Saw Palmetto and Tamsulosin (Flomax): Together or Instead?

Two questions come up again and again about saw palmetto and tamsulosin, the drug sold as Flomax. Can you take them together? And can saw palmetto replace tamsulosin? Both have been tested directly, which is unusual for a supplement, and the answers are clearer than most of what is written about them.

Can you take saw palmetto with tamsulosin?

Yes. There is no known interaction between them, and the combination has been through a proper trial. In the OCOS study, 329 men with prostate symptoms took tamsulosin 0.4 mg a day for a year, with either saw palmetto 160 mg twice a day or a placebo. The symptom score improved by 6.0 points with the combination and 5.2 with tamsulosin alone. That difference was not statistically significant. Neither were the differences in flow rate, quality of life or the share of men who responded. Side effects did not differ between the groups.

A smaller three-arm study of 60 men reached the same conclusion: saw palmetto alone, tamsulosin alone and the two together all improved symptoms and flow, and the combination added nothing over either.

So adding saw palmetto to tamsulosin appears safe, and on the evidence it buys you nothing measurable. If you are already on tamsulosin, the money is better spent elsewhere, or not at all.

Is saw palmetto as good as Flomax?

This is where the evidence needs reading carefully, because there is a trial that seems to say yes.

In the PERMAL study, 704 men were randomised to tamsulosin 0.4 mg a day or Permixon, a standardised saw palmetto extract, at 320 mg a day, for a year. Symptom scores fell by 4.4 points in both groups. Flow improved by almost exactly the same amount. Ejaculation problems were more common on tamsulosin. The authors concluded the two were equivalent. In a later analysis of the men with severe symptoms, saw palmetto came out slightly ahead on the irritative symptoms, urgency and frequency.

The catch is that PERMAL had no placebo group. It showed the two treatments did about the same. It could not show either did better than nothing.

That matters because when saw palmetto has been tested against placebo in large, long trials, it has not beaten it. In the 72-week CAMUS trial, 42.6 percent of men on saw palmetto improved meaningfully, against 44.2 percent on placebo, and doubling or tripling the dose made no difference. The Cochrane review of 32 trials found the high-quality long-term trials showed no benefit over placebo.

Put those together and the most consistent reading is not that saw palmetto is as good as tamsulosin. It is that in a year-long trial without a placebo arm, much of the improvement in both groups was the large placebo response that prostate symptoms are known for, and tamsulosin's own advantage over placebo is modest enough to be hard to see in that setting. Tamsulosin has beaten placebo in its own trials. Saw palmetto, in its best ones, has not.

Can you take saw palmetto instead of tamsulosin?

If your symptoms are mild and you have never had retention, trying a supplement before a drug is a reasonable choice, but saw palmetto is the weakest option in the category to try. Beta-sitosterol, rye grass pollen and pygeum all beat placebo in their own trials, and our ranking of prostate supplements goes through each.

If you are already on tamsulosin and want to swap it for saw palmetto, the evidence gives you little reason to expect the same result. If you do try, do it with your prescriber's agreement, keep a two-week log of night-time trips and stream, and go back on tamsulosin if things worsen. If you started tamsulosin after an episode of urinary retention, do not swap it for any supplement.

What about PSA?

A common warning is that saw palmetto lowers PSA and could hide prostate cancer, the way finasteride does. The CAMUS trial measured this directly. Over 72 weeks at up to three times the usual dose, PSA changed by 0.23 ng/ml on saw palmetto and 0.16 on placebo, which was not a significant difference. Saw palmetto does not mask a PSA test. Finasteride and dutasteride do, so if you take either of those with tamsulosin, that is the drug to tell whoever orders your PSA about.

Bleeding and surgery

The safety point worth knowing is a different one. A small number of case reports describe bleeding problems in people taking saw palmetto around surgery. It is rare, and saw palmetto's side effects matched placebo in the trials, but tell your surgeon you take it, and tell your eye surgeon about the tamsulosin, which can cause floppy iris syndrome during cataract surgery even years after stopping.

If you are going to take both anyway

Use the form the trials used: a standardised lipid extract of saw palmetto, 320 mg a day, with 85 to 95 percent fatty acids stated on the label. Powdered berry is a different material and is what the clearly negative trials used. Give it twelve weeks with a written note of your symptoms at the start, and stop if nothing has changed.