Drug & supplement interaction

Saw Palmetto + Granisetron

Granisetron brand names: Kytril, Sustol.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 13, 2026
The bottom line No known interaction

We found no known interaction between Saw Palmetto and Granisetron in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first. Additionally, although there is no interaction, the label for Granisetron states a food rule worth keeping to, and the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Saw Palmetto and Granisetron

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Granisetron and Saw Palmetto in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Saw Palmetto safety at a glance

Saw Palmetto overall Use caution Generally well tolerated in adults but should be used under guidance, especially for prostate or urinary symptoms.
Pregnancy Likely Unsafe When used orally. Saw palmetto has hormonal activity; avoid using. Read the full pregnancy detail
Breastfeeding Likely Unsafe When used orally. Saw palmetto has hormonal activity; avoid using. Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Pharmacist analysis

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On the whole, saw palmetto has very few reported drug interactions due to its lack of effects on liver metabolizing enzymes (e.g., CYP P450 enzymes).

There have been some reports of minor interactions with anticoagulants, estrogens, and contraceptives due to saw palmetto's purported effects on blood clotting and various hormones in the body. However, these interactions have generally only been seen in lab studies and for most individuals, are not considered clinically significant.

As always, however, be sure to talk to your doctor before starting any new medications or supplements so you can be appropriately monitored.

Comprehensive analysis does not indicate a significant interaction.

—

Still wondering about combining Granisetron and Saw Palmetto? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Granisetron

Interactions in our licensed database are recorded against drug classes, not just single drug names. Granisetron is filed under 3 classifications — serotonergic drugs, serotonergic drugs, oral drugs. Saw Palmetto has documented interactions with 3 drug classes — the most serious being anticoagulant/antiplatelet drugs (moderate), contraceptive drugs (moderate) and estrogens (moderate) — and none of Granisetron’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Saw Palmetto Does Interact With Other Medications

Saw Palmetto has 174 moderate known drug interactions in our database — Granisetron isn’t one of them. If you take anything else, check it against the full list below.

Moderate 174 No known interaction 2,656 (incl. Granisetron)
Taking anything else?

Check Another of Your Medications Against Saw Palmetto

Covers the 2,830 medications we’ve checked against Saw Palmetto. Pick one to open its full report.

What to actually watch for

No Interaction Found — But Data Suggests Saw Palmetto and Granisetron May Share Several of the Same Side Effects

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do. 4 of them are worth acting on rather than waiting out — marked below.

  • A slow heartbeat / An irregular heartbeat / Raised blood pressure Worth acting on Additional detail

    Saw Palmetto

    “Occasionally, cases of hypertension, postural hypotension, tachycardia, angina pectoris, arrhythmia, extrasystole, angiopathy, myocardial infarction, and congestive heart failure have been reported in patients using saw palmetto orally. One case of severe bradycardia and second degree heart block was reported in a 64 year-old male taking an unknown amount of saw palmetto for a few weeks.”

    Saw Palmetto · Natural Medicines adverse-effect record, reported in angina.

    1 source cited
    1. 96413. Jipescu D, Patel A, Bohra H, Pientka A. Rare case of saw palmetto induced heart block. JACC 2017;69(11) supplement:2310.

    Granisetron

    Listed in the ADVERSE REACTIONS section of the FDA label for Granisetron. Read the label on DailyMed ›

  • Shortness of breath Worth acting on Additional detail

    Saw Palmetto

    “Rhinitis is one of the more commonly reported adverse effects of saw palmetto. One patient taking saw palmetto extract 160 mg twice daily reported "breathlessness". Two cases of respiratory depression have been reported in patients using saw palmetto extract (Permixon) 320 mg.”

    Saw Palmetto · Natural Medicines adverse-effect record, reported in depression.

