📞 When to see a doctor
- Symptoms affecting sleep or daily routine — earlier treatment preserves more options
- Blood in the urine, at any time
- Straining, dribbling, or a sensation of never emptying
- Any episode of being unable to pass urine
- Repeated urinary infections
- A rising PSA, including one that rises while on finasteride or dutasteride
- Bone pain, weight loss or back pain with urinary symptoms
- Breast tenderness or enlargement on a 5-alpha reductase inhibitor
- Before cataract surgery, if you have ever taken an alpha-blocker
- Before any planned operation, so retention risk can be anticipated
❓ Frequently asked questions
What is the best treatment for an enlarged prostate?
It depends on prostate size and what bothers you. An alpha-blocker such as tamsulosin works within days and suits most men whose problem is symptoms. A 5-alpha reductase inhibitor shrinks the gland over months and suits larger prostates. Tadalafil 5 mg daily covers both urinary symptoms and erections.
How quickly should the tablets work?
Alpha-blockers within a few days to two weeks. 5-alpha reductase inhibitors take three to six months, with full effect at six to twelve. Almost every complaint that a prostate tablet is not working comes from expecting the second to behave like the first.
Why has my ejaculate disappeared on tamsulosin?
Because the drug relaxes the bladder neck so it no longer closes during ejaculation. It is harmless and reverses on stopping, and it is the commonest reason men discontinue the drug. Tadalafil is an alternative that does not do this.
Does finasteride affect the PSA test?
Yes. Finasteride and dutasteride halve PSA, so any result on treatment must be doubled for interpretation and the doctor ordering it must know. A PSA that rises rather than staying halved is a reason for assessment.
Does prostate size determine how bad the symptoms are?
Poorly. How the bladder has adapted matters as much as the gland. A modestly enlarged prostate with an irritable bladder can cause worse symptoms than a very large one, which is why treatment is chosen on symptoms and size together.
Should I stop drinking in the evening?
Stop two to three hours before bed, but keep total daily intake normal, because concentrated urine irritates the bladder. Reducing evening caffeine and alcohol helps as much as the timing.
Which over-the-counter medicines should I avoid?
Decongestants containing pseudoephedrine or phenylephrine, and first-generation antihistamines such as diphenhydramine and promethazine, which are in many sleep aids, cold remedies and travel sickness tablets. Both can precipitate acute retention.
Why must I tell the eye surgeon about my prostate tablet?
Alpha-blockers cause intraoperative floppy iris syndrome, which complicates cataract surgery if unexpected. Stopping the drug beforehand does not reliably prevent it, so the surgeon needs to know, including if you took one in the past.
Does saw palmetto help?
No. Two large randomised trials, including one using escalating doses up to three times the usual amount, found no difference from placebo in symptom score, flow rate or residual volume. It is harmless and it is not a treatment.
Will prostate surgery affect my sex life?
Erectile function is preserved in most cases, but ejaculation very commonly changes, with semen passing backwards into the bladder. That distinction is worth settling clearly before consenting, and the minimally invasive options have lower rates of it.
📑 Sources and editorial
- Urology guidelines on the management of lower urinary tract symptoms attributed to benign prostatic hyperplasia, including IPSS-based treatment thresholds
- Long-term combination therapy trials of an alpha-blocker with a 5-alpha reductase inhibitor on progression, acute retention and surgery
- Prescribing information for tamsulosin, terazosin, doxazosin, finasteride, dutasteride and tadalafil
- Guidance on PSA interpretation during 5-alpha reductase inhibitor therapy, and the prevention trial findings on tumour grade
- Reports of intraoperative floppy iris syndrome with alpha-blocker exposure
- Randomised trials of saw palmetto, including the dose-escalation study showing no benefit over placebo
- Related reading: erectile dysfunction, bladder urgency and spasms
- Related products: Flomax (Tamsulosin), Proscar (Finasteride 5 mg), Avodart (Dutasteride), Cialis (Tadalafil), men's health category
- RXshop Editorial Team — reviewed by Michael Reeves, MD, FACS — Urologist & Men's Health Specialist
Medical Disclaimer: The information in this article is for educational and informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek guidance from a qualified healthcare provider with any questions you may have regarding a medical condition, and before starting, stopping or changing any medication.