Saw Palmetto (Serenoa repens)


Genitourinary health and symptoms of conditions including benign prostatic hyperplasia, chronic nonbacterial prostatitis, and chronic pelvic pain syndrome. Hormonal modulator of estrogen and testosterone, polycystic ovarian syndrome with hirsutism.

Mechanism of Action

Serenoa berries contain approximately 1.5% volatile oil of which 63% are free fatty acids and 38% are ethyl esters of those fatty acids fatty acids known collectively as liposterols. Individually, these liposterols are known as lauric, oleic, myristic, and linoleic acids. All of these fatty acids have been shown to inhibit the enzyme 5α-reductase (5AR).1,2,3 5AR is found in the adrenal glands (and in men, the prostate as well) that converts testosterone into its most active form, dihydrotestosterone. In addition, the berries contain β-sitosterol that has known phytoestrogenic effects.4

The liposterolic extract inhibits 5AR, 3-ketosteroid reductase, and receptor binding of androgens in cultured human foreskin fibroblasts. As the search for the ideal antiandrogen continues, Serenoa seems to be a new type of antiandrogenic compound as therapeutics for the treatment of benign prostatic hypertrophy, hirsutism, and other conditions related to excessive androgen activity.5

Women with hirsutism and elevated testosterone may have excessive 5AR activity. Male pattern baldness, also known as androgenic alopecia in men, and thinning of the hair in women may also be initiated and promoted when 5AR is up-regulated. Serenoa has been shown to promote hair growth compared with placebo in men with androgenic alopecia,6 and the herb might benefit women as well. Elevated androgens are the hallmark of polycystic ovarian syndrome (PCOS) in women. Serenoa has been shown to reduce the uptake of androgens including dihydrotestosterone and testosterone into tissues by 40%.7

Prolactin is typically elevated in women with PCOS and is a leading cause of amenorrhea and infertility. In women with PCOS, elevated prolactin can suppress follicle maturation and ovulation and contribute to ovarian cysts. Animal studies show Serenoa to inhibit prolactin receptors on ovarian cells and reduce the basal activity of K(+) channels and of protein kinase C involved with the transduction of prolactin signals.8

Evidence-Based Research

There has been a great deal of research regarding Serenoa and its ability to treat diseases of the prostate in men, but there is very little research regarding women.

One study evaluated the effects of a Serenoa repens alcohol extract treatment on benign prostatic hyperplasia (BPH) patients’ symptoms and major parameters during 1-year follow-up. The study was performed on 70 men aged 40–79 years with symptomatic BPH that were divided into a group of 40 patients treated with S. repens extract (SRT) and a control group of 30 patients that received no treatment and were observed only. The patients in the SRT group showed improvements in urine flow and prostate size.9

In another double-blind, placebo-controlled study of 110 patients with BPH, 160 mg of a standardized Serenoa extract given twice a day was found to significantly improve symptoms of nocturia, dysuria, postvoiding residual urine, and flow rate among other positive parameters.10

Environmental toxins can disrupt reproductive development and function by both mimicking and inhibiting endogenous steroids,11 thereby contributing to infertility, PCOS, hormonal cancers, thyroid disease, and other ailments. Serenoa may help reduce elevated androgens and prolactin typically seen in women with PCOS, as animal studies have shown Serenoa to block prolactin receptors on ovarian cells overexpressing prolactin receptors.8

Safety in Pregnancy and Breastfeeding

There is currently no information on the safety of Serenoa in pregnancy or lactation in the scientific or traditional literature.

General Safety

There has been an anecdotal report of a single incidence of cholestatic hepatitis in a patient using Serenoa; however, several dosage ranges about the normal human dosage, 9.14 or 22.86 mg/kg/body weight/day, did not elevate liver enzymes or any other biomarkers of liver toxicity in rat.12 Another rat study showed no evidence of hepatotoxicity at 150 and 300 mg/kg.13

A detailed safety assessment on 225 men using 160 mg of Serenoa twice a day found no significant side effects or toxicity compared with placebo.14 Occasionally, patients experience minor gastrointestinal symptoms such as nausea and abdominal pain. Serenoa may interact with pharmaceuticals via cytochrome p450 effects.15,16,17


Serenoa is generally considered safe at doses up to 900 mg/day. Standardized liposterolic extracts containing 45%–95% fatty acids and sterols have been used in the majority of clinical studies.

