Melatonin for Cancer

Melatonin for Cancer: What It Is and How It May Help

Authors

Nancy Hepp, MS

past Lead Researcher

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Ms. Hepp is a researcher and communicator who has been writing and editing educational content on varied health topics for more than 20 years. She serves as lead researcher and writer for CancerChoices and also served as the first program manager. Her graduate work in research and cognitive psychology, her master’s degree in instructional design, and her certificate in web design have all guided her in writing and presenting information for a wide variety of audiences and uses. Nancy’s service as faculty development coordinator in the Department of Family Medicine at Wright State University also provided experience in medical research, plus insights into medical education and medical care from the professional’s perspective.

Nancy Hepp, MS past Lead Researcher

Sophie Kakarala

Research Assistant

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Sophie received her Bachelor of Arts from the University of Cambridge, where she studied Middle Eastern languages and the philosophy of science. She then completed a premedical post-baccalaureate at the City University of New York. Before joining CancerChoices, she worked for several years at the Cornell Center for Research on End-of-Life Care, where she helped to conduct research on terminal illness and grief. Working in end-of-life research filled her with the conviction that all patients deserve free, accessible, and scientifically accurate information about the therapies available to them. While taking classes in anthropology, she also became curious about traditional medical knowledge and philosophies. These interests led her to CancerChoices. She is delighted to be part of CancerChoices’s work creating rigorous, evidence-based treatment guides for patients and physicians.

Sophie Kakarala Research Assistant

Clinical reviewer

Dugald Seely, ND, MSc

Physician, researcher, and CancerChoices advisor

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Dugald Seely, ND, MSc is a naturopathic doctor and clinician scientist living in Ottawa, Canada. Dr. Seely serves patients living with cancer in clinic and is active in research building on the base of evidence for integrative and naturopathic oncology. Helping to pioneer the delivery and development of integrative oncology, Dr. Seely is the founder and executive director of The Centre for Health Innovation (CHI); an adjunct professor at the University of Ottawa, Faculty of Medicine; executive director for research and clinical epidemiology at the Canadian College of Naturopathic Medicine; and president of the Oncology Association of Naturopathic Physicians (OncANP). Dr. Seely has led numerous clinical trials and synthesis research over the past 18 years and has published and presented internationally. Dugald is the father of two and most happy when spending time with his family in the wild outdoors.

Dugald Seely, ND, MSc Physician, researcher, and CancerChoices advisor

Last update: July 22, 2026

Melatonin for cancer: what you need to know

• There is strong evidence that melatonin taken alongside conventional therapy may help improve cancer treatment survival and remission rates.
• There is modest evidence that melatonin can reduce a wide range of side effects, including depression, neurotoxicity, insomnia, and oral inflammation. It also appears to reduce overall inflammation.
• More research is needed about the right doses of melatonin in cancer treatment, and about whether melatonin supplements can reduce cancer risk. 
• This is not a standalone treatment for cancer; it is a complementary therapy used alongside standard medical care to support treatment and/or well-being.

What is melatonin?

Melatonin is a hormone your body naturally produces as part of your circadian rhythm, or sleep-wake cycle. It rises at night, promoting sleep, and may also reduce blood pressure and inflammation. It is available as an over-the-counter supplement, and is well-regarded as a treatment for disordered sleep.¹Howell M, Avidan AY et al. Management of REM sleep behavior disorder: an American Academy of Sleep Medicine clinical practice guideline. Journal of Clinical Sleep Medicine. 2023 Apr 1;19(4):759-768. There is strong evidence that taking supplemental melatonin can improve people’s response to treatment in solid-tumor cancers; in many studies, people who took melatonin during treatment saw longer survival and a higher rate of remission. There is some evidence that melatonin supplements can help with a wide range of side effects, including low platelet levels (thrombocytopenia), depression, and neurotoxicity; however, this evidence only rises to a modest level. Melatonin may also help reduce inflammation and oxidative DNA damage (both risk factors for cancer). 

There is an association between low natural melatonin levels and a higher risk of developing cancer. Since darkness is a cue for the body to produce melatonin, studies that investigate this connection suggest that avoiding disruptions to the circadian rhythm, like shift work or bright lights in the evening, could help reduce the risk of cancer by raising natural melatonin levels. However, it has not been shown that taking a melatonin supplement alone can counteract the risks of circadian rhythm disruption.

Of note, many of the clinical studies reviewed in this article involved unusually high doses of melatonin (up to 40mg nightly). The typical, safe dose of melatonin for an adult is 1-5mg daily. Therefore, it is best to interpret the results of these studies cautiously, and to consult your physician about what dose of melatonin is safe for you.

Safety

• Generally safe. Melatonin is widely used, though anyone taking medication or with a diagnosis of dementia should exercise caution.
• Contraindications: some studies suggest that melatonin can exacerbate autoimmune diseases. If you have an autoimmune condition like Crohn’s disease, rheumatoid arthritis, or type 1 diabetes, it is important to ask your physician whether it’s safe to take melatonin.
• Known interactions: consult with your doctor before adding to your regimen, particularly if you take a psychiatric medication, a blood pressure medication, or another medication for sleep. 
• Potential concerns with heart disease. 

