Drug & supplement interaction

Hydrazine Sulfate + Letrozole

Letrozole brand name: Femara.

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 Hydrazine Sulfate and Letrozole 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

Hydrazine Sulfate and Letrozole

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 Letrozole and Hydrazine Sulfate 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.

Hydrazine Sulfate safety at a glance

Hydrazine Sulfate overall Avoid Rigorous trials showed no benefit and it can cause serious harm.
Pregnancy Possibly Unsafe When used orally. Hydrazine sulfate has been linked to cases of significant adverse effects including hepatotoxicity, encephalopathy, and death. Read the full pregnancy detail
Breastfeeding Possibly Unsafe When used orally. Hydrazine sulfate has been linked to cases of significant adverse effects including hepatotoxicity, encephalopathy, and death. 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 Letrozole and Hydrazine Sulfate? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Letrozole

Interactions in our licensed database are recorded against drug classes, not just single drug names. Letrozole is filed under 4 classifications — including aromatase inhibitors, cytochrome p450 2c19 (cyp2c19) inhibitors, cytochrome p450 3a4 (cyp3a4) substrates. Hydrazine Sulfate has documented interactions with 3 drug classes — the most serious being antidiabetes drugs (moderate), isoniazid (moderate) and monoamine oxidase inhibitors (maois) (moderate) — and none of Letrozole’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

Hydrazine Sulfate Does Interact With Other Medications

Hydrazine Sulfate has 98 moderate known drug interactions in our database — Letrozole isn’t one of them. If you take anything else, check it against the full list below.

Moderate 98 No known interaction 2,732 (incl. Letrozole)
Taking anything else?

Check Another of Your Medications Against Hydrazine Sulfate

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

What to actually watch for

No Interaction Found — But Data Suggests Hydrazine Sulfate and Letrozole 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.

  • Bleeding or bruising Worth acting on Additional detail

    Hydrazine Sulfate

    “In one case report, a 55-year-old male with sinus carcinoma developed hepatorenal failure after self-treating with hydrazine sulfate 180 mg daily for approximately four months. Two weeks after discontinuing hydrazine sulfate, the patient presented to the emergency room with rash, pruritus, progressive malaise, and jaundice.”

    Hydrazine Sulfate · Natural Medicines adverse-effect record, reported in hepatic encephalopathy.

    1 source cited
    1. 10384. Hainer MI, Tsai N, Komura ST, Chiu CL. Fatal hepatorenal failure associated with hydrazine sulfate. Ann Intern Med 2000;133:877-80. PubMed

    Letrozole

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

  • Tiredness Additional detail

    Hydrazine Sulfate

    “Orally, hydrazine sulfate has been reported to cause paresthesia in the upper and lower extremities, tremors, lethargy/somnolence, confusion, convulsions, depression, headache, palpebral tic, slurred speech, hiccup, and vertigo.”

    Hydrazine Sulfate · Natural Medicines adverse-effect record, reported in cluster headache.

    6 sources cited
    1. 11767. Ochoa M Jr, Wittes RE, Krakoff IH. Trial of hydrazine sulfate (NSC-150014) in patients with cancer. Cancer Chemother Rep 1975;59:1151-4.
    2. 55782. Laszlo, J., Durant, J., and Loeb, V. Clinical pharmacologic study of 1-acetyl-2-picolinoyl hydrazine (NSC- 68626). Cancer Chemother Rep 1969;53(2):131-134.
    3. 55785. Reid, F. J. Hydrazine poisoning. Br Med J 11-20-1965;5472:1246.
    4. 55769. Wiernikowski, A. and Langer, D. [Acute poisoning with orally ingested hydrazine hydrate]. Polski Tygodnik Lekarski 7-21-1975;30(29):1231-1232.
    5. 55796. Filov, V. A., Gershanovich, M. L., Danova, L. A., and Ivin, B. A. Experience of the treatment with Sehydrin (Hydrazine Sulfate, HS) in the advanced cancer patients. Invest New Drugs 1995;13(1):89-97. PubMed
    6. 55764. Gershanovich, M. L., Danova, L. A., Kondratyev, V. B., Malyugina, L. L., Stukov, A. N., Seitz, J. F., and Filov, V. A. Clinical data on the antitumor activity of hydrazine sulfate. Cancer Treat.Rep. 1976;60(7):933-935.

    Letrozole

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

  • Dizziness Additional detail

    Hydrazine Sulfate

    “Hydrazine sulfate is generally considered unsafe for use. Any benefits of therapy may not outweigh the risk of toxicity.

    Most Common Adverse Effects:

    Orally: Blurred vision, confusion, dizziness, nausea, vomiting.

    Serious Adverse Effects (Rare):

    Orally: Encephalopathy, hepatorenal failure.”

    Hydrazine Sulfate · Natural Medicines adverse-effect record, reported in nausea and vomiting.

