Saw Palmetto

Serenoa repens · Sabal serrulata · Saw palmetto berry

Snapshot

Indications	Contraindications
Benign prostatic hyperplasia symptoms¹ Nocturia^{1, 2} Androgenetic alopecia^{3, 4} Self-perceived thinning hair^{5, 6}	Anticoagulant use⁷ Antiplatelet use⁷ Pregnancy or breastfeeding⁸ Hypersensitivity to saw palmetto⁹

Saw palmetto (Serenoa repens) is the berry extract of a small North American palm, promoted for urinary symptoms of benign prostatic hyperplasia (BPH) and for male pattern hair loss⁸. It works largely by blocking testosterone conversion to dihydrotestosterone (DHT), alongside anti-inflammatory activity⁷.

For BPH, a randomized trial found saw palmetto at up to triple the standard dose did no better than placebo for urinary symptoms¹⁰. Meta-analyses restricted to the hexanic extract report fewer nighttime voids and higher peak urinary flow^{1, 2}. For hair, small oral and topical trials report gains in hair density, though the sole contribution of saw palmetto remains unconfirmed.¹¹ A 2025 review of blinded controlled trials of non-prescription androgenetic alopecia monotherapies, including saw palmetto, reported improved hair parameters across agents. Products are capsules, softgels, and liquids, from powdered berry to hexanic or carbon dioxide extracts; see Form comparison.

Bleeding is the reason behind the anticoagulant caution: Memorial Sloan Kettering Cancer Center lists case reports of prolonged bleeding time and intraoperative hemorrhage⁷. Per the European Medicines Agency monograph, suspected warfarin interactions raised international normalized ratio values⁹, and Health Canada labels ask for a practitioner's advice before use to exclude prostate cancer¹².

Last updated October 16, 2026. Read how we make monographs.

In the full monograph

71 sources, 59 studies

When to useThe situations practitioners use it for, each with the reason and the study behind it.
SafetyWho should avoid it, who needs extra care, and the side effects reported in studies.
InteractionsThe medicines and supplements it interacts with, the effect of each, and what labeling says to watch.
Protocol notesThe doses used in studies, how and when they were taken, and how the forms on the market compare.
How it worksWhat it is and how it works in the body, in plain terms.
Published studiesThe studies behind each use, popular claims checked against them, and trials still under way.
Word of mouthWhat patients and practitioners report online, kept separate from the clinical evidence.
Clinical perspectiveA closing read of where the evidence is solid, where it is thin, and what has not been studied.

Snapshot

In the full monograph

Sources