Drug & supplement interaction

Croton Seeds + Nivolumab

Nivolumab brand name: Opdivo.

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 Croton Seeds and Nivolumab 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 Nivolumab 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

Croton Seeds and Nivolumab

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 Nivolumab and Croton Seeds 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.

Worth understanding: our licensed dataset holds no drug-interaction record for Croton Seeds at all — not against Nivolumab, and not against any other medication we track. This verdict therefore rests on the absence of any recorded data, not on research that looked at this combination and found nothing. We cannot rule an interaction out.

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.

Croton Seeds safety at a glance

Croton Seeds overall Avoid Croton seeds and croton oil are toxic and can cause severe, sometimes fatal poisoning.
Pregnancy Avoid Avoid completely; croton is a strong purgative and irritant that may harm pregnancy.
Breastfeeding Unsafe When used orally. Croton seed oil has abortifacient properties; 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.

Still wondering about combining Nivolumab and Croton Seeds? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
What to actually watch for

No Interaction Found — But Data Suggests Croton Seeds and Nivolumab 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.

  • Itching Additional detail

    Croton Seeds

    “Orally, croton seeds can cause burning of the mouth, vomiting, dizziness, stupor, painful bowel movements, and collapse (18). Topically, croton seed oil can cause itching, burning and blistering of the skin (18).”

    Croton Seeds · Natural Medicines adverse-effect record, reported in nausea and vomiting.

    1 source cited
    1. 18. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.

    “Topically, croton seed oil can cause itching, burning and blistering when applied to the skin (18).”

    Croton Seeds · Natural Medicines adverse-effect record, reported in pruritus.

    1 source cited
    1. 18. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.

    Nivolumab

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

  • Dizziness Additional detail

    Croton Seeds

    “Orally, croton seed oil can cause dizziness, stupor, and collapse (18).”

    Croton Seeds · Natural Medicines adverse-effect record, reported in vertigo.

    1 source cited
    1. 18. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.

    Nivolumab

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

  • Vomiting Additional detail

    Croton Seeds

    “Orally, croton seeds and the seed oil can cause burning of the mouth, vomiting, and painful bowel movements (18).”

    Croton Seeds · Natural Medicines adverse-effect record, reported in nausea and vomiting.

    1 source cited
    1. 18. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.

    Nivolumab

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

Effects for Nivolumab come from the ADVERSE REACTIONS section of its FDA label; effects for Croton Seeds come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 96,645 voluntary FDA FAERS reports for Nivolumab that mention that effect — a reporting proportion, not an incidence rate and not evidence the drug caused it. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Special populations

Croton Seeds in Pregnancy & Breastfeeding

Lactation Unsafe

When used orally. Croton seed oil has abortifacient properties; 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 Nivolumab Products Have a Food Rule — Croton Seeds Should Not Break It

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

Table 2: Recommended Dosages of Intravenous OPDIVO in Combination with Other Therapeutic Agents Indication Recommended OPDIVO Dosage Duration of Therapy Unresectable or metastatic melanoma 1 mg/kg every 3 weeks with ipilimumab 3 mg/kg In combination with ipilimumab for a maximum of 4 doses or until unacceptable toxicity, whichever occurs earlier Adult patients and pediatric patients aged 12 years

From the Dosage and Administration section of the FDA label we read for Nivolumab — 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.

Everything else you take

See Every Supplement That Interacts With Nivolumab

This page covers Croton Seeds only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Nivolumab page lists 1 supplement it has a documented interaction with, worst first, each one explained.

The most serious there right now: American Pawpaw (minor).

By severity: 1 minor.

From our pharmacist’s overview on the Nivolumab page

“Nivolumab (Opdivo) is an immunotherapy infusion that trains the body's own immune system to recognize and attack cancer cells, the kind of drug you might expect to carry a long list of supplement warnings. It does not.”

