Drug & supplement interaction

Gossypol + Phenytoin

Phenytoin brand names: Dilantin Kapseals, Dilantin, Di-Phen, Dilantin Infatabs, Phenytek, and others.

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 Gossypol and Phenytoin 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 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

Gossypol and Phenytoin

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 Phenytoin and Gossypol 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.

Gossypol safety at a glance

Gossypol overall Avoid Gossypol is toxic and is not approved as a safe dietary supplement.
Pregnancy Likely Unsafe When used orally; gossypol seems to have abortifacient and uterine stimulant effects, avoid using. Read the full pregnancy detail
Breastfeeding Possibly Unsafe When used orally; 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 Phenytoin and Gossypol? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Phenytoin

Interactions in our licensed database are recorded against drug classes, not just single drug names. Phenytoin is filed under 14 classifications — including cytochrome p450 2c8 (cyp2c8) substrates, cytochrome p450 2c9 (cyp2c9) inducers, anticonvulsants. Gossypol has documented interactions with 4 drug classes — the most serious being digoxin (lanoxin) (moderate), diuretic drugs (moderate) and stimulant laxatives (moderate) — and none of Phenytoin’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

Gossypol Does Interact With Other Medications

Gossypol has 104 moderate known drug interactions in our database — Phenytoin isn’t one of them. If you take anything else, check it against the full list below.

Moderate 104 No known interaction 2,726 (incl. Phenytoin)
Taking anything else?

Check Another of Your Medications Against Gossypol

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

What to actually watch for

No Interaction Found — But Data Suggests Gossypol and Phenytoin 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. 2 of them are worth acting on rather than waiting out — marked below.

  • A low platelet count Worth acting on Additional detail

    Gossypol

    “Orally, two cases of mild thrombocytopenia have been reported after taking high doses of gossypol.”

    Gossypol · Natural Medicines adverse-effect record, reported in thrombocytopenia.

    1 source cited
    1. 52616. Bushunow, P., Reidenberg, M. M., Wasenko, J., Winfield, J., Lorenzo, B., Lemke, S., Himpler, B., Corona, R., and Coyle, T. Gossypol treatment of recurrent adult malignant gliomas. J.Neurooncol. 1999;43(1):79-86. PubMed

    Phenytoin

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

  • Liver problems Worth acting on Additional detail

    Gossypol

    “Orally, gossypol seems to be well-tolerated when used at doses below 20 mg daily, short-term. Using gossypol long-term or in doses greater than 20 mg daily may be unsafe.

    Most Common Adverse Effects:

    Orally: Diarrhea, hypokalemia, nausea, and vomiting.

    Serious Adverse Effects (Rare):

    Orally: When used long-term or in high doses, circulatory problems, dermatologic toxicity, heart failure, hepatotoxicity, infertility (…”

    Gossypol · Natural Medicines adverse-effect record, reported in congestive heart failure (chf).

    Phenytoin

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

  • A change in taste Additional detail

    Gossypol

    “Orally, gossypol has been reported to cause nausea in 30% of subjects, vomiting in 15% of subjects, and diarrhea in 10% of subjects in one clinical study. High doses may cause mucosal sloughing, mucosal necrosis, and intestinal hemorrhage. Gossypol has also been reported to cause anorexia, malnutrition, and altered taste sensation.”

    Gossypol · Natural Medicines adverse-effect record, reported in anorexia.

    6 sources cited
    1. 52634. Van Poznak, C., Seidman, A. D., Reidenberg, M. M., Moasser, M. M., Sklarin, N., Van Zee, K., Borgen, P., Gollub, M., Bacotti, D., Yao, T. J., Bloch, R., Ligueros, M., Sonenberg, M., Norton, L., and Hudis, C. Oral gossypol in the treatment of patients wit
    2. 166. Miller LG. Herbal Medicinals: Selected clinical considerations focusing on known or potential drug-herb interactions. Arch Intern Med 1998;158:2200-11.
    3. 8290. Coutinho EM, Athayde C, Atta G, et al. Gossypol blood levels and inhibition of spermatogenesis in men taking gossypol as a contraceptive. A multicenter, international, dose-finding study. Contraception 2000;61:61-7. PubMed
    4. 52824. Aitken, R. J., Liu, J., Best, F. S., and Richardson, D. W. An analysis of the direct effects of gossypol on human spermatozoa. Int.J.Androl 1983;6(2):157-167. PubMed
    5. 8292. Herve JC, Pluciennik F, Bastide B, et al. Contraceptive gossypol blocks cell-to-cell communication in human and rat cells. Eur J Pharmacol 1996;313:243-55. PubMed
    6. 52665. Randel, R. D., Chase, C. C., Jr., and Wyse, S. J. Effects of gossypol and cottonseed products on reproduction of mammals. J.Anim Sci. 1992;70(5):1628-1638. PubMed

    Phenytoin

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

  • Vomiting / Nausea Additional detail

    Gossypol

    Recorded for Gossypol in the same Natural Medicines adverse-effect record shown under Liver problems above.

