Drug & supplement interaction

Melatonin + Pazopanib

Pazopanib brand name: Votrient.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Pazopanib falls into 3 drug categories that Melatonin can interact with; the most serious is rated moderate. Theoretically, melatonin may have anticoagulant effects and may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions3
EvidenceB
What do Severity, Likelihood & Evidence mean?
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Interaction report

Melatonin and Pazopanib

These two interact in 3 distinct ways. Each one is explained separately below.

Why Are There 3 Interactions?

Melatonin interacts with whole categories of medication. Pazopanib falls into 3 of those categories, so it can interact with Melatonin in 3 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

ANTICOAGULANT/ANTIPLATELET DRUGS

1 of 3

Why this applies to Pazopanib

Pazopanib falls under ANTICOAGULANT/ANTIPLATELET DRUGS — the group Melatonin interacts with.

Theoretically, melatonin may have anticoagulant effects and may increase the risk of bleeding if used with anticoagulant or antiplatelet drugs.
There are isolated case reports of minor bleeding and decreased prothrombin activity in people taking melatonin with warfarin (Coumadin). The mechanism, if any, of this interaction is unknown. Taking melatonin orally seems to decrease coagulation activity within one hour of dosing in healthy men.
Severity Moderate Likelihood Possible Evidence B

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's something worth knowing about pairing melatonin with pazopanib (Votrient). Pazopanib itself can already raise your risk of bleeding, which is a recognized side effect of this kinase inhibitor. Melatonin, in theory, may slightly lower how well your blood clots. So the worry is that stacking the two could add up and make bleeding a bit more likely, showing up as things like easy bruising, nosebleeds, bleeding gums, or blood in your urine or stool.

I want to be honest about the evidence here: this is mostly theoretical, based on a few small reports (mostly with warfarin, not pazopanib), so it's far from certain. Still, because pazopanib carries its own bleeding risk, it's a smart conversation to have. Please check with your oncologist or pharmacist before adding melatonin.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Herxheimer A, Petrie KJ. Melatonin for the prevention and treatment of jet lag. Cochrane Database Syst Rev 2002;2:CD001520. PubMed
  2. Wirtz, P. H., Spillmann, M., Bartschi, C., Ehlert, U., and von Kanel, R. Oral melatonin reduces blood coagulation activity: a placebo-controlled study in healthy young men. J Pineal Res 2008;44(2):127-133. PubMed
  3. U.S.Food and Drug Administration. Special Nutritionals Adverse Events Monitoring System: registered case reports.
Moderate

IMMUNOSUPPRESSANTS

2 of 3

Pazopanib also falls under IMMUNOSUPPRESSANTS.

Theoretically, melatonin might interfere with immunosuppressive therapy.
Melatonin can stimulate immune function. Theoretically, melatonin might interfere with immunosuppressive therapy.
Severity Moderate Likelihood Possible Evidence B

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the idea behind this one. Pazopanib (Votrient) is a cancer medicine that works by slowing the growth of tumor cells. Melatonin, on the other hand, can gently nudge your immune system to be a bit more active. The concern is mostly theoretical: in some lab and lower-quality studies, melatonin's immune-stimulating effect could, in principle, work against a therapy meant to hold cancer growth in check.

I want to be straight with you: this is not a strong, well-proven interaction, and pazopanib is not the kind of immune-suppressing drug used for transplants. We just don't have solid human data here. Because you're dealing with a serious cancer treatment, please don't add melatonin on your own. Run it past your oncologist or pharmacist first so they can weigh it for your situation.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Lissoni P, Barni S, Mandala M, et al. Decreased toxicity and increased efficacy of cancer chemotherapy using the pineal hormone melatonin in metastatic solic tumor patients with poor clinical status. Eur J Cancer 1999;35:1688-92.
Minor

CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES

3 of 3

Pazopanib also falls under CYTOCHROME P450 3A4 (CYP3A4) SUBSTRATES.

Theoretically, melatonin might increase levels of drugs metabolized by CYP3A4.
Laboratory research shows that certain lots of melatonin inhibit CYP3A4. Theoretically, combined administration of melatonin with certain drugs metabolized by CYP3A4 may reduce the metabolism of these drugs, resulting in increased serum levels. Until more is known, use melatonin cautiously in patients taking drugs metabolized by these enzymes.
Severity Minor Likelihood Possible Evidence D

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the situation with these two. Pazopanib (Votrient) is cleared from your body mainly by a liver enzyme called CYP3A4. Some lab studies suggest melatonin might slow that enzyme down a bit. If that happened, your body would clear pazopanib a little slower, and the amount in your blood could creep up. With a cancer drug like this, higher levels could mean more of its known side effects, things like high blood pressure, fatigue, diarrhea, nausea, or changes on liver blood tests.