    Letrozole

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

  • Headache Additional detail

    Hydrazine Sulfate

    Recorded for Hydrazine Sulfate in the same Natural Medicines adverse-effect record shown under Tiredness above.

    Letrozole

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

  • Nausea Additional detail

    Hydrazine Sulfate

    “Orally, hydrazine sulfate has been reported to cause nausea and vomiting in numerous clinical studies. It has also been reported to cause anorexia, pyrosis, diarrhea, constipation, distorted taste, and hunger.”

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

    6 sources cited
    1. 55796. Filov, V. A., Gershanovich, M. L., Danova, L. A., and Ivin, B. A. Experience of the treatment with Sehydrin (Hydrazine Sulfate, HS) in the advanced cancer patients. Invest New Drugs 1995;13(1):89-97. PubMed
    2. 8004. Chlebowski RT, Bulcavage L, Grosvenor M, et al. Hydrazine sulfate in cancer patients with weight loss. A placebo-controlled clinical experience. Cancer 1987;59:406-10. PubMed
    3. 8005. Kaegi E. Unconventional therapies for cancer: 4. Hydrazine sulfate. Task Force on Alternative Therapies of the Canadian Breast Cancer Research Initiative. CMAJ 1998;158:1327-30.
    4. 55764. Gershanovich, M. L., Danova, L. A., Kondratyev, V. B., Malyugina, L. L., Stukov, A. N., Seitz, J. F., and Filov, V. A. Clinical data on the antitumor activity of hydrazine sulfate. Cancer Treat.Rep. 1976;60(7):933-935.
    5. 10385. Gershanovich ML, Danova LA, Ivin BA, Filov VA. Results of clinical study antitumor action of hydrazine sulfate. Nutr Cancer 1981;3:7-12..
    6. 11767. Ochoa M Jr, Wittes RE, Krakoff IH. Trial of hydrazine sulfate (NSC-150014) in patients with cancer. Cancer Chemother Rep 1975;59:1151-4.

    Letrozole

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

Reported for Hydrazine Sulfate but not commonly for Letrozole: blurred vision, kidney problems, constipation and low blood sugar.

Effects for Letrozole come from the ADVERSE REACTIONS section of its FDA label; effects for Hydrazine Sulfate 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

Hydrazine Sulfate in Pregnancy & Breastfeeding

Pregnancy And Lactation Possibly Unsafe

When used orally. Hydrazine sulfate has been linked to cases of significant adverse effects including hepatotoxicity, encephalopathy, and death.

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 Hydrazine Sulfate or Letrozole

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

This page covers Hydrazine Sulfate only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Letrozole page lists 142 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Grapefruit (major), St. John's Wort (major), 7-methoxyflavone (moderate) and Acacia Rigidula (moderate).

By severity: 3 major · 99 moderate · 40 minor.

From our pharmacist’s overview on the Letrozole page

“Letrozole (Femara) is prescribed to keep hormone-driven breast cancer from returning, so a supplement that shifts its blood level can quietly undercut treatment. Give this list of 142 ingredients genuine respect, and learn the three major entries first.”

Reviewed by 2 · Jul 18, 2026

Open the Letrozole interaction page

How much people look this up

Where Hydrazine Sulfate and Letrozole 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 Hydrazine Sulfate
Top half

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

29 days ago today
Medication Letrozole
Top 5%

#50 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 Hydrazine Sulfate reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Hydrazine Sulfate and Letrozole 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 Hydrazine Sulfate

What is Hydrazine Sulfate?

  • Cancer-related weight loss (cachexia)
  • Cancer treatment (unproven)
  • Appetite stimulation
  • Improving quality of life in advanced illness

Hydrazine sulfate is a synthetic industrial chemical that was promoted as an alternative cancer treatment, but well-designed clinical trials found it does not help people with cancer live longer or feel better. It carries real risks, including serious nerve and liver toxicity, and is not approved or recommended for any medical use. Talk with your doctor or pharmacist before considering it.

Not applicable (synthetic industrial chemical) · Capsules, tablets, oral solution, and injectable forms (not legally available as a supplement in the U.S.)

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

Hydrazine Sulfate: dosing

There is no safe or recommended dose of hydrazine sulfate, and it is not approved for medical use. Because it is not a legitimate supplement, no standardized, evidence-based dosing exists.We do not recommend taking it at all.

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

Read the full Hydrazine Sulfate monograph & all interactions
Medication

About Letrozole

What Is Letrozole Used For?

Brand name: Femara

Letrozole (brand name Femara) is used to treat breast cancer in postmenopausal women whose tumors are driven by estrogen. It is used in three settings: as adjuvant (after-surgery) treatment for hormone receptor positive early breast cancer; as extended adjuvant treatment for women who have already completed about five years of tamoxifen therapy; and as first- or second-line treatment for locally advanced or metastatic (spread) breast cancer.

Femara is specifically indicated for first-line treatment of hormone receptor positive or receptor-unknown locally advanced or metastatic breast cancer, and for advanced breast cancer in women whose disease has progressed after antiestrogen therapy.