See full safety details, side effects & drug interactions →

How melatonin may help people with cancer

Strength of evidence rating

We rate the strength of the evidence with 0=no evidence, 1=weak evidence, 2=modest evidence, and 3=good evidence. Read more about our method in detail here ›

Optimizing your body terrain

People without cancer treated with melatonin showed lower markers of inflammation across many studies.¹⁵Cho JH, Bhutani S, Kim CH, Irwin MR. Anti-inflammatory effects of melatonin: a systematic review and meta-analysis of clinical trials. Brain, Behavior, and Immunity. 2021 Mar;93:245-253; Zarezadeh M, Khorshidi M et al. Melatonin supplementation and pro-inflammatory mediators: a systematic review and meta-analysis of clinical trials. European Journal of Nutrition. 2020 Aug;59(5):1803-1813. There was also good evidence that people with and without cancer treated with melatonin experienced less oxidative damage to their DNA.¹⁶Ghorbaninejad P, Sheikhhossein F et al. Effects of melatonin supplementation on oxidative stress: a systematic review and meta-analysis of randomized controlled trials. Hormone Molecular Biology and Clinical Investigation. 2020 Nov 13;41(4); Morvaridzadeh M, Sadeghi E et al. Effect of melatonin supplementation on oxidative stress parameters: a systematic review and meta-analysis. Pharmacological Research. 2020 Nov;161:105210; Sookprasert A, Johns NP et al. Melatonin in patients with cancer receiving chemotherapy: a randomized, double-blind, placebo-controlled trial. Anticancer Research. 2014 Dec;34(12):7327-37; Elsabagh HH, Moussa E, Mahmoud SA, Elsaka RO, Abdelrahman H. Efficacy of melatonin in prevention of radiation-induced oral mucositis: a randomized clinical trial. Oral Diseases. 2020 Apr;26(3):566-572.

Reducing cancer risk or recurrence

Several observational studies have found that people with lower naturally-produced melatonin levels, particularly after menopause, were more likely to develop breast cancer¹⁷Veiga ECA, Simões R et al. Repercussions of melatonin on the risk of breast cancer: a systematic review and meta-analysis. Revista da Associação Médica Brasileira (1992). 2019 Jun 3;65(5):699-705; Xu J, Huang L, Sun GP. Urinary 6-sulfatoxymelatonin level and breast cancer risk: systematic review and meta-analysis. Scientific Reports. 2017 Jul 13;7(1):5353 and that people with higher melatonin levels were less likely to develop breast cancer.¹⁸Basler M, Jetter A et al. Urinary excretion of melatonin and association with breast cancer: meta-analysis and review of the literature. Breast Care (Basel). 2014 Jul;9(3):182-7; Yang WS, Deng Q, Fan WY, Wang WY, Wang X. Light exposure at night, sleep duration, melatonin, and breast cancer: a dose-response analysis of observational studies. European Journal of Cancer Prevention. 2014 Jul;23(4):269-76; Wang XS, Tipper S et al. First-morning urinary melatonin and breast cancer risk in the Guernsey Study. American Journal of Epidemiology. 2014 Mar 1;179(5):584-93. These studies suggest that higher natural levels of melatonin might help to protect against cancer, and suggest that lifestyle and environmental factors can play a role in cancer development by reducing nighttime melatonin. However, they do not prove that taking a melatonin supplement counteracts that risk. 

There is modest evidence that people treated with high doses of melatonin (20mg daily) after surgery may increase disease free survival in patients with advanced non-small cell lung cancer.¹⁹Seely D, Legacy M et al. Adjuvant melatonin for the prevention of recurrence and mortality following lung cancer resection (AMPLCaRe): a randomized placebo controlled clinical trial. EClinicalMedicine. 2021 Feb 27;33:100763.

See the full evidence summary ›

Affordability and access

Is a prescription required?

• No

Where to find it

• Melatonin is available over-the-counter at pharmacies

Affordability

• A one-month supply costs between $5 and 20 at most pharmacies and grocery stores

Find an integrative provider ›

FAQs

• Can melatonin help fight cancer?
  Yes: there is evidence that when taken alongside conventional cancer treatment for solid-tumor cancers, melatonin can help lengthen survival and increase the rate of remission. There is not yet evidence about whether it can help with blood cancers.
• Can melatonin help with fatigue during cancer treatment?
  The evidence is mixed about whether melatonin helps with fatigue.
• Can melatonin help with pain after surgery?
  There is modest evidence that melatonin can help to reduce pain after surgery. It also appears to help reduce anxiety before surgery in many people.
• Can melatonin reduce inflammation?
  Yes, there is good evidence that taking melatonin supplements can reduce overall inflammation.
• Can taking melatonin supplements prevent cancer?
  This has not been proven. There is good evidence that lower endogenous (produced by the body) melatonin levels are correlated with a higher risk of cancer, and vice versa. However, there is not evidence that taking a melatonin supplement can counteract this risk. Low melatonin levels can be due to many environmental factors, including night-shift work and bright lights at night, and taking a melatonin supplement may not counteract these risk factors.

Read more about supplements and therapies

• Sourcing Quality Herbs & Supplements ›
• Supplement and Therapies Database ›

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