Saw Palmetto: Benefits, Side Effects, Best Time to Take It & More (2025)

Saw Palmetto

(Serenoa Repens)

Evidence: Low
Possible Benefits: Low
Safety: Low

What is saw palmetto?

Saw palmetto is a mix of fatty acids from Serenoa repens, an adaptogenic herb with a long history of use as a traditional medicine. This herb is often used as a supplement for suppressing prostate growth and improving hormonal health. Unfortunately, these effects have never been proven by quality studies and have been disproven multiple times. This article is about the main benefits of saw palmetto, its potential side effects, the best time to take it, and more.

Possible benefits

All of the potential benefits mentioned below are dose-dependent. As with other adaptogenic herbs, there is a sweet-spot dose that allows you to get most of the benefits without causing meaningful side effects or tolerance buildup in the body. We will discuss the best dosing protocol later in this article.

Major benefits

Improved prostate surgery outcomes – Taking 320 mg of saw palmetto daily for 2 months was able to improve surgery outcomes in people undergoing TURP (transurethral resection of the prostate).

Minor benefits

Increased hair growth in men – Daily supplementation of 320 mg for 2 years increased hair growth in 38% of users with male pattern baldness.

Possible side effects

The side effects below are dose-dependent. The risk for them increases (often linearly but sometimes exponentially) as you increase the dose. Some of the side effects only apply to very high doses.

Iron deficiency – Saw palmetto contains tannic acids, which bind to iron and reduce bioavailability.
Minor sexual dysfunction – Some people who take saw palmetto develop minor sexual dysfunction, likely because of the supplement’s pro-estrogenic effects.
Nausea – This side effect is most common when people take the herb on an empty stomach.
Diarrhea – You can usually prevent diarrhea or stomach discomfort by taking this herb with a meal.
Toxicity – As an adaptogen, saw palmetto acts as a mild stressor on the body. That is usually a great thing as it allows your body to adapt to specific forms of stress and become more resilient. However, stressing the body too much can be counter-productive and cause multiple side effects, including toxicity. While acute toxicity is extremely rare, taking very high amounts of this herb could lead to chronic toxicity and cause health problems over time. To prevent chronic toxicity or the buildup of tolerance, staying below 500 mg of saw palmetto a day is best unless you have a great reason to take more.
Contamination– If growing or storing conditions are not adequately controlled, saw palmetto can be contaminated with bacteria, molds, and other potentially harmful microorganisms. Some growers also use pesticides and herbicides, some of which are unsafe. Another issue is that herbal supplements can get contaminated with other supplements and chemicals during the manufacturing process. Choose the brand you get herbs and herbal supplements from wisely. It is often best to use websites like Amazon, where thousands of users have reviewed and rated the products. You are less likely to buy something of lower quality there.

Who should not take saw palmetto?

You should probably avoid taking saw palmetto if you:

are allergic to this herb
experience a severe adverse reaction after taking the herb (though a mild adverse reaction is usually a great thing as it is a sign that the supplement is working and causing a hormetic response that allows the body to adapt and become more resilient)
are pregnant or breastfeeding (while it can be safe to take this adaptogen during pregnancy or breastfeeding, it acts as a mild stressor and can cause some unnecessary risk to the child)
suffer from an autoimmune disease (adaptogenic herbs can stimulate the immune system, which can worsen symptoms of autoimmune diseases, such as lupus or multiple sclerosis)

Who will benefit the most?

You should consider taking the supplement if you:

are about to go through prostate surgery (taking 320 mg of saw palmetto daily for 2 months was able to improve surgery outcomes in people undergoing transurethral resection of the prostate, also known as TURP)

How much saw palmetto should you take?

Because saw palmetto is an adaptogenic herb, it acts as a mild hormetic stressor on the body, which allows your body to adapt and become more resilient to certain kinds of stressors in the long term.

A higher dose does not necessarily lead to more pronounced benefits. Instead, there appears to be an inverted U-shaped dose-response pattern. In other words, you want to find a sweet-spot dose that allows you to get the benefits of saw palmetto without putting too much stress on the body or quickly causing the body to develop tolerance to the herb.

The sweet-spot dose typically ranges anywhere between 160-320 mg of saw palmetto daily. If you buy an extract standardized for fatty acids and sterols (liposterolic compounds), the sweet spot is about 130-260 mg of fatty acids and sterols.

The higher end of this range usually provides slightly more benefits in the short term. If you plan to take this herb for a longer time (multiple months or years), the lower end is probably a better way to go since you would develop tolerance faster if you were to take higher doses.