See full Letrozole drug information
Keep checking

Other Drugs & Hydrazine Sulfate

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

0Major
98Moderate
0Minor
2,731No known interaction
98 Moderate 2,731 No interaction
Moderate

98 interactions

Showing 60 of 98 moderate interactions — see all 98 on the Hydrazine Sulfate page.

No interaction 2,731 drugs checked — show the list

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

Showing the 60 most looked-up of 2,731 medications checked with no known interaction — see the full Hydrazine Sulfate list.

See the full Hydrazine Sulfate interactions page
See every supplement checked against Letrozole, ranked by severity
Evidence & sources

Hydrazine Sulfate References

The 18 references that drive our Hydrazine Sulfate 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. Chlebowski RT, Bulcavage L, Grosvenor M, et al. Hydrazine sulfate in cancer patients with weight loss. A placebo-controlled clinical experience. Cancer 1987;59:406-10. PubMed
  2. Kaegi E. Unconventional therapies for cancer: 4. Hydrazine sulfate. Task Force on Alternative Therapies of the Canadian Breast Cancer Research Initiative. CMAJ 1998;158:1327-30.
  3. Hainer MI, Tsai N, Komura ST, Chiu CL. Fatal hepatorenal failure associated with hydrazine sulfate. Ann Intern Med 2000;133:877-80. PubMed
  4. Gershanovich ML, Danova LA, Ivin BA, Filov VA. Results of clinical study antitumor action of hydrazine sulfate. Nutr Cancer 1981;3:7-12..
  5. Ochoa M Jr, Wittes RE, Krakoff IH. Trial of hydrazine sulfate (NSC-150014) in patients with cancer. Cancer Chemother Rep 1975;59:1151-4.
  6. Sarich TC, Adams SP, Petricca G, Wright JM. Inhibition of isoniazid-induced hepatotoxicity in rabbits by pretreatment with an amidase inhibitor. J Pharmacol Exp Ther 1999;289:695-702. DOI
  7. Black M, Hussain H. Hydrazine, cancer, the Internet, isoniazid, and the liver. Ann Intern Med 2000;133:911-3. PubMed
  8. Gershanovich, M. L., Danova, L. A., Kondratyev, V. B., Malyugina, L. L., Stukov, A. N., Seitz, J. F., and Filov, V. A. Clinical data on the antitumor activity of hydrazine sulfate. Cancer Treat.Rep. 1976;60(7):933-935.
  9. Nagappan, R. and Riddell, T. Pyridoxine therapy in a patient with severe hydrazine sulfate toxicity. Crit Care Med. 2000;28(6):2116-2118. PubMed
  10. Wiernikowski, A. and Langer, D. [Acute poisoning with orally ingested hydrazine hydrate]. Polski Tygodnik Lekarski 7-21-1975;30(29):1231-1232.
  11. Gold, J. Use of hydrazine sulfate in terminal and preterminal cancer patients: results of investigational new drug (IND) study in 84 evaluable patients. Oncology 1975;32(1):1-10. PubMed
  12. Spremulli, E., Wampler, G. L., and Regelson, W. Clinical study of hydrazine sulfate in advanced cancer patients. Cancer Chemother.Pharmacol. 1979;3(2):121-124. PubMed
  13. Laszlo, J., Durant, J., and Loeb, V. Clinical pharmacologic study of 1-acetyl-2-picolinoyl hydrazine (NSC- 68626). Cancer Chemother Rep 1969;53(2):131-134.
  14. Freese, E., Sklarow, S., and Freese, E. B. DNA damage caused by antidepressant hydrazines and related drugs. Mutat.Res 1968;5(3):343-348. PubMed
  15. Reid, F. J. Hydrazine poisoning. Br Med J 11-20-1965;5472:1246.

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 Hydrazine Sulfate and Letrozole Together: Common Questions

Is it safe to take Hydrazine Sulfate with Letrozole?
We do not list a known interaction between Hydrazine Sulfate and Letrozole. 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 Hydrazine Sulfate and Letrozole 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 Hydrazine Sulfate and Letrozole combination checked?
Interactions in our licensed database are recorded against drug classes. Letrozole is filed under 4 classifications, and Hydrazine Sulfate has documented interactions with 3 drug classes — none of Letrozole'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 Hydrazine Sulfate interact with any other medications?
Yes. Hydrazine Sulfate has 98 documented drug interactions in our database — Letrozole 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 Letrozole interact with any supplements?
Yes. Letrozole has documented interactions with 142 supplements in our database — Hydrazine Sulfate is not one of them. The Letrozole 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

Hydrazine Sulfate monograph Uses, safety profile, and every drug interaction in one place Letrozole drug information The full plain-English guide to this medication Letrozole supplement interactions Every supplement checked against Letrozole, 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 18 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Letrozole and Hydrazine Sulfate?

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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.