    3 sources cited
    1. 73348. Agbabiaka, T. B., Pittler, M. H., Wider, B., and Ernst, E. Serenoa repens (saw palmetto): a systematic review of adverse events. Drug Saf 2009;32(8):637-647. PubMed
    2. 73388. Braeckman J. The extract of Serenoa repens in the treatment of benign prostatic hyperplasia: a multicenter open study. Current Therapeutic Research 1994;55(7):776-785. DOI
    3. 6772. Stepanov VN, Siniakova LA, Sarrazin B, Raynaud JP. Efficacy and tolerability of the lipidosterolic extract of Serenoa repens (Permixon) in benign prostatic hyperplasia: a double-blind comparison of two dosage regimens. Adv Ther 1999;16:231-41.

    Granisetron

    Listed in the ADVERSE REACTIONS section of the FDA label for Granisetron. Read the label on DailyMed ›

  • A fast or pounding heartbeat / Low blood pressure Additional detail

    Saw Palmetto

    Recorded for Saw Palmetto in the same Natural Medicines adverse-effect record shown under A slow heartbeat / An irregular heartbeat / Raised blood pressure above.

    Granisetron

    Listed in the ADVERSE REACTIONS section of the FDA label for Granisetron. Read the label on DailyMed ›

  • Trouble sleeping Additional detail

    Saw Palmetto

    “Orally, saw palmetto can cause headaches, dizziness, insomnia, and fatigue.”

    Saw Palmetto · Natural Medicines adverse-effect record, reported in fatigue.

    Granisetron

    Listed in the ADVERSE REACTIONS section of the FDA label for Granisetron. Read the label on DailyMed ›

  • Constipation Additional detail

    Saw Palmetto

    “Gastrointestinal complaints such as nausea, vomiting, constipation, diarrhea, gastralgia, and halitosis are the most frequently reported adverse effects associated with saw palmetto. Less often, cases of duodenal ulcer, dyspepsia, or heartburn have been reported. Meteorism (intestinal gas accumulation) has also been reported with saw palmetto, although causality was unclear.”

    Saw Palmetto · Natural Medicines adverse-effect record, reported in constipation.

    4 sources cited
    1. 6772. Stepanov VN, Siniakova LA, Sarrazin B, Raynaud JP. Efficacy and tolerability of the lipidosterolic extract of Serenoa repens (Permixon) in benign prostatic hyperplasia: a double-blind comparison of two dosage regimens. Adv Ther 1999;16:231-41.
    2. 73329. Aliaev, IuG, Vinarov, A. Z., Lokshin, K. L., and Spivak, L. G. [Efficiency and safety of prostamol-Uno in patients with chronic abacterial prostatitis]. Urologiia. 2006;(1):47-50.
    3. 73354. Mantovani, F. Serenoa repens in benign prostatic hypertrophy: analysis of 2 Italian studies. Minerva Urol.Nefrol. 2010;62(4):335-340.
    4. 60442. Morgia, G., Mucciardi, G., Gali, A., Madonia, M., Marchese, F., Di, Benedetto A., Romano, G., Bonvissuto, G., Castelli, T., Macchione, L., and Magno, C. Treatment of chronic prostatitis/chronic pelvic pain syndrome category IIIA with Serenoa repens plus

    Granisetron

    Listed in the ADVERSE REACTIONS section of the FDA label for Granisetron. Read the label on DailyMed ›

  • Stomach pain Additional detail

    Saw Palmetto

    Recorded for Saw Palmetto in the same Natural Medicines adverse-effect record shown under Constipation above.

    Granisetron

    Listed in the ADVERSE REACTIONS section of the FDA label for Granisetron. Read the label on DailyMed ›

  • Tiredness Additional detail

    Saw Palmetto

    “Orally, saw palmetto may cause fatigue, weakness, muscle pain, and back pain, although these adverse events are rare. A case of saw palmetto-related rhabdomyolysis was reported in an 82-year-old male presenting with kidney dysfunction, increased C-reactive protein levels, and elevated serum creatine kinase.”