    Phenytoin

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

Reported for Gossypol but not commonly for Phenytoin: reduced appetite, heart failure, low potassium and bleeding or bruising.

Effects for Phenytoin come from the ADVERSE REACTIONS section of its FDA label; effects for Gossypol 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

Gossypol in Pregnancy & Breastfeeding

Pregnancy Likely Unsafe

When used orally; gossypol seems to have abortifacient and uterine stimulant effects, avoid using.

Lactation Possibly Unsafe

When used orally; 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

From our Q&A

Questions About Gossypol or Phenytoin

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Gossypol or Phenytoin, 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 Phenytoin

This page covers Gossypol only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Phenytoin page lists 224 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: 1,4-butanediol (major), Activated Charcoal (major), Beer (major), Gamma-hydroxybutyrate (ghb) (major) and Kava (major).

By severity: 9 major · 187 moderate · 28 minor.

From our pharmacist’s overview on the Phenytoin page

“Phenytoin (Dilantin) is a seizure medicine with a narrow therapeutic index, meaning small changes in its blood level can bring seizures back or tip over into toxicity, so I treat its supplement list with real seriousness. The biggest group, 78 ingredients, piles on sedation, and alcohol, kava, and GHB all rate major for exactly that re…”

Reviewed by 2 · Jul 18, 2026

Open the Phenytoin interaction page

How much people look this up

Where Gossypol and Phenytoin 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 Gossypol
Steady interest

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

29 days ago today
Medication Phenytoin
Top 25%

#687 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 Gossypol reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Gossypol and Phenytoin 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 Gossypol

What is Gossypol?

Gossypol
  • Male contraception (research interest)
  • Reduction of sperm production
  • Endometriosis (historical/research)
  • Antiviral and antiparasitic research
  • Cancer cell research

Gossypol is a toxic yellow pigment from cotton plants that has been studied mainly as an experimental male contraceptive because it can lower sperm production. It is not an approved or safe over-the-counter supplement, and it carries serious risks including possibly permanent infertility, low potassium, and organ toxicity. It should not be used for self-treatment.

Gossypium hirsutum · Malvaceae · Seeds (cottonseed) and seed oil; the pigment gossypol is extracted from these · Purified compound used in research; not commonly sold as a standardized consumer supplement

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

Gossypol: dosing

There is no established safe or standardized dose of gossypol for supplement use. The doses studied in research were used under medical supervision and still carried serious risks.Because gossypol is toxic and not approved as a dietary supplement, we cannot recommend any specific amount. If you encounter a product that lists gossypol, do not use it without first speaking to a pharmacist or doctor, and follow any professional guidance rather than a product label alone.

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

Read the full Gossypol monograph & all interactions
Medication

About Phenytoin

What Is Phenytoin Used For?

Brand names: Dilantin Kapseals, Dilantin, Di-Phen, Dilantin Infatabs, Phenytek, Dilantin injection

Phenytoin is used to treat and prevent seizures. The specific types covered depend on the formulation. Oral extended-release capsules (including Phenytek), chewable tablets (including Dilantin Infatabs and Phenytoin Infatabs), and oral suspension (including Dilantin-125) are used for tonic-clonic (grand mal) and psychomotor (temporal lobe) seizures; most oral forms also cover prevention and treatment of seizures occurring during or after neurosurgery. Chewable tablets and some capsule formulations also cover complex partial seizures.

Parenteral (injectable) phenytoin sodium is used for generalized tonic-clonic status epilepticus (a prolonged, life-threatening seizure emergency) and for prevention and treatment of seizures during neurosurgery. The IV form can also substitute short-term for oral phenytoin when a patient cannot take it by mouth.

Most-Reported Side Effects for Phenytoin

From FAERS, the FDA’s public side-effect reporting system (40,278 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Convulsion 3,522 reports
Seizure 3,095 reports
Toxicity to various agents 1,888 reports
Fall 1,604 reports
Dizziness 1,539 reports
See full Phenytoin drug information
Keep checking

Other Drugs & Gossypol

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

0Major
104Moderate
0Minor
2,725No known interaction
104 Moderate 2,725 No interaction
Moderate

104 interactions

Showing 60 of 104 moderate interactions — see all 104 on the Gossypol page.

