Drug & supplement interaction

Black Currant + Granisetron

Granisetron brand names: Kytril, Sustol.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 20, 2026
The bottom line No known interaction

We found no known interaction between Black Currant 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

Black Currant 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 Black Currant 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.

Black Currant safety at a glance

Black Currant overall Use caution The berry is safe as a food, but concentrated supplements are less studied and should be used carefully.
Pregnancy Use caution Eating the berry in food amounts is likely fine, but supplements lack safety data, so check with your doctor first.
Breastfeeding Use caution Food amounts are probably okay, but there is not enough information on concentrated supplements, so use caution.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Granisetron and Black Currant? 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. Black Currant has documented interactions with 2 drug classes — the most serious being anticoagulant/antiplatelet drugs (moderate) and phenothiazines (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

Black Currant Does Interact With Other Medications

Black Currant has 140 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 140 No known interaction 2,690 (incl. Granisetron)
Taking anything else?

Check Another of Your Medications Against Black Currant

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

What to actually watch for

No Interaction Found — But Data Suggests Black Currant and Granisetron May Share a Side Effect

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.

  • Diarrhea Additional detail

    Black Currant

    “Of 2154 patients with hyperlipidemia taking black currant seed oil 1.8 grams twice daily for 6 weeks, 8 reports of mild diarrhea were considered related to the supplement. These adverse reactions were reported 2-10 days after beginning treatment with black currant seed oil.”

    Black Currant · Natural Medicines adverse-effect record, reported in diarrhea.

    1 source cited
    1. 17638. Fa-lin Z, Zhen-yu W, Yan H, et al. Efficacy of blackcurrant oil soft capsule, a Chinese herbal drug, in hyperlipidemia treatment. Phytother Res 2010;24 Suppl 2:S209-13. PubMed

    Granisetron

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

Effects for Granisetron come from the ADVERSE REACTIONS section of its FDA label; effects for Black Currant 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.

How to take them

Some Granisetron Products Have a Food Rule — Black Currant Should Not Break It

At least one FDA label for a product containing Granisetron says to take it on an empty stomach. Most supplements — Black Currant 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 Black Currant 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 Black Currant 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 Black Currant 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 Black Currant 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 Black Currant as Part of a Dietary Supplement Product? Check It for Interactions

We hold 1,265 real supplement products containing Black Currant, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Black Currant. Even though Black Currant 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 Black Currant 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 Black Currant
Top 25%

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

29 days ago today
Medication Granisetron
Steady interest

#2,677 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 Black Currant reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Black Currant 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 Black Currant

What is Black Currant?

Black Currant
  • Dry eyes and eye strain
  • Joint pain and inflammation
  • Immune and general wellness support
  • Cardiovascular health
  • Skin conditions (such as dry skin or eczema)

Black currant is a nutritious berry that is rich in vitamin C and antioxidants, and its seed oil contains the omega-6 fatty acid GLA. While it is enjoyed safely as a food and is popular as a supplement, solid human evidence for most health claims is still limited. Talk with your pharmacist or doctor before using concentrated supplements, especially if you are pregnant, nursing, or have a medical condition.

Ribes nigrum · Grossulariaceae · Berries (fruit), seeds (seed oil), and leaves · Whole berries, juice, capsules, seed oil softgels, dried leaf for tea, extracts

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

Black Currant: dosing

There is no official standardized dose for black currant supplements. The right amount can vary depending on the form (berry, juice, seed oil, or leaf) and the product's strength.Because doses are not well established, the safest approach is to follow the directions on the product label and not exceed them.

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

Read the full Black Currant 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 & Black Currant

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

0Major
140Moderate
0Minor
2,689No known interaction
140 Moderate 2,689 No interaction
Moderate

140 interactions

Showing 60 of 140 moderate interactions — see all 140 on the Black Currant page.

No interaction 2,689 drugs checked — show the list

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

Showing the 60 most looked-up of 2,689 medications checked with no known interaction — see the full Black Currant list.

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

Black Currant References

The 6 references that drive our Black Currant 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. Guivernau M, Meza N, Barja P, Roman O. Clinical and experimental study on the long-term effect of dietary gamma-linolenic acid on plasma lipids, platelet aggregation, thromboxane formation, and prostacyclin production. Prostaglandins Leukot Essent Fatty A PubMed
  2. Fa-lin Z, Zhen-yu W, Yan H, et al. Efficacy of blackcurrant oil soft capsule, a Chinese herbal drug, in hyperlipidemia treatment. Phytother Res 2010;24 Suppl 2:S209-13. PubMed
  3. Holman CP and Bell AF. A trial of evening primrose oil in the treatment of chronic schizophrenia. J Orhtomolecular Psych 1983;12:302-304.
  4. Vaddadi KS. The use of gamma-linolenic acid and linoleic acid to differentiate between temporal lobe epilepsy and schizophrenia. Prostaglandins Med 1981;6(4):375-379. PubMed
  5. Norred, C. L. and Brinker, F. Potential coagulation effects of preoperative complementary and alternative medicines. Alt Ther 2001;7(6):58-67.
  6. Puri BK. The safety of evening primrose oil in epilepsy. Prostaglandins Leukotrienes Essential Fatty Acids 2007;77:101-3. 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 Black Currant and Granisetron Together: Common Questions

Is it safe to take Black Currant with Granisetron?
We do not list a known interaction between Black Currant 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 Black Currant and Granisetron have any of the same side effects?
Yes — our sources link each of them separately to one 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 Black Currant 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 Black Currant 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 Black Currant and Granisetron combination checked?
Interactions in our licensed database are recorded against drug classes. Granisetron is filed under 3 classifications, and Black Currant has documented interactions with 2 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 Black Currant interact with any other medications?
Yes. Black Currant has 140 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 — Black Currant 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

Black Currant 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 6 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Granisetron and Black Currant?

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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.