Drug & supplement interaction

Gossypol + Hydroxyurea

Hydroxyurea brand names: Droxia, Hydrea, Siklos, Xromi.

No Known Interaction
The bottom line No known interaction

We found no known interaction between Gossypol and Hydroxyurea 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 Hydroxyurea

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 Hydroxyurea 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 Hydroxyurea and Gossypol? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Hydroxyurea

Interactions in our licensed database are recorded against drug classes, not just single drug names. Hydroxyurea is filed under 2 classifications — antineoplastics, oral drugs. 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 Hydroxyurea’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 — Hydroxyurea isn’t one of them. If you take anything else, check it against the full list below.

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 Hydroxyurea 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. One of them is 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

    Hydroxyurea

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

  • Changes to your period Additional detail

    Gossypol

    “Orally, gossypol-mediated damage to the testes and a reversible reduction in testicular volume has been reported. Long-term use of gossypol has also been reported to cause long-term, and potentially permanent, infertility in males.”

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

    6 sources cited
    1. 52697. Zhong, C. Q., Lui, Q. L., Tang, Y. J., Wang, Y., Shi, F. J., and Qian, S. Z. Study on sperm function in men long after cessation of gossypol treatment. Contraception 1990;41(6):617-622. PubMed
    2. 52771. Kjaergaard, N. [Male contraception]. Ugeskr.Laeger 9-8-1986;148(37):2335-2338.
    3. 52746. Wu, D. F., Yu, Y. W., and Zheng, D. K. [Determination of (+)- and (-)-gossypol in human plasma using high performance liquid chromatography with pre-column chemical derivatization]. Yao Xue.Xue.Bao. 1988;23(12):927-932.
    4. 52745. Wu, D. F., Reidenberg, M. M., and Drayer, D. E. Determination of gossypol enantiomers in plasma after administration of racemate using high-performance liquid chromatography with precolumn chemical derivatisation. J.Chromatogr. 12-9-1988;433:141-148. PubMed
    5. 5914. Coutinho EM. Gossypol: a contraceptive for men. Contraception 2002;65:259-63. PubMed
    6. 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

    Hydroxyurea

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

  • Tiredness reported in 7.4% of FDA reports for Hydroxyurea Additional detail

    Gossypol

    “Orally, several studies have found a limited association between gossypol use and fatigue, while another study found no correlation.”

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

    5 sources cited
    1. 52819. Liu, G. Z. Clinical study of gossypol as a male contraceptive. Reproduccion. 1981;5(3):189-193.
    2. 52749. Coutinho, E. M. and Melo, J. F. Clinical experience with gossypol in non-Chinese men: a follow-up. Contraception 1988;37(2):137-151. PubMed
    3. 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
    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. 46316. 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

    Hydroxyurea

    Listed in the ADVERSE REACTIONS section of the FDA label for Hydroxyurea, and in voluntary FDA adverse-event reports. Read the label on DailyMed ›

  • Diarrhea / Nausea / Vomiting reported in 6.7% of FDA reports for Hydroxyurea 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

    Hydroxyurea

    Listed in the ADVERSE REACTIONS section of the FDA label for Hydroxyurea, and in voluntary FDA adverse-event reports. Read the label on DailyMed ›

Reported for Gossypol but not commonly for Hydroxyurea: reduced appetite, liver problems, a change in taste and heart failure.

Effects for Hydroxyurea come from the ADVERSE REACTIONS section of its FDA label; effects for Gossypol come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 21,027 voluntary FDA FAERS reports for Hydroxyurea 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

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

Overlapping uses

What Hydroxyurea Is Prescribed For, and What Gossypol Has Been Studied For

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

Hydroxyurea is prescribed for: Hydroxyurea is used for several serious conditions. Droxia, Siklos, and Xromi are each indicated to reduce the frequency of painful crises and reduce the need for blood transfusions in patients with sickle cell anemia who have recurrent moderate to severe painful crises. Siklos is approved for adults and children 2 years and older; Xromi is approved for children 6 months and older; Droxia is approved for adults. Hydrea capsules and Hydroxyurea capsules are indicated for resistant chronic myeloid leukemia and for locally advanced squamous cell carcinomas of the head and neck (excluding the lip) when used together with chemoradiation.

Gossypol has been studied for:

  • Head and neck cancer studied, not established Gossypol has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

    Gossypol for head and neck cancer

    It is unclear if oral gossypol is beneficial in patients with head and neck cancer.

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 Hydroxyurea on your own; if you are taking Gossypol for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

From our Q&A

Questions About Gossypol or Hydroxyurea

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 Hydroxyurea, 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 Hydroxyurea

This page covers Gossypol only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Hydroxyurea page lists 18 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Coffee Charcoal (moderate), European Mandrake (moderate), Glucomannan (moderate) and Guar Gum (moderate).

By severity: 1 major · 7 moderate · 10 minor.

From our pharmacist’s overview on the Hydroxyurea page

“People take hydroxyurea (Droxia, Hydrea, Siklos, Xromi) for serious reasons, most often sickle cell disease or certain blood cancers, and it only works if a steady dose reaches the bloodstream. That is exactly what nearly all 18 supplements listed here can undermine, so this page earns real vigilance rather than a skim.”

Reviewed by 2 · Jul 18, 2026

Open the Hydroxyurea interaction page

How much people look this up

Where Gossypol and Hydroxyurea 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
Top 25%

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

29 days ago today
Medication Hydroxyurea
Top 5%

#40 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 13, 2026. The Gossypol and Hydroxyurea 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 Hydroxyurea

What Is Hydroxyurea Used For?

Brand names: Droxia, Hydrea, Siklos, Xromi

Hydroxyurea is used for several serious conditions. Droxia, Siklos, and Xromi are each indicated to reduce the frequency of painful crises and reduce the need for blood transfusions in patients with sickle cell anemia who have recurrent moderate to severe painful crises. Siklos is approved for adults and children 2 years and older; Xromi is approved for children 6 months and older; Droxia is approved for adults.

Hydrea capsules and Hydroxyurea capsules are indicated for resistant chronic myeloid leukemia and for locally advanced squamous cell carcinomas of the head and neck (excluding the lip) when used together with chemoradiation.

Most-Reported Side Effects for Hydroxyurea

From FAERS, the FDA’s public side-effect reporting system (21,027 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Fatigue 1,548 reports
Sickle cell anaemia with crisis 1,486 reports
Diarrhea 1,408 reports
Nausea 1,306 reports
Headache 1,068 reports
See full Hydroxyurea 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
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
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 Hydroxyurea Together: Common Questions

Is it safe to take Gossypol with Hydroxyurea?
We do not list a known interaction between Gossypol and Hydroxyurea. 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 Hydroxyurea 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.
Are Gossypol and Hydroxyurea 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 Gossypol in each. That is a conversation for your prescriber, especially if Hydroxyurea is being adjusted to a target.
How was the Gossypol and Hydroxyurea combination checked?
Interactions in our licensed database are recorded against drug classes. Hydroxyurea is filed under 2 classifications, and Gossypol has documented interactions with 4 drug classes — none of Hydroxyurea'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 — Hydroxyurea 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 Hydroxyurea interact with any supplements?
Yes. Hydroxyurea has documented interactions with 18 supplements in our database — Gossypol is not one of them. The Hydroxyurea interaction page linked on this page lists every one, ranked by severity.

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

Still Have a Question About Hydroxyurea 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.