No interaction 2,725 drugs checked — show the list

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

Showing the 60 most looked-up of 2,725 medications checked with no known interaction — see the full Gossypol list.

See the full Gossypol interactions page
See every supplement checked against Phenytoin, ranked by severity
Evidence & sources

Gossypol References

The 53 references that drive our Gossypol 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. The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.
  2. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
  3. Miller LG. Herbal Medicinals: Selected clinical considerations focusing on known or potential drug-herb interactions. Arch Intern Med 1998;158:2200-11.
  4. Cowart CL, London SN, Vernon MW, Pedigo NG. The effects of cyclic adenosine monophosphate, forskolin, and theophylline on motility parameters in gossypol-treated human sperm. Fertil Steril 1994;61:929-34. PubMed
  5. Coutinho EM. Gossypol: a contraceptive for men. Contraception 2002;65:259-63. PubMed
  6. Guo J, Reidenberg MM. Inhibition of 11beta-hydroxysteroid dehydrogenase by bioflavonoids and their interaction with furosemide and gossypol. J Lab Clin Med 1998;132:32-8.
  7. Coutinho EM, Athayde C, Atta G, et al. Gossypol blood levels and inhibition of spermatogenesis in men taking gossypol as a contraceptive. A multicenter, international, dose-finding study. Contraception 2000;61:61-7. PubMed
  8. Herve JC, Pluciennik F, Bastide B, et al. Contraceptive gossypol blocks cell-to-cell communication in human and rat cells. Eur J Pharmacol 1996;313:243-55. PubMed
  9. Taylor GT, Griffin MG, Bardgett M. Search for a male contraceptive: the effect of gossypol on sexual motivation and epididymal sperm. J Med 1991;22:29-44.
  10. Woolley, R. J. Contraception--a look forward, Part II: Mifepristone and gossypol. J.Am.Board Fam.Pract. 1991;4(2):103-113.
  11. Liu, G. Z., Lyle, K. C., and Cao, J. Clinical trial of gossypol as a male contraceptive drug. Part I. Efficacy study. Fertil.Steril. 1987;48(3):459-461. PubMed
  12. Qian, S. Z. and Wang, Z. G. Gossypol: a potential antifertility agent for males. Annu.Rev.Pharmacol.Toxicol. 1984;24:329-360. PubMed
  13. Qian, S. Z., Jing, G. W., Wu, X. Y., Xu, Y., Li, Y. Q., and Zhou, Z. H. Gossypol related hypokalemia. Clinicopharmacologic studies. Chin Med.J.(Engl.) 1980;93(7):477-482.
  14. Flack, M. R., Pyle, R. G., Mullen, N. M., Lorenzo, B., Wu, Y. W., Knazek, R. A., Nisula, B. C., and Reidenberg, M. M. Oral gossypol in the treatment of metastatic adrenal cancer. J.Clin.Endocrinol.Metab 1993;76(4):1019-1024. PubMed
  15. Bushunow, P., Reidenberg, M. M., Wasenko, J., Winfield, J., Lorenzo, B., Lemke, S., Himpler, B., Corona, R., and Coyle, T. Gossypol treatment of recurrent adult malignant gliomas. J.Neurooncol. 1999;43(1):79-86. 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 Gossypol and Phenytoin Together: Common Questions

Is it safe to take Gossypol with Phenytoin?
We do not list a known interaction between Gossypol and Phenytoin. 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 Gossypol and Phenytoin have any of the same side effects?
Yes — our sources link each of them separately to 5 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.
How was the Gossypol and Phenytoin combination checked?
Interactions in our licensed database are recorded against drug classes. Phenytoin is filed under 14 classifications, and Gossypol has documented interactions with 4 drug classes — none of Phenytoin'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 Gossypol interact with any other medications?
Yes. Gossypol has 104 documented drug interactions in our database — Phenytoin 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 Phenytoin interact with any supplements?
Yes. Phenytoin has documented interactions with 224 supplements in our database — Gossypol is not one of them. The Phenytoin 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

Gossypol monograph Uses, safety profile, and every drug interaction in one place Phenytoin drug information The full plain-English guide to this medication Phenytoin supplement interactions Every supplement checked against Phenytoin, 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 53 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Phenytoin and Gossypol?

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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.