    Saw Palmetto · Natural Medicines adverse-effect record, reported in back pain.

    1 source cited
    1. 73358. Hanaka, M., Yoshii, C., Yatera, K., Ito, C., Chojin, Y., Nagata, S., Yamasaki, K., Nishida, C., Kawanami, T., Kawanami, Y., Ishimoto, H., and Mukae, H. [A case of rhabdomyolysis caused by saw palmetto of healthy foods]. J.UOEH. 6-1-2012;34(2):193-199. PubMed

    Granisetron

    Listed in the ADVERSE REACTIONS section of the FDA label for Granisetron. Read the label on DailyMed ›

Showing the 10 most notable of 14 shared effects — ranked by how unusual each one is, not just whether both lists mention it.

Reported for Saw Palmetto but not commonly for Granisetron: heart failure, a heart attack, erection problems and a change in sex drive.

Effects for Granisetron come from the ADVERSE REACTIONS section of its FDA label; effects for Saw Palmetto come from the Natural Medicines adverse-effect record, quoted above. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Special populations

Saw Palmetto in Pregnancy & Breastfeeding

Pregnancy And Lactation Likely Unsafe

When used orally. Saw palmetto has hormonal activity; avoid using.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.© 2026 Therapeutic Research Center

How to take them

Some Granisetron Products Have a Food Rule — Saw Palmetto Should Not Break It

At least one FDA label for a product containing Granisetron says to take it on an empty stomach. Most supplements — Saw Palmetto included — are taken with a meal, so the easy mistake is swallowing both together at breakfast. Where that rule applies, keep Granisetron on its own and move Saw Palmetto to a meal later in the day.

This may not be true of your version. Food instructions belong to the product, not the ingredient: two Granisetron products can carry different directions, and extended-release forms often differ from immediate-release ones. The label we read is quoted below — check the directions on your own box or bottle, or ask your pharmacist, for how to take the exact product you were given.

Recommended Dosage ( 2.2 ): The recommended dosage in adults is 10 mg administered as a single subcutaneous injection at least 30 minutes before the start of emetogenic chemotherapy on Day 1.

From the Dosage and Administration section of the FDA label we read for Granisetron — where that label names a specific product, the instruction is that product's. Read the label on DailyMed ›

A food rule is not an interaction — it is about how much of the medicine you absorb. The directions that came with your own product, and your pharmacist, outrank anything on this page.

From our Q&A

Questions About Saw Palmetto or Granisetron

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Saw Palmetto or Granisetron, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Granisetron

This page covers Saw Palmetto only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Granisetron page lists 38 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Lithium (major), 5-htp (moderate), Acetyl-l-carnitine (moderate) and Ayahuasca (moderate).

By severity: 2 major · 25 moderate · 11 minor.

From our pharmacist’s overview on the Granisetron page

“Granisetron (Kytril, Sustol) blocks serotonin signals to stop nausea from chemotherapy and surgery, and this is a list that warrants real caution before you add a supplement to it. Most of the entries raise serotonin themselves, and stacking them on a serotonin-acting drug can push toward serotonin syndrome, a dangerous overload of tha…”

Reviewed by 2 · Jul 18, 2026

Open the Granisetron interaction page

One more smart check

Taking Saw Palmetto as Part of a Dietary Supplement Product? Check It for Interactions

We hold 3,466 real supplement products containing Saw Palmetto, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Saw Palmetto. Even though Saw Palmetto itself has no known interaction with Granisetron, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Saw Palmetto and Granisetron Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Saw Palmetto
Top 10%

#77 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Granisetron
Steady interest

#2,603 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Saw Palmetto reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Saw Palmetto and Granisetron records this page draws on were last updated July 10, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
Supplement

About Saw Palmetto

What is Saw Palmetto?

