Saw palmetto is a plant extract derived from the berries of Serenoa repens, a palm native to the southeastern United States. It has been used in traditional medicine for urinary and prostate health, and more recently has been marketed extensively as a natural alternative to finasteride for hair loss. Understanding what the evidence shows is essential for informed decision-making.
The proposed mechanism is similar to finasteride: saw palmetto inhibits 5-alpha reductase, the enzyme that converts testosterone to DHT. The key difference is potency. Finasteride achieves approximately 70% inhibition of 5-alpha reductase type II; saw palmetto achieves a much smaller inhibition at typical supplement doses, and the standardisation of active ingredient concentration varies widely between products.
The clinical evidence for saw palmetto in androgenetic alopecia is limited but modestly positive. A few small randomised trials have shown reductions in hair loss and some improvements in density compared to placebo, though the effect sizes are smaller than those seen with finasteride. One trial that directly compared saw palmetto to finasteride found finasteride significantly more effective.
Saw palmetto appears safe in most adults, with few significant side effects reported in the literature. This makes it a reasonable option for patients who are concerned about finasteride’s side effect profile and want to try a milder intervention first — with the understanding that the evidence for efficacy is weaker.
Do not source saw palmetto products from unregulated suppliers without knowing the standardised extract concentration. Variability in active ingredient content between products makes it impossible to compare results between different brands.
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