Drug & supplement interaction

Tribulus + Granisetron

Granisetron brand names: Kytril, Sustol.

No Known Interaction

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Updated July 2026 · Pair last verified Sep 13, 2026

The bottom line No known interaction

We found no known interaction between Tribulus 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

Tribulus 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 Tribulus 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.

Tribulus safety at a glance

Tribulus overall Use caution Often well tolerated short-term in healthy adults, but quality and long-term safety data are limited.

Pregnancy Possibly Unsafe When used orally. Animal research suggests that tribulus might adversely affect fetal development; avoid using. Read the full pregnancy detail

Breastfeeding Avoid Avoid while breastfeeding due to a lack of reliable safety information.

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.

Still wondering about combining Granisetron and Tribulus? 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. Tribulus has documented interactions with 3 drug classes — the most serious being antidiabetes drugs (moderate), antihypertensive drugs (moderate) and lithium (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

Tribulus Does Interact With Other Medications

Tribulus has 259 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 259 No known interaction 2,571 (incl. Granisetron)

Taking anything else?

Check Another of Your Medications Against Tribulus

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

What to actually watch for

No Interaction Found — But Data Suggests Tribulus 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.

Trouble sleeping Additional detail
Tribulus
“Orally, tribulus has been reported to cause general excitation and insomnia. These symptoms were reversed upon discontinuation of the drug or decreasing the dose. In one case report, a patient drinking tribulus water 2 liters daily for two days presented with lower limb weakness, seizures, hepatitis, and acute kidney injury. The patient's condition improved after hemodialysis and discontinuation of tribulus water.”

Tribulus · Natural Medicines adverse-effect record, reported in epilepsy.
2 sources cited

78867. Tabakova, P., Dimitrov, M., Ognyanov, K., and et al. Clinical study of Tribestan in females with endocrine sterility. Documentation for Registration (unpublished) 1999.

92069. Talasaz AH, Abbasi MR, Abkhiz S, Dashti-Khavidaki S. Tribulus terrestris-induced severe nephrotoxicity in a young healthy male. Nephrol Dial Tranplant 2010;25(11):3792-3. PubMed
Granisetron

Listed in the ADVERSE REACTIONS section of the FDA label for Granisetron. Read the label on DailyMed ›
Constipation / Stomach pain / Diarrhea / Vomiting / Nausea Additional detail
Tribulus
“Orally, tribulus can cause abdominal pain, cramping, nausea, vomiting, diarrhea, and constipation. However, in one study, the rates of these gastrointestinal complaints were similar for patients taking tribulus and those receiving placebo.”

Tribulus · Natural Medicines adverse-effect record, reported in constipation.
2 sources cited

92022. Akhtari E, Raisi F, Keshavarz M, et al. Tribulus terrestris for treatment of sexual dysfunction in women: randomized double-blind placebo-controlled study. Daru 2014;22:40. PubMed

92027. Postigo S, Lima SM, Yamada SS, et al. Assessment of the effects of Tribulus terrestris on sexual function of menopausal women. Rev Bras Ginecol Obstet 2016;38(3):140-6. PubMed
Granisetron

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

Reported for Tribulus but not commonly for Granisetron: kidney problems, liver problems and seizures.

Effects for Granisetron come from the ADVERSE REACTIONS section of its FDA label; effects for Tribulus 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

Tribulus in Pregnancy & Breastfeeding

Pregnancy Possibly Unsafe

When used orally. Animal research suggests that tribulus might adversely affect fetal development; 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 — Tribulus Should Not Break It

At least one FDA label for a product containing Granisetron says to take it on an empty stomach. Most supplements — Tribulus 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 Tribulus 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.

Overlapping uses

What Granisetron Is Prescribed For, and What Tribulus Has Been Studied For

These two come up together because they touch the same health topic — not because they do the same job. Granisetron is a prescription medicine with approved uses on its FDA label. Tribulus is a supplement: what follows is what researchers have looked at it for, and how strong that evidence is.

Granisetron is prescribed for: 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.

Read the rest of what Granisetron is prescribed for

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.

Tribulus has been studied for:

Cancer studied, not established Tribulus has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

Tribulus for cancer

Although there is interest in using oral tribulus for cancer, there is insufficient reliable information about the clinical effects of tribulus for this condition.

Effectiveness ratings and the research summaries above are the verbatim record from the Natural Medicines database, which grades evidence from “Effective” down to “Insufficient Reliable Evidence To Rate”. A rating below the top of that scale means researchers have looked at it — not that it works, and never that it can stand in for a prescribed medicine. Do not stop or replace Granisetron on your own; if you are taking Tribulus for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

Everything else you take

See Every Supplement That Interacts With Granisetron

This page covers Tribulus 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 Tribulus as Part of a Dietary Supplement Product? Check It for Interactions

We hold 1,680 real supplement products containing Tribulus, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Tribulus. Even though Tribulus 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 Tribulus 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 Tribulus

Top 10%

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

29 days ago today

Medication Granisetron

Steady interest

#2,597 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 Tribulus reference on this page ↓
Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Tribulus and Granisetron records this page draws on were last updated July 11, 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 Dr. Brian Staiger, PharmD, BCPS.