The honest part: this is only a theoretical concern based on test-tube research, not real patients, so I wouldn't lose sleep over it. Still, because pazopanib is a serious medication, please check with your oncologist or pharmacist before adding melatonin.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Foster BC, Cvijovic K, Boon HS, et al. Melatonin Interaction Resulting in Severe Sedation. J Pharm Pharm Sci 2015;18(2):124-31. PubMed

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Melatonin Also Interacts With Other Medications

Melatonin has 1,115 moderate, 345 minor known drug interactions in our database — the Pazopanib one above is among them. If you take anything else, check it against the full list below.

Moderate 1,115 Minor 345 No known interaction 1,370 (incl. Pazopanib)
Taking anything else?

Check Another of Your Medications Against Melatonin

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

From our Q&A

Questions About Melatonin or Pazopanib

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

This page covers Melatonin only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Pazopanib page lists 349 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), Arsenic (major), Asarabacca (major) and Beer (major).

By severity: 14 major · 297 moderate · 38 minor.

From our pharmacist’s overview on the Pazopanib page

“Take a careful look before mixing supplements with pazopanib (Votrient), an oral pill for advanced kidney cancer and certain sarcomas. Fourteen of the 349 ingredients on file are rated major, grapefruit among them, since it can raise pazopanib levels enough to intensify side effects.”

Reviewed by 2 · Jul 18, 2026

Open the Pazopanib interaction page

One more smart check

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

We hold 2,885 real supplement products containing Melatonin, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Melatonin. Your product may carry other ingredients that interact with Pazopanib too, on top of Melatonin — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Melatonin and Pazopanib 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 Melatonin
Top 5%

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

29 days ago today
Medication Pazopanib
Steady interest

#2,516 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.

Supplement

About Melatonin

What is Melatonin?

Melatonin
  • Trouble falling asleep (insomnia)
  • Jet lag
  • Delayed sleep phase syndrome
  • Non-24-hour sleep-wake disorder
  • Shift-work sleep problems
  • Sleep problems in some children with conditions like autism or ADHD

Melatonin is a hormone your body makes naturally to help control your sleep-wake cycle, and the supplement form is widely used to help with sleep timing problems and jet lag. The evidence is strongest for certain circadian (body-clock) disorders and is more mixed for everyday insomnia. It is generally well tolerated for short-term use, but talk with your pharmacist or doctor before starting, especially for children or during pregnancy.

Read the full Melatonin monograph & all interactions
Medication

About Pazopanib

What Is Pazopanib Used For?

Brand name: Votrient

Pazopanib tablets — sold as the brand Votrient and as generic pazopanib — are used to treat two types of advanced cancer in adults: advanced renal cell carcinoma (RCC), the most common form of kidney cancer, and advanced soft tissue sarcoma (STS) in patients who have already received prior chemotherapy.

Important limitation: Pazopanib has not been shown to work in adipocytic soft tissue sarcoma (a subtype involving fat cells) or in gastrointestinal stromal tumors (GISTs), so it is not used for those cancers.

See full Pazopanib drug information
Keep checking

Other Drugs & Melatonin

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

0Major
1,115Moderate
345Minor
1,369No known interaction
1,115 Moderate 345 Minor 1,369 No interaction
Moderate

1,115 interactions

Showing 60 of 1,115 moderate interactions — see all 1,115 on the Melatonin page.

Minor

345 interactions

Showing 60 of 345 minor interactions — see all 345 on the Melatonin page.

No interaction 1,369 drugs checked — show the list

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

Showing the 60 most looked-up of 1,369 medications checked with no known interaction — see the full Melatonin list.

See the full Melatonin interactions page
See every supplement checked against Pazopanib, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Melatonin monograph › Uses, safety, and every drug interaction in one place Pazopanib supplement interactions › Every supplement checked against Pazopanib, ranked by severity Pazopanib drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Melatonin and Pazopanib Together: Common Questions

Can you take Melatonin with Pazopanib?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
Why are there 3 interactions listed for Melatonin and Pazopanib?
Pazopanib belongs to more than one drug category, and Melatonin interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the Melatonin and Pazopanib interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

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

Still Have a Question About Pazopanib and Melatonin?

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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.