Reviewed by 2 · Jul 18, 2026

Open the Nivolumab interaction page

One more smart check

Taking Croton Seeds as Part of a Dietary Supplement Product? Check It for Interactions

We hold 6 real supplement products containing Croton Seeds, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Croton Seeds. Even though Croton Seeds itself has no known interaction with Nivolumab, 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 Croton Seeds and Nivolumab 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 Croton Seeds
Top half

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

29 days ago today
Medication Nivolumab
Steady interest

#2,132 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 Croton Seeds reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Croton Seeds and Nivolumab 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 .
Supplement

About Croton Seeds

What is Croton Seeds?

  • Severe constipation (traditional purgative)
  • Digestive complaints
  • Skin conditions (topical, traditional)
  • Traditional Chinese and folk medicine remedies

Croton seeds and croton oil come from Croton tiglium, a plant historically used as a powerful purgative, but they are highly toxic and can be dangerous or even deadly. Because of the serious risk of poisoning, severe irritation, and burns, croton seeds are not recommended for self-use. If you are considering any product containing croton, talk to a doctor or pharmacist first.

Croton tiglium · Euphorbiaceae · Seeds and the oil pressed from the seeds (croton oil) · Croton oil, processed seeds, and traditional herbal preparations (rarely available as a standard supplement)

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

Croton Seeds: dosing

There is no safe, standardized dose of croton seeds or croton oil for self-care, and we will not suggest an amount. The difference between a traditional 'dose' and a poisonous amount is very small, which is part of why croton is considered so dangerous.We do not recommend taking croton seeds.

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

Read the full Croton Seeds monograph & all interactions
Medication

About Nivolumab Injection

What Is Nivolumab Injection Used For?

Brand name: Opdivo

Opdivo (nivolumab) is used to treat many types of cancer in adults, and some in patients 12 years and older. It can be used alone or in combination with other therapies depending on the cancer type and stage. Cancers it treats include melanoma (including after surgery to reduce the chance of the cancer coming back), non-small cell lung cancer, malignant pleural mesothelioma, advanced renal cell carcinoma (kidney cancer), classical Hodgkin lymphoma, squamous cell carcinoma of the head and neck, urothelial carcinoma (bladder cancer), colorectal cancer with specific genetic features (MSI-H or dMMR), hepatocellular carcinoma (liver cancer), esophageal cancer, gastroesophageal junction cancer, and gastric (stomach) cancer.

Some uses require the tumor to test positive for a protein called PD-L1, and some are specific to certain stages of disease or prior treatments received. Your oncologist will determine which use applies to your situation.

Most-Reported Side Effects for Nivolumab

From FAERS, the FDA’s public side-effect reporting system (96,645 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Malignant neoplasm progression 9,878 reports
Diarrhea 5,251 reports
Fatigue 4,195 reports
Fever 3,721 reports
Nausea 3,182 reports
See full Nivolumab Injection drug information
Keep checking

Other Drugs & Croton Seeds

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

0Major
0Moderate
0Minor
2,829No known interaction
2,829 No interaction
No interaction 2,829 drugs checked — show the list

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

Showing the 60 most looked-up of 2,829 medications checked with no known interaction — see the full Croton Seeds list.

See the full Croton Seeds interactions page
See every supplement checked against Nivolumab, ranked by severity
Evidence & sources

Croton Seeds References

The 2 references that drive our Croton Seeds 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. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
  2. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.

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 Croton Seeds and Nivolumab Together: Common Questions

Is it safe to take Croton Seeds with Nivolumab?
We do not list a known interaction between Croton Seeds and Nivolumab. 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 Croton Seeds and Nivolumab have any of the same side effects?
Yes — our sources link each of them separately to 3 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 Croton Seeds and Nivolumab at the same time of day?
At least one FDA label for a product containing Nivolumab 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 Nivolumab on its own and move Croton Seeds 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.
Does Nivolumab interact with any supplements?
Yes. Nivolumab has documented interactions with 1 supplement in our database — Croton Seeds is not one of them. The Nivolumab 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

Croton Seeds monograph Uses, safety profile, and every drug interaction in one place Nivolumab Injection drug information The full plain-English guide to this medication Nivolumab supplement interactions Every supplement checked against Nivolumab, 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 2 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Nivolumab and Croton Seeds?

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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.