Can Saw Palmetto Halt Hair Loss?

Saw Palmetto Serenova repens
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If you've been reading about natural remedies for hair loss, you may have come across an herb called saw palmetto. Sourced from the berries of a North American plant known as Serenoa repens or Sabal serrulata, saw palmetto extracts are said to help slow or reduce the type of hereditary hair loss known as androgenic alopecia (a common form of hair loss also known as male- or female-pattern baldness).

Saw palmetto is sometimes touted as a natural treatment for other health conditions, such as acne, benign prostatic hyperplasia (BPH), erectile dysfunction (ED), and polycystic ovary syndrome (PCOS).

Benefits for Hair Loss

According to a 2019 review of complementary and alternative treatments for alopecia, saw palmetto is believed to work by inhibiting the activity of 5-alpha-reductase, an enzyme involved in the conversion of the hormone testosterone to dihydrotestosterone (DHT). DHT is considered a key contributing factor to the onset and progression of androgenic alopecia. Saw palmetto also is believed to increase the activity of an enzyme responsible for the metabolism of DHT into androstanediol (a weaker androgen hormone).

While there's still a need for large, well-designed clinical trials of saw palmetto, the review concludes that this treatment—both taken orally or used topically (on the scalp)—does have clinical benefits and might be a good alternative for men who can't or don't want to take oral finasteride, which is a common drug treatment for hair loss. However, researchers say saw palmetto is not superior to standard drug treatments.

A review published in late 2019 in the Archives of Dermatological Research lists saw palmetto as one of the plants with the most evidence-based effect against alopecia.

While this early research is promising, more research must be done before we'll know for certain how well saw palmetto works and how safe it is for long-term use.

Possible Side Effects

As with other herbal supplements, little is known about the side effects of long-term use or high doses of saw palmetto.

Side effects observed in studies have typically been mild and taper off with continued use. They include:

  • Stomach pain
  • Constipation
  • Diarrhea
  • Nausea
  • Vomiting
  • Dizziness
  • Headache
  • Sexual dysfunction, but less often than with finasteride

There's some concern that saw palmetto could cause more serious problems in some people, such as those involving:

  • Liver damage
  • Cholestatic hepatitis
  • Pancreatitis
  • Heart disease or heart rhythm disorder
  • Sex hormones
  • Oral contraceptives
  • Pregnancy or breastfeeding
  • Blood clotting

Some reports of liver injury and pancreatitis in people taking saw palmetto have been made, but so far, there isn't enough information to know whether saw palmetto was the true cause of the adverse reactions.

Although it hasn't been well-demonstrated in humans, saw palmetto may influence levels of sex hormones such as estrogen and testosterone. Until we know more, people with hormone-sensitive conditions, such as breast cancer, should avoid it.

Also, saw palmetto could theoretically interfere with oral contraceptives and hormone therapy, in a similar manner that's similar to the medication finasteride.

Children and pregnant or nursing women shouldn't take saw palmetto.

Saw palmetto could slow blood clotting. People with bleeding disorders or who are taking anticoagulant or antiplatelet medications or supplements, such as warfarin (Coumadin®), aspirin, or clopidogrel (Plavix®), should avoid taking saw palmetto unless under medical supervision. It should also be avoided at least two weeks before and after surgery.

It's important to keep in mind that supplements haven't been tested for safety and are largely unregulated. Make sure to read about using supplements safely.

Using Saw Palmetto

Losing your hair can be distressing. Although it may be tempting to start using saw palmetto, if you're considering using it, be sure to consult your health care provider to discuss whether it's appropriate for you. Most hair loss treatments require regular use, and it's important to consider the current lack of evidence or safety information (especially for long-term use).

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Article Sources
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  1. Hosking AM, Juhasz M, Atanaskova Mesinkovska N. Complementary and Alternative Treatments for Alopecia: A Comprehensive ReviewSkin Appendage Disord. 2019;5(2):72–89. doi:10.1159/000492035

  2. Zgonc Škulj A, Poljšak N, Kočevar Glavač N, Kreft S. Herbal preparations for the treatment of hair loss [published online ahead of print, 2019 Nov 3]. Arch Dermatol Res. 2019;10.1007/s00403-019-02003-x. doi:10.1007/s00403-019-02003-x

  3. University of Michigan, Frankel Cardiovascular Center. Saw Palmetto. Updated August 15, 2015.

  4. Michigan Medicine, University of Michigan Medical School. Saw Palmetto. Updated June 28, 2018.

  5. Lapi F, Gallo E, Giocaliere E, et al. Acute liver damage due to Serenoa repens: a case reportBr J Clin Pharmacol. 2010;69(5):558–560. doi:10.1111/j.1365-2125.2010.03618.x

  6. American College of Cardiology, CardioSmart. Saw Palmetto. Updated December 15, 2010.

  7. PennState Hershey, Milton S. Hershey Medical Center. Saw Palmetto. Updated January 1, 2017.

Additional Reading
  • Rossi A, Mari E, Scarno M, et al. Comparitive effectiveness of finasteride vs Serenoa repens in male androgenetic alopecia: a two-year studyInt J Immunopathol Pharmacol. 2012;25(4):1167–1173. doi:10.1177/039463201202500435

  • Wessagowit V, Tangjaturonrusamee C, Kootiratrakarn T, et al. Treatment of male androgenetic alopecia with topical products containing Serenoa repens extractAustralas J Dermatol. 2016;57(3):e76–e82. doi:10.1111/ajd.12352

  • Prager N, Bickett K, French N, Marcovici G. 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. J Altern Complement Med. (2002) 8.2: 143-152.
  • Ulbricht C, Basch E, Bent S, Boon H, Corrado M, Foppa I, Hashmi S, Hammerness P, Kingsbury E, Smith M, Szapary P, Vora M, Weissner W. Evidence-based systematic review of saw palmetto by the Natural Standard Research Collaboration. J Soc Integr Oncol. (2006) 4.4: 170-186.
  • Wilt TJ, Ishani A, Stark G, MacDonald R, Lau J, Mulrow C. Saw palmetto extracts for treatment of benign prostatic hyperplasia: a systematic review. JAMA (1998) 280.18: 1604-1609.