Is there a risk of cancer associated with melatonin (N-acetyl-5-methoxytryptamine) supplementation?

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Last updated: April 7, 2025View editorial policy

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From the Guidelines

Melatonin does not appear to increase cancer risk based on current evidence. The available data on melatonin's safety profile, as outlined in the 2015 clinical practice guideline for the treatment of intrinsic circadian rhythm sleep-wake disorders 1, does not suggest a link between melatonin use and an increased risk of cancer. This guideline, published in the Journal of Clinical Sleep Medicine, notes that melatonin is generally associated with a lack of reported serious adverse effects, although it does caution about the purity of available preparations and the reliability of stated doses.

When considering the potential risks and benefits of melatonin, particularly in relation to cancer, it's essential to weigh the evidence carefully. While there is limited research directly addressing the long-term effects of melatonin supplementation, the available studies, including a randomized, placebo-controlled trial and a meta-analysis reviewing controlled trials with melatonin, have not identified significant adverse effects that would suggest an increased cancer risk 1.

Key points to consider include:

  • Melatonin's safety profile, as reported in the guideline, indicates that short-term use of ≤ 10 mg/daily appears to be safe in healthy adults, although caution is advised in certain populations such as children, adolescents, and women of reproductive age.
  • The potential for melatonin to have protective effects against certain cancers, through mechanisms like antioxidant effects and inhibition of cancer cell growth, is an area of ongoing research.
  • As with any supplement, individuals, especially those with existing medical conditions or hormone-sensitive cancers, should consult healthcare providers before using melatonin regularly to ensure safe use and minimize potential risks.

Given the current state of evidence, the use of melatonin, when prescribed appropriately and at the lowest effective dose, does not appear to pose a significant risk of cancer. However, ongoing monitoring and research into the long-term effects of melatonin supplementation are necessary to fully understand its safety profile and potential benefits or risks in relation to cancer and other health outcomes 1.

From the Research

Risk of Cancer with Melatonin

  • There are no research papers provided that directly examine the risk of cancer with melatonin 2, 3, 4, 5, 6.
  • The studies provided focus on the treatment of insomnia in cancer patients using cognitive behavioral therapy for insomnia (CBT-I) and other interventions, but do not investigate the relationship between melatonin and cancer risk.
  • None of the studies mention melatonin as a potential risk factor for cancer or explore its effects on cancer development or progression.
  • As a result, it is not possible to draw conclusions about the risk of cancer with melatonin based on the provided evidence.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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