Saw Palmetto
  • Benign prostatic hyperplasia (BPH) symptoms
  • Urinary problems
  • Hair loss
  • Prostate health
  • Inflammation

Saw palmetto is a plant extract most often used for urinary symptoms linked to an enlarged prostate (BPH). The best research suggests it works no better than a placebo for most men, though it is generally well tolerated. Talk to your doctor or pharmacist before using it, especially for prostate or urinary problems that need proper evaluation.

Serenoa repens · Arecaceae · Fruit (berries) · Capsules, softgels, tablets, liquid extracts, dried berries, tea

An interaction check asks whether these two react with each other — it does not ask whether Saw Palmetto is a good idea for someone in your situation. Here is what our Saw Palmetto record says about it on its own.

Saw Palmetto: dosing

There is no official, agreed-upon dose for saw palmetto. Products vary in strength and how they are prepared, and many are standardized to a certain percentage of fatty acids.The safest approach is to follow the dosing directions on the product label and not exceed them. They can help you decide whether it is appropriate and what dose is reasonable for you.

From our Saw Palmetto monograph — the full record covers uses, side effects and every documented interaction.

Read the full Saw Palmetto monograph & all interactions
Medication

About Granisetron

What Is Granisetron Used For?

Brand names: Kytril, Sustol

Granisetron is used to prevent nausea and vomiting linked to emetogenic (nausea-causing) cancer chemotherapy — including high-dose cisplatin — and radiation therapy, including total body irradiation and fractionated abdominal radiation. Granisetron hydrochloride tablets and Granisol oral solution are approved for both the chemotherapy and radiation indications. Sancuso skin patch is approved for prevention of nausea and vomiting in adults receiving moderately and/or highly emetogenic chemotherapy regimens of up to 5 consecutive days.

Granisetron hydrochloride injection (intravenous) is also used to prevent and treat postoperative nausea and vomiting in adults. Sustol (subcutaneous injection) is used in combination with other anti-nausea medicines in adults specifically for the prevention of acute and delayed nausea and vomiting associated with moderately emetogenic chemotherapy or anthracycline and cyclophosphamide combination chemotherapy regimens.

See full Granisetron drug information
Keep checking

Other Drugs & Saw Palmetto

Browse every other medication we’ve checked against Saw Palmetto — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
174Moderate
0Minor
2,655No known interaction
174 Moderate 2,655 No interaction
Moderate

174 interactions

Showing 60 of 174 moderate interactions — see all 174 on the Saw Palmetto page.

No interaction 2,655 drugs checked — show the list

We also checked Saw Palmetto against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,655 medications checked with no known interaction — see the full Saw Palmetto list.

See the full Saw Palmetto interactions page
See every supplement checked against Granisetron, ranked by severity
Evidence & sources