While higher doses are generally safe, taking more than the sweet-spot dose daily would be counter-productive as your body would quickly develop tolerance.

Additionally, very high doses can put too much stress on your system and cause health problems if you take the supplement for a prolonged period.

While this herb could theoretically cause acute toxicity, you would need to take an extremely high dose that is way beyond what is generally found in even the most potent supplements.

Like with most other adaptogens, it is best to cycle saw palmetto and take about 2 days off every week to reset your tolerance. This will allow you to keep getting the benefits in the long term.

Keep in mind that the effects of this herb are cumulative. Therefore, you must take it for at least 2-4 weeks to notice the benefits. But again, cycling the herb and not taking it at least twice a week is necessary to prevent tolerance in the long term.

Best time to take saw palmetto

You can take this herb with or without food. Each of these options has its benefits. The main bioactive compounds in the herb should absorb well either way.

If you experience nausea or stomach discomfort when you take this herb, taking it with food should prevent these unpleasant effects or at least make them less intense.

If you take this herb on an empty stomach, the short-term effects will kick in faster and they will be more pronounced but will not last as long.

Whether you take this herb in the morning or the evening typically does not make much difference. Both options are fine so feel free to experiment.

Where to buy saw palmetto?

Amazon is the best option for ordering saw palmetto and other herbal supplements in most countries. They offer some very affordable products backed by many positive reviews. Also, you can choose from a wide range of brands without having to search through other markets on the internet.

Some brands display the dosage per serving instead of per pill or capsule. Therefore, you may accidentally buy something less potent than you intended. Do not fall for this marketing trick.

FAQ

As with most other herbs and herbal supplements, it is best to cycle saw palmetto and stay off of it for about 2 days per week to reset your tolerance back to baseline. This will keep your body sensitive to the herb and allow you to keep getting the benefits in the long term.

When you take an extract standardized for fatty acids and sterols, you know exactly how potent it is and how much you need to take to get the desired outcome. Herbal extracts also tend to be cheaper than unextracted powders in many cases. However, many of the potentially beneficial compounds get lost during the extraction process. Therefore, if you know how potent the unextracted powder is, it is almost always a better option.

All of these options are fine. The two most important things to consider are the price and dosing. Powders are almost always the cheapest form. However, you may need a highly accurate scale to dose them correctly (preferably 0.001g). You can get one for as little as $20 from Amazon. Dosing the powders also takes some time that can add up over months or years. The disadvantage of capsules is that they are often made of bovine gelatine, which rarely comes from ethical sources.

Yes, you can. This herb should not impact your sleep in any negative way. Whether you take it in the morning or the evening typically doesn’t make much of a difference. Both options are fine so feel free to experiment.

This herb should not become harmful once it exceeds the expiration date but it can lose potency over time. Keep the herb or the herbal supplement in a cold, dark, and dry place, and it should remain just as potent for many months or even years.

As an adaptogen, saw palmetto acts as a mild stressor on the body. This is usually a great thing as it allows your body to adapt to specific forms of stress and become more resilient. However, putting too much stress on the body can be counter-productive and cause multiple side effects, including toxicity. While acute toxicity is extremely rare, taking very high amounts of this herb could lead to chronic toxicity and cause health problems over time. To prevent chronic toxicity or the buildup of tolerance, staying below 500 mg of saw palmetto a day is best unless you have a great reason to take more.

While you could safely take higher doses, there is no point in taking more than 500 mg of saw palmetto daily. This amount should give you all of the benefits without meaningful side effects. Paradoxically, taking a higher dose would likely lead to fewer benefits as the body would become accustomed to the herb.

The half-life of saw palmetto in the body is about 1.9 hours. This herb should be processed in your body within 8 hours after consuming it.

The effects of this herb are cumulative. Therefore, you must take it for at least 2-4 weeks to notice the benefits. But again, cycling the herb and not taking it at least twice a week is necessary to prevent tolerance in the long term.

Yes, saw palmetto is vegan-friendly. If you buy this herb in a capsulated form, beware that the capsules often contain animal-based gelatin. Instead, find a brand that puts its products into cellulose capsules.

No, it doesn’t. The herb does not interfere with fasting in any significant way.

References

Most of the information in this guide is based on scientific research that can be found and verified in the PubMed medical library. We highly encourage you to use the library to verify anything you read in this article. We excluded from consideration studies that are either confounded or have a high conflict of interest.