Flomax vs Cialis vs Saw Palmetto: What the Trials Actually Measure

Three things get suggested for an ageing prostate, and they are rarely compared in the same sentence: tamsulosin, sold as Flomax; tadalafil, sold as Cialis, at 5 mg once a day; and saw palmetto, sold in every pharmacy without a prescription. One is a muscle relaxant, one was a drug for erections before it was a drug for urination, and one is a berry extract.

The useful question is not which of them works. All three beat a sugar pill in trials. The useful question is by how much, and whether that difference is large enough for a man to feel. On that question the evidence is unusually clean, because two of the three were measured against the same placebo in the same study.

The trial that put Flomax and Cialis in the same room

In 2012 a trial published in European Urology randomised 511 men with prostate symptoms into three arms: tadalafil 5 mg daily, tamsulosin 0.4 mg daily, or placebo, for twelve weeks. Roughly 170 men in each.

The symptom score used was the IPSS, which runs from 0 to 35. Higher is worse. Here is what happened to it:

Tadalafil improved by 6.3 points. Tamsulosin improved by 5.7 points. And placebo improved by about 4.2 points.

That last number is the one worth sitting with. Men who took nothing at all improved by more than two thirds of what the drugs delivered. Prostate symptoms fluctuate, men enrol in trials when things are bad, and things then tend to drift back toward their average whether or not anything was done. Any account of these treatments that quotes the before-and-after number without the placebo arm is telling you mostly about that drift.

Subtract it, and what each drug actually added was 2.1 points for tadalafil (p = 0.001) and 1.5 points for tamsulosin (p = 0.023). Both real. Both small. And statistically indistinguishable from each other — the trial's own conclusion was that the two worked similarly.

Where saw palmetto lands on the same scale

Saw palmetto has been studied more than most supplements, and the pooled answer arrived in 2023. A Cochrane review brought together 27 trials and 4,656 men. For saw palmetto on its own against placebo, measured on that same IPSS scale, the difference was 0.90 points (95% CI 1.74 to 0.07 in favour of saw palmetto), from nine trials and 1,681 men. Cochrane rated the certainty of that estimate as high, which is rare, and concluded that saw palmetto alone provides little to no benefit.

So the three line up like this, all measured the same way, all against placebo:

Tadalafil 2.1 points. Tamsulosin 1.5 points. Saw palmetto 0.9 points.

Why none of those numbers is as impressive as it sounds

In 1995 Barry and colleagues asked a straightforward question: how much does this score have to move before a man notices? They matched score changes against patients' own global ratings of whether they felt better. The answer usually quoted from that work is three points for a slight perceptible improvement.

Every number in the section above is below three.

The threshold is not a fixed line — the same work shows it depends on where you start. A man with a baseline score of 10 may notice a change of about a point; a man at 30 may need eight. So the honest statement is not "none of these works". It is that the average man in these trials got an improvement smaller than the average man can reliably feel, and that the difference between the prescription options and the supplement is about 1.2 points, which is smaller still.

This is why men try one, feel something, and are not sure whether it is working. The effect sizes are genuinely in that range.

Flow rate is the weakest part of the evidence for all three

Symptom scores and flow rate measure different things, and they do not move together. In the 2012 trial both drugs improved maximum flow similarly against placebo, but across the wider literature flow is where these treatments look thinnest: an earlier placebo-controlled trial of tadalafil found no significant change in flow or in the urine left behind after voiding, and Cochrane found no flow benefit for saw palmetto.

If your problem is a weak stream rather than frequency and urgency, this whole category is the wrong place to look, and that is a conversation for a urologist rather than a shelf.

The side effects are what actually separate them

If the symptom numbers are close, the choice is made somewhere else, and that somewhere is tolerability and what else the drug does.

Tamsulosin relaxes smooth muscle in the bladder neck and prostate. Its characteristic side effect is ejaculatory: reduced or absent semen, which is harmless and reversible but unwelcome, and which shows up more often on tamsulosin than on saw palmetto in head-to-head work. It can also drop blood pressure on standing, most in the first weeks. If you are heading for cataract surgery, tell the surgeon you take it: it is associated with intraoperative floppy iris syndrome, and they will want to know in advance.

Tadalafil at 5 mg treats two things at once. If erectile dysfunction is also in the picture — and in this age group it very often is — one tablet covers both, which no other option on this page does. Its hard limit is nitrates: the combination can drop blood pressure dangerously, and it is an absolute contraindication, not a caution.

Saw palmetto is the easiest of the three to tolerate. Cochrane found little to no difference in adverse events against placebo. That is its real selling point, and it is a genuine one: if your symptoms are mild and you want to do something with almost no downside, this is a defensible choice. It is just not a defensible choice on the grounds that it works well.

Can you take Flomax and Cialis together?

Often yes, and the detail matters more than the headline.

A 2004 study in healthy men tested tadalafil against two different alpha blockers and found they behave quite differently. With doxazosin, 28% of men had their standing blood pressure fall below 85 mmHg, against 6% on placebo. With tamsulosin, not one man in the study fell below that line.

Tamsulosin is the alpha blocker that sits most comfortably alongside tadalafil, which is why the combination is used in practice. That is not a licence to start both at once on your own. Starting two blood-pressure-lowering drugs together is how people end up on the floor, and the sequencing is a decision for the person prescribing.

So which one

The trials do not hand you a winner, and anyone presenting one is reading them loosely. What they support is narrower and more useful:

If erections are also a problem, tadalafil is the only option here that addresses both, and it had the largest symptom effect of the three. If your main concern is side effects and your symptoms are mild, saw palmetto is close to harmless and close to ineffective, and those two facts travel together. If you are already on tamsulosin and considering adding saw palmetto, a year-long trial of that exact combination found it added nothing measurable.

And if your score is high enough that two points would not register, the honest answer is that none of these is the right size of intervention, and the conversation to have is about the procedures none of them replace.