Saw Palmetto References

The 22 references that drive our Saw Palmetto monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Wilt TJ, Ishani A, Stark G, et al. Saw palmetto extracts for treatment of benign prostatic hyperplasia: a systematic review. JAMA 1998;280:1604-9. PubMed
  2. Carraro JC, Raynaud JP, Koch G, et al. Comparison of phytotherapy (Permixon) with finasteride in the treatment of benign prostate hyperplasia: a randomized international study of 1,098 patients. Prostate 1996;29:231-40. DOI
  3. Di Silverio F, D'Eramo G, Lubrano C, et al. Evidence that Serenoa repens extract displays an antiestrogenic activity in prostatic tissue of benign prostatic hypertrophy patients. Eur Urol 1992;21:309-14. PubMed
  4. Stepanov VN, Siniakova LA, Sarrazin B, Raynaud JP. Efficacy and tolerability of the lipidosterolic extract of Serenoa repens (Permixon) in benign prostatic hyperplasia: a double-blind comparison of two dosage regimens. Adv Ther 1999;16:231-41.
  5. Cheema P, El-Mefty O, Jazieh AR. Intraoperative haemorrhage associated with the use of extract of Saw Palmetto herb: a case report and review of literature. J Intern Med 2001;250:167-9. PubMed
  6. Jibrin I, Erinle A, Saidi A, Aliyu ZY. Saw palmetto-induced pancreatitis. South Med J 2006;99:611-2. PubMed
  7. 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. Avins AL, Bent S, Staccone S, et al. A detailed safety assessment of a saw palmetto extract. Complement Ther Med 2008;16:147-54. PubMed
  9. Morgia, G., Mucciardi, G., Gali, A., Madonia, M., Marchese, F., Di, Benedetto A., Romano, G., Bonvissuto, G., Castelli, T., Macchione, L., and Magno, C. Treatment of chronic prostatitis/chronic pelvic pain syndrome category IIIA with Serenoa repens plus
  10. Aliaev, IuG, Vinarov, A. Z., Lokshin, K. L., and Spivak, L. G. [Efficiency and safety of prostamol-Uno in patients with chronic abacterial prostatitis]. Urologiia. 2006;(1):47-50.
  11. Agbabiaka, T. B., Pittler, M. H., Wider, B., and Ernst, E. Serenoa repens (saw palmetto): a systematic review of adverse events. Drug Saf 2009;32(8):637-647. PubMed
  12. Wargo, K. A., Allman, E., and Ibrahim, F. A possible case of saw palmetto-induced pancreatitis. South.Med.J. 2010;103(7):683-685. PubMed
  13. Lapi, F., Gallo, E., Giocaliere, E., Vietri, M., Baronti, R., Pieraccini, G., Tafi, A., Menniti-Ippolito, F., Mugelli, A., Firenzuoli, F., and Vannacci, A. Acute liver damage due to Serenoa repens: a case report. Br.J.Clin.Pharmacol. 2010;69(5):558-560.
  14. Mantovani, F. Serenoa repens in benign prostatic hypertrophy: analysis of 2 Italian studies. Minerva Urol.Nefrol. 2010;62(4):335-340.
  15. Hanaka, M., Yoshii, C., Yatera, K., Ito, C., Chojin, Y., Nagata, S., Yamasaki, K., Nishida, C., Kawanami, T., Kawanami, Y., Ishimoto, H., and Mukae, H. [A case of rhabdomyolysis caused by saw palmetto of healthy foods]. J.UOEH. 6-1-2012;34(2):193-199. PubMed

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Saw Palmetto and Granisetron Together: Common Questions

Is it safe to take Saw Palmetto with Granisetron?
We do not list a known interaction between Saw Palmetto and Granisetron. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
Do Saw Palmetto and Granisetron have any of the same side effects?
Yes — our sources link each of them separately to 10 of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
Should I take Saw Palmetto and Granisetron at the same time of day?
At least one FDA label for a product containing Granisetron says to take it on an empty stomach, and supplements are usually taken with a meal — so taking them together at breakfast is the easy mistake. Where that applies, keep Granisetron on its own and move Saw Palmetto to a meal later in the day. Food instructions belong to the product rather than the ingredient, so check the directions on your own box. This is about absorption, not an interaction.
How was the Saw Palmetto and Granisetron combination checked?
Interactions in our licensed database are recorded against drug classes. Granisetron is filed under 3 classifications, and Saw Palmetto has documented interactions with 3 drug classes — none of Granisetron's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Saw Palmetto interact with any other medications?
Yes. Saw Palmetto has 174 documented drug interactions in our database — Granisetron is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Granisetron interact with any supplements?
Yes. Granisetron has documented interactions with 38 supplements in our database — Saw Palmetto is not one of them. The Granisetron interaction page linked on this page lists every one, ranked by severity.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Where next

Keep Exploring

Saw Palmetto monograph Uses, safety profile, and every drug interaction in one place Granisetron drug information The full plain-English guide to this medication Granisetron supplement interactions Every supplement checked against Granisetron, ranked by severity Supplement interaction checker Check any supplement or product against your medications Browse medications A–Z Every drug we’ve checked against herbs & supplements References The 22 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Granisetron and Saw Palmetto?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.