Supplement

About Tribulus

What is Tribulus?

Low libido and sexual function
Athletic performance and muscle building
Testosterone support
Male and female fertility
General 'vitality' or wellness

Tribulus is a plant supplement most often marketed to boost libido, testosterone, and athletic performance, but the human evidence behind these claims is weak and inconsistent. It is generally well tolerated by healthy adults in the short term, but it should be avoided during pregnancy and breastfeeding and discussed with your pharmacist or doctor before use.

Tribulus terrestris · Zygophyllaceae · Fruit, leaf, and root · Capsules, tablets, powders, tinctures, and standardized extracts

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

Tribulus: dosing

There is no well-established standard dose for Tribulus. Studies have used a range of doses and different extracts, often standardized to a percentage of saponins, which makes it hard to compare products or recommend one amount.The best approach is to follow the directions on the specific product label and not exceed them.

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

Read the full Tribulus 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 & Tribulus

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

0Major

259Moderate

0Minor

2,570No known interaction

259 Moderate 2,570 No interaction

Moderate

259 interactions

Showing 60 of 259 moderate interactions — see all 259 on the Tribulus page.

No interaction 2,570 drugs checked — show the list

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

Showing the 60 most looked-up of 2,570 medications checked with no known interaction — see the full Tribulus list.

See the full Tribulus interactions page

See every supplement checked against Granisetron, ranked by severity

Evidence & sources

Tribulus References

The 10 references that drive our Tribulus 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.

Sharifi AM, Darabi R, Akbarloo N. Study of antihypertensive mechanism of Tribulus terrestris in 2K1C hypertensive rats: role of tissue ACE activity. Life Sci 2003;73:2963-71. PubMed
Walker D, Bird A, Flora T, O'Sullivan B. Some effects of feeding Tribulus terrestris, Ipomoea lonchophylla and the seed of Abelmoschus ficulneus on fetal development and the outcome of pregnancy in sheep. Reprod Fertil Dev 1992;4:135-44. PubMed
Al-Ali M, Wahbi S, Twaij H, Al-Badr A. Tribulus terrestris: preliminary study of its diuretic and contractile effects and comparison with Zea mays. J Ethnopharmacol 2003;85:257-60. PubMed
Tabakova, P., Dimitrov, M., Ognyanov, K., and et al. Clinical study of Tribestan in females with endocrine sterility. Documentation for Registration (unpublished) 1999.
Akhtari E, Raisi F, Keshavarz M, et al. Tribulus terrestris for treatment of sexual dysfunction in women: randomized double-blind placebo-controlled study. Daru 2014;22:40. PubMed
Ryan M, Lazar I, Nadasdy GM, et al. Acute kidney injury and hyperbilirubinemia in a young male after ingestion of Tribulus terrestris. Clin Nephrol 2015;83(3):177-83. PubMed
Postigo S, Lima SM, Yamada SS, et al. Assessment of the effects of Tribulus terrestris on sexual function of menopausal women. Rev Bras Ginecol Obstet 2016;38(3):140-6. PubMed
Talasaz AH, Abbasi MR, Abkhiz S, Dashti-Khavidaki S. Tribulus terrestris-induced severe nephrotoxicity in a young healthy male. Nephrol Dial Tranplant 2010;25(11):3792-3. PubMed
Samani NB, Jokar A, Soveid M, Heydari M, Mosavat SH. Efficacy of the hydroalcoholic extract of Tribulus terrestris on the serum glucose and lipid profile of women with diabetes mellitus: a double-blind randomized placebo-controlled clinical trial. J Evid
Siddiqui MA, Itrat M, Mobeen A, Khan MI. Efficacy of khar-i-khasak (Tribulus terrestris Linn.) in prehypertension: a randomized, double-blind, placebo-controlled trial. J Complement Integr Med. 2021.

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 Tribulus and Granisetron Together: Common Questions

Is it safe to take Tribulus with Granisetron?

We do not list a known interaction between Tribulus 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 Tribulus and Granisetron have any of the same side effects?

Yes — our sources link each of them separately to 6 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 Tribulus 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 Tribulus 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.

Are Tribulus and Granisetron used for the same thing?

They overlap in purpose, which usually means the real question is whether you need both rather than whether they are safe together. This page lists the shared uses and how strong the evidence is for Tribulus in each. That is a conversation for your prescriber, especially if Granisetron is being adjusted to a target.

How was the Tribulus and Granisetron combination checked?

Interactions in our licensed database are recorded against drug classes. Granisetron is filed under 3 classifications, and Tribulus 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 Tribulus interact with any other medications?

Yes. Tribulus has 259 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 — Tribulus 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

Tribulus 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 10 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Granisetron and Tribulus?

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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.