Low-dose Naltrexone for Cancer

Low-dose Naltrexone for Cancer: Safety & Side Effects

This page covers safety information for Low-dose Naltrexone. See our complete Low-dose Naltrexone therapy guide →

Authors

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

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

Clinical reviewer

Laura Pole, MSN, RN, OCNS

Senior Clinical Consultant

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Laura Pole is senior clinical consultant for CancerChoices. Laura is an oncology clinical nurse specialist who has been providing integrative oncology clinical care, navigation, consultation, and education services for over 40 years. She is the co-creator and co-coordinator of the Integrative Oncology Navigation Training at Smith Center for Healing and the Arts in Washington, DC. Laura also manages the “Media Watch Cancer News That You Can Use” listserv for Smith Center/Commonweal. In her role as a palliative care educator and consultant, Laura has served as statewide Respecting Choices Faculty for the Virginia POST (Physician Orders for Scope of Treatment) Collaborative as well as provided statewide professional education on palliative and end-of-life care for the Virginia Association for Hospices and Palliative Care.

For CancerChoices, Laura curates content and research, networks with clinical and organizational partners, brings awareness and education of integrative oncology at professional and patient conferences and programs, and translates research into information relevant to the patient experience as well as clinical practice.

Laura sees her work with CancerChoices as a perfect alignment of all her passions, knowledge and skills in integrative oncology care. She is honored to serve you.

Laura Pole, MSN, RN, OCNS Senior Clinical Consultant

Last update: June 22, 2026

Is low-dose naltrexone safe?

Naltrexone is generally safe. However, its effect on cancer is not straightforward: while many preclinical (animal or lab) studies suggest that naltrexone could help fight cancer, animals treated with naltrexone developed more aggressive cancer in at least two studies.¹Kuramochi T, Sano M et al. Effects of tramadol via a µ-opioid receptor on pancreatic ductal adenocarcinoma in vitro and in vivo. Regional Anesthesia and Pain Medicine. 2024 Mar 4;49(3):200-208; Szymaszkiewicz A, Mierzejewski M et al. The role of bidirectional communication between the adipokines and the endogenous opioid system in an experimental mouse model of colitis-associated colorectal cancer. Pharmacology Reports. 2024 Feb;76(1):112-126. 

Side effects and adverse reactions

Naltrexone appears to be at least as safe as a placebo treatment.²Bolton M, Hodkinson A et al. Serious adverse events reported in placebo randomised controlled trials of oral naltrexone: a systematic review and meta-analysis. BMC Medicine. 2019 Jan 15;17(1):10.

Typical side effects include:³Elsegood L. Ed. The LDN Book. Vermont: Chelsea Green Publishing. 2016. p. 20; Bihari B. LDN and cancer. Low Dose Naltrexone. Feb 21, 2021. Viewed September 19, 2021.

• Difficulty sleeping, nightmares and vivid dreams
• Transitory stomach cramps and diarrhea
• Headache during the initial phase
• Agitation or dizziness, or involuntary movements (infrequent)
• Constipation and/or diarrhea: Infrequent, and more common among people with IBS, IBD, and/or Crohn’s disease
• Elevated liver enzymes 
• Reductions in renal function (rare)

Contraindications

Warnings from Low Dose Naltrexone:⁴Bihari B. LDN and cancer. Low Dose Naltrexone. Feb 21, 2021. Viewed September 19, 2021.

• Because LDN blocks opioid receptors throughout the body, people using opioid medication should not take LDN. LDN users preparing for surgery should generally discontinue LDN for one or two days prior to the surgery. After surgery, opioid-based medications are often used for pain management, so people should not restart LDN until cleared by their physician.
• Naltrexone can cause liver problems among people with liver disease. 
• People who have received organ transplants and who therefore are taking immunosuppressive medication should not take LDN because it could counter the effect of those medications, which could be potentially lethal.
• Caution is needed among people taking thyroid hormone replacement for a diagnosis of Hashimoto’s thyroiditis with low thyroid function (hypothyroidism) because LDN may affect thyroid function.

Drug interactions 

There are known drug interactions with this therapy, including with opioid medication. Interactions with medications and other interventions are complex. Always consult with a healthcare professional before adding any new therapy to your regimen. To learn more about interactions visit one of the trusted resources below: 

• About Herbs ›
• EfficaSafe ›

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