Saw Palmetto Side Effects: Is This Hair Loss Herb Safe?

By Paul Taylor

It’s ironic isn’t it? You don’t want to risk using Propecia, but then suffer saw palmetto side effects instead!

This article explains the possible side effects from using saw palmetto to treat hair loss, and what the risks are for men, women and children.

1. Is Saw Palmetto Safe for Women?

The drug product Propecia (finasteride) carries a warning that it shouldn't be used by women. Any pregnant woman (or woman likely to become pregnant) who comes into physical contact with it, runs the risk of causing sexual defects in her unborn baby if it’s a boy (1).

Saw palmetto is often said to be a safe, natural alternative to finasteride, but it does appear to work the same way - by blocking DHT (dihydrotestosterone). And that means it's also likely to have the same side effects as finasteride.

Obviously then, if a pregnant woman were to take saw palmetto, she may be running the risk of blocking DHT production in an unborn baby boy and causing side effects as he develops in the womb.

However, despite all this, most saw palmetto products do not state "for men only".

Risks of saw palmetto side effects

2. A Hidden Side Effect for Men?

This potential problem concerns prostate cancer. Saw palmetto might hide the signs of prostate cancer development by reducing levels of a protein that can be used to detect it. First, here's the background:

How saw palmetto helps men with prostate problems

Studies have shown that saw palmetto berries can be effective against prostate gland growth (called benign prostatic hyperplasia or BPH*) (2) and prostate cancer (3).

* BPH is an uncomfortable condition that generally affects older men whereby an enlarged prostate gland can interfere with urinary action and lead to further health problems which, unfortunately, can include prostate cancer.

High DHT levels have been linked to prostate growth. So, by reducing DHT availability, a reduction in prostate gland size can occur, thereby relieving the symptoms of BPH. There are three possible ways in which saw palmetto might be able to help:

  • By blocking the enzyme 5-alpha reductase from converting testosterone into DHT.

  • It can stop DHT binding to androgen receptors.

  • It may also have an anti-inflammatory effect and oppose growth factors.

Since saw palmetto extract can reduce symptoms of BPH, this raises the tantalizing prospect that saw palmetto can benefit men with hair loss too.

Saw palmetto hair loss research

Given that high DHT levels have been associated with both prostate problems and hair loss, it makes sense that saw palmetto might help tackle hair loss in the exact same way it helps the prostate gland.

But the effectiveness of saw palmetto treatment for hair loss is not quite as certain as it is for the prostate gland - there’s a lot of conflicting information (and disinformation) out there.

Uncertainties surrounding hair loss treatment using saw palmetto

Here are just some of the contradictions and confusion surrounding the use of saw palmetto for hair loss:

  • Although saw palmetto acts on 5-alpha reductase and DHT receptors in the prostate gland, one or both of these mechanisms may or may not be how saw palmetto acts in the hair follicles.

  • Some studies suggest that saw palmetto only targets the prostate gland. But at least one other scientific study (4) has shown that it targeted all tissues it was exposed to.

  • Saw palmetto is said to be similar to the drug finasteride because both are DHT blockers. But there are differences. For example, finasteride can decrease DHT serum levels (i.e., in the blood) whereas saw palmetto cannot*. This suggests that saw palmetto would have a lesser effect than finasteride.

  • However, finasteride acts on just 5-alpha reductase type II, whilst saw palmetto acts on both (5) type I and II*. So this might suggest that saw palmetto has an even greater effect than finasteride.

* These differences probably mean that any side effects experienced from taking saw palmetto might not be exactly the same (or perhaps not as extreme) as the side effects from finasteride. Saw palmetto is, after all, a naturally-occurring herb. So, whilst it's often taken in a concentrated form, you might expect it to be safer than a drug product.

I believe one other reason why saw palmetto is known to be so effective against prostate problems but is much more questionable when it comes to hair loss, is because hair loss is caused by skull expansion. And I’m pretty sure skull expansion doesn’t affect the prostate gland!

So that now brings us back to the potentially hidden problem for men...

An added risk of side effects in men with prostate problems who take saw palmetto?

BPH patients are regularly blood tested for a protein called prostate-specific antigen (PSA), high levels of which can indicate and help detect possible prostate cancer.

However, one possible side effect of saw palmetto is that it might* lower PSA levels. And this means that if the results of a PSA test are low, it could be that any saw palmetto product the patient is taking might hide the signs of prostate cancer.

Early detection and treatment of cancer is obviously extremely important. So if you’re a man with prostate problems, and you’re taking saw palmetto (for either hair loss or your prostate), then for safety sake you’d better make sure your doctor knows about it.

* Note: Most studies show that saw palmetto does not decrease PSA levels. But some medically qualified concerns have been voiced which warn that, given time, it does.

3. Upregulation

As already mentioned, the main reason why men and women use saw palmetto hair loss products is to try and reduce DHT levels in their hair follicles. The idea being that, since DHT is involved in the hair loss process, lower DHT levels might help.