Traditional Uses

Serenoa repens extracts have been used for centuries in the treatment of benign prostatic hyperplasia. Classic herbal books and folkloric traditions report Serenoa to be a genitourinary tonic in both sexes.



Biol Pharm Bull. 2009;32(4):646–50. Pharmacologically relevant receptor binding characteristics and 5alpha-reductase inhibitory activity of free Fatty acids contained in saw palmetto extract. Abe M, Ito Y, Oyunzul L, Oki-Fujino T, Yamada S.

2 J Steroid Biochem Mol Biol. 2002;82(2–3):233–9. Inhibition of type 1 and type 2 5alpha-reductase activity by free fatty acids, active ingredients of Permixon. Raynaud JP, Cousse H, Martin PM.

3 Cas Lek Cesk. 2002;141(20):630–5. Enzyme inhibition in the drug therapy of benign prostatic hyperplasia. Drsata J.

4 Handbook of Medicinal Herbs. Boca Raton, FL: CRC Press; 1985. p. 443. Duke J.

5 J Steroid Biochem. 1984;20(1):515–9. Inhibition of Androgen Metabolism and Binding by a Liposterolic Extract of “Serenoa repens B” in Human Foreskin Fibroblasts. Sultan C, et al.

6 J Altern Complement Med. 2002;8(2):143–52. A randomized, double-blind, placebo-controlled trial to determine the effectiveness of botanically derived inhibitors of 5-alpha-reductase in the treatment of androgenetic alopecia. Prager N, Bickett K, French N, Marcovici G.

7 Acta Obstet Gynecol Scand. 1988;67(5):397–9. The effect of Permixon on androgen receptors. el-Sheikh MM, Dakkak MR, Saddique A.

8 J Biomed Sci. 1995;2(4):357–65. The lipidosterolic extract from Serenoa repens interferes with prolactin receptor signal transduction. Vacher P, Prevarskaya N, Skryma R, Audy MC, Vacher AM, Odessa MF, Dufy B.

9 Pril (Makedon Akad Nauk Umet Odd Med Nauki). 2017;38(2):123–9. Effects of Serenoa repens alcohol extract on benign prostate hyperplasia. Saidi S, et al.

10 Br J Clin Pharmacol. 1984;18(3):461–2. A double-blind trial of an extract of the plant Serenoa repens in benign prostatic hyperplasia. Champault G, et al.

11 J Mol Med (Berl). 1997;75(3):198–207. Environmental antiandrogens: developmental effects, molecular mechanisms, and clinical implications. Kelce WR, Wilson EM.

12 Phytomedicine. 2007;14(2–3):204–8. Hepatotoxicity potential of saw palmetto (Serenoa repens) in rats. Singh YN, Devkota AK, Sneeden DC, Singh KK, Halaweish F.

13 Eur Rev Med Pharmacol Sci. 2011;15(11):1311–7. Tolerability and toxicity of lipidosterolic extract of American dwarf palm Serenoa repens in Wistar rats: well-known extract, new insight. Duborija-Kovacevic N, Jakovljevic V, Sabo A, Tomic Z, Pajovic B, Perovic D.

14 Complement Ther Med. 2008;16(3):147–54. A detailed safety assessment of a saw palmetto extract. Avins AL, Bent S, Staccone S, Badua E, Padula A, Goldberg H, Neuhaus J, Hudes E, Shinohara K, Kane C.

15 Clin Pharmacol Ther. 2004;76(5):428–40. In vivo assessment of botanical supplementation on human cytochrome P450 phenotypes: Citrus aurantium, Echinacea purpurea, milk thistle, and saw palmetto. Gurley BJ, Gardner SF, Hubbard MA, Williams DK, Gentry WB, Carrier J, Khan IA, Edwards DJ, Shah A.

16 Br J Clin Pharmacol. 2013;75(3):603–18. Herb-drug interactions: an overview of systematic reviews. Posadzki P, Watson L, Ernst E.

17 Clin Pharmacol Ther. 2003;74(6):536–42. Multiple doses of saw palmetto (Serenoa repens) did not alter cytochrome P450 2D6 and 3A4 activity in normal volunteers. Markowitz JS, Donovan JL, Devane CL, Taylor RM, Ruan Y, Wang JS, Chavin KD.