Well, nice idea, but there’s a potential problem – upregulation (or hyperandrogenicity). This simply means that your body can react to saw palmetto (or any other DHT blocker you might use) by producing even more DHT.

The result?

Even more hair loss!

And some saw palmetto side effects reported do include an increase in hair loss (as is often the case with other DHT blocker agents including finasteride).

After some unknown period (weeks? months?) this extra shedding might reduce back down again as DHT levels finally start to stay low. But this can lead to another problem:

4. Estrogen Instead of DHT?

Most research suggests that saw palmetto decreases estrogen levels, but an FDA warning states that DHT blocker products can increase estrogen levels.

That’s because, by blocking the enzyme 5-alpha reductase from converting testosterone into DHT, it may well be that another enzyme (aromatase) can convert some of that surplus testosterone into estrogen instead.

Here’s a very simplified look at the normal, predominant hormone pathway for men and women:

Men: Testosterone + 5-alpha reductase = DHT
Women: Testosterone + aromatase = Estrogen

Note: both men and women produce testosterone and the enzymes 5-alpha reductase and aromatase.

So if excessive levels of testosterone get converted into estrogen in men, that can be a problem because, like DHT, the role of estrogen is to promote growth. Elevated estrogen levels in men might cause prostate gland growth (as discussed earlier).

And that is a big concern because, in 2011, the FDA issued a warning that men using DHT blocker drugs (including finasteride) are at greater risk of developing an aggressive form of prostate cancer.

So, since saw palmetto appears to act in the same way as these drugs, you might do well to avoid taking any type of DHT blocker, be it a drug or natural alternative.

Bottom line?

You might not want hair loss, but you definitely don’t want prostate cancer! 

5. More Saw Palmetto Side Effects

Most people don’t experience any problems taking saw palmetto. But some do, and have reported the following:

  • Dizziness or headaches

  • Feeling sick (including vomiting)

  • Constipation or diarrhea

Some websites also state that saw palmetto can cause sexual dysfunction in men (breast enlargement, impotence, etc). But most sites state that there are no such side effects.

You can compare the side effects of saw palmetto on this page with those of Propecia in my finasteride side effects review.

But It Did Help the Indians

Despite the potential side effects of saw palmetto mentioned above, this herb has long been used as a health aid. For example, some Native American Indians used saw palmetto for urinary tract and prostate gland health. And many people today take saw palmetto supplements for the same reason (as mentioned above).

Native American Indian

However, I'm pretty sure Native American Indians didn't take supplements.

So, instead of riding on down to their local health food store, they just ate the berries.

And this would have probably given them a much smaller dose of the active ingredients when compared to men today, many of whom consider two 160 mg capsules of standardized saw palmetto extract to be an appropriate daily dosage for hair loss treatment.

But taking 320 mg every single day will clearly mount up to quite a considerable dose of the active ingredients over time. And overdosing on herbs can be like overdosing on drugs.

Whether or not Native American Indians suffered any side effects from eating saw palmetto berries, I don't know. But I do know that they didn’t suffer hair loss as much as Caucasians. And the reason why has got nothing to do with saw palmetto. You can find out why by reading this article.

Despite the uncertainties, many men and women desperate to solve their hair loss problem, try products that contain saw palmetto, and quite often do so as their first choice rather than the FDA approved drugs minoxidil and finasteride.

But, using saw palmetto for hair loss might still lead to the potential side effects as explained above.

If, having learnt all about the possible side effects of saw palmetto, you're still interested in trying this herb, you can compare some of the most popular topical and oral products containing saw palmetto in the hair loss products section:

Read about Oral Saw Palmetto Supplements.

Read about DHT Topical Products.


(1) The following study states that: Risks include birth defects in male fetuses if used in pregnancy: Adverse Effects and Safety of 5-alpha Reductase Inhibitors (Finasteride, Dutasteride): A Systematic Review. J.M. Hirshburg, P.A. Kelsey, et al. J Clin Aesthet Dermatol. 2016 Jul; 9(7): 56–62. Source:

(2) Improving BPH symptoms and sexual dysfunctions with a saw palmetto preparation? Results from a pilot trial. Suter A, Saller R, Riedi E, Heinrich M. Phytother Res. 2013 Feb;27(2):218-26. doi: 10.1002/ptr.4696. Epub 2012 Apr 23. Source: PubMed

(3) Myristoleic acid, a cytotoxic component in the extract from Serenoa repens, induces apoptosis and necrosis in human prostatic LNCaP cells. Iguchi, K; Okumura, N, et al. The Prostate. 47 (1): 59–65. Source: Researchgate

(4) An extract  of saw palmetto reduced uptake of dihydrotestosterone in all eleven different tissue specimens tested: The effect of Permixon on androgen receptors. el-Sheikh MM, Dakkak MR, Saddique A. Acta Obstet Gynecol Scand. 1988;67(5):397-9. Source:

(5) Saw palmetto reduces 5-alpha reductase types I and II: Comparison of the potency of 10 different brands of Serenoa repens extracts. Scaglione F, Lucini V, et al. Eur Rev Med Pharmacol Sci. 2012;16:569–574. Source:

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