Cimetidine and Other H2 Blockers
H2 blockers, used to treat gastrointestinal ulcers and/or reduce stomach acid, may improve survival among people with cancer, especially after colorectal cancer resection.
Cimetidine and other H2 blockers at a glance
Cimetidine and other histamine H2-receptor antagonists, also known as H2 blockers, are used to treat gastrointestinal ulcers and/or reduce stomach acid. They are available both as over-the-counter medications for heartburn and stomach acid and as prescription drugs. Their use in treating cancer is considered off-label.
Some research, mostly small studies, show better cancer survival when people are treated with cimetidine, often around the time of surgery or along with other conventional treatmentsthe cancer care offered by conventionally trained physicians and most hospitals; examples are chemotherapy, surgery, and radiotherapy. The strongest evidence relates to colorectal cancer. Use may also reduce risk of lung cancer, although use of ranitidine—but not other H2 blockers—is linked to higher risk of one type of breast cancer, and people with diabetes have shown a higher risk of lung cancer when using H2 blockers.
CancerChoices ratings for H2 blockers
We rate cimetidine and other H2 blockers on seven attributes, with 0 the lowest rating and 5 the highest. We rate the strength of the evidence supporting the use of cimetidine or other H2 blockers for a medical benefit, such as improving treatment outcomes or managing side effects.
See how we evaluate and rate complementary therapies ›
Improving treatment outcomes
See More- Modest evidencesignificant effects in at least three small but well-designed randomized controlled trials (RCTs), or one or more well-designed, mid-sized clinical studies of reasonably good quality (RCTs or observational studies), or several small studies aggregated into a meta-analysis (this is the CancerChoices definition; other researchers and studies may define this differently) of better survival after surgical resection among people with colorectal cancer treated with cimetidine before, during, or after surgery
- Preliminary evidencesignificant effects in small or poorly designed clinical studies OR conflicting results in adequate studies but a preponderance of evidence of an effect (this is the CancerChoices definition; other researchers and studies may define this differently) of longer survival and a large rise in performance status among people with advanced cancer treated with a daily combination of subcutaneous histamine and oral H2-antihistaminics
- Preliminary evidence of better prognosis and overall survival after primary surgery among people with advanced serous ovarian carcinoma treated with platinum-based systemic chemotherapy and cimetidine
- Insufficient (conflicting) evidencepreclinical evidence only OR clinical studies with such poor or unclear methodology that no conclusion can be drawn OR conflicting findings across clinical studies with no preponderance of evidence in one direction; conflicting evidence occurs when studies find conflicting effects (positive effect vs no effect or negative effect) with the same treatment and the same general study population (same cancer type, for example) (this is the CancerChoices definition; other researchers and studies may define this differently) of an effect on survival among people with stomach (gastric) cancer treated with cimetidine
- No evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. on tumor cell proliferation among people with breast cancer treated with cimetidine before surgery in a small study
Optimizing your body terrain
See More- Modest evidencesignificant effects in at least three small but well-designed randomized controlled trials (RCTs), or one or more well-designed, mid-sized clinical studies of reasonably good quality (RCTs or observational studies), or several small studies aggregated into a meta-analysis (this is the CancerChoices definition; other researchers and studies may define this differently) of higher markers of immune activation among people with cancer treated with cimetidine
- Preliminary evidencesignificant effects in small or poorly designed clinical studies OR conflicting results in adequate studies but a preponderance of evidence of an effect (this is the CancerChoices definition; other researchers and studies may define this differently) of better protection against Haemophilus influenzae type-B after vaccination among people with B cell chronic lymphocytic leukemia treated with ranitidine
Managing side effects and promoting wellness
See More- Preliminary evidencesignificant effects in small or poorly designed clinical studies OR conflicting results in adequate studies but a preponderance of evidence of an effect (this is the CancerChoices definition; other researchers and studies may define this differently) of less liver dysfunction but no evidence of an effect on diarrhea after treatment with gefitinib among people with non-small cell lung cancer treated with histamine type 2 receptor antagonists in a small study
- No evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. on skin toxicity after treatment with gefitinib among people with non-small cell lung cancer treated with histamine type 2 receptor antagonists in a small study
Reducing cancer risk
See More- Modest evidencesignificant effects in at least three small but well-designed randomized controlled trials (RCTs), or one or more well-designed, mid-sized clinical studies of reasonably good quality (RCTs or observational studies), or several small studies aggregated into a meta-analysis (this is the CancerChoices definition; other researchers and studies may define this differently) of moderately lower risk of lung cancer, especially lung adenocarcinoma, among people with type 2 diabetes using histamine-2 receptor blockers; also see evidence from the same study of an increased risk of squamous cell carcinoma and adenocarcinoma among people using H2 blockers in the previous year in Safety and precautions ›
- Insufficient (conflicting) evidencepreclinical evidence only OR clinical studies with such poor or unclear methodology that no conclusion can be drawn OR conflicting findings across clinical studies with no preponderance of evidence in one direction; conflicting evidence occurs when studies find conflicting effects (positive effect vs no effect or negative effect) with the same treatment and the same general study population (same cancer type, for example) (this is the CancerChoices definition; other researchers and studies may define this differently) of an effect on recurrence colorectal cancer treated with cimetidine around the time of surgery
- No evidence of an effectoverall, one or more studies did not demonstrate that a treatment or intervention led to an expected outcome; this does not always mean that there is no effect in clinical practice, but that the studies may have been underpowered (too few participants) or poorly designed. Larger, well-designed studies provide more confidence in making assessments. on adenoma risk or multiple adenoma formation after removal of adenoma(s) among people using either H1 or H2 blockers in a combined analysis of studies
Use by integrative oncology experts
See More- Not mentioned in cancer clinical practice guidelines for cancer care
- Limited use by our program sources
Safety
See More- Increased risk of breast and lung cancers with use
- May raise estrogen levels
- Linked to worse survival among people using H2 blockers treated with PD-1/PD-L1 inhibitors but no effect on gefitinib, Interleukin-2 (IL-2), or ALA-PDT
- Side effects of use are usually mild, but some serious side effects are possible.
- Cimetidine may interact with several medications and therapies.
Affordability and access
See More- Available both by prescription and as an over-the-counter drug
- Moderate cost (between $500 US and $2000 US/year)
Keep reading about H2 blockers
Author
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, program manager, and writer for CancerChoices. 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.
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.
Reviewer
Susan Yaguda, MSN, RN
Susan Yaguda, MSN, RN, has been a nurse for nearly 40 years, working in a variety of healthcare settings. She currently works in Charlotte, North Carolina, at Atrium Health’s Levine Cancer Institute as the manager for Integrative Oncology and Cancer Survivorship. She works with a multidisciplinary team to deliver holistic, evidence-based support and education for patients and care partners at any point along the trajectory of cancer care. She completed the Integrative Oncology Scholars Program through the University of Michigan in 2020, is certified as an Integrative Health Coach through Duke Integrative Medicine and has a post-graduate certificate in Nursing Education from the University of North Carolina, Charlotte. Susan also was awarded the Planetree International Scholar’s Award in 2018 and was recognized by the Daisy Foundation for Nurse Leadership in 2021. Susan has a particular interest in empowering patients and care partners with knowledge to help drive informed decision making and educating nurses on the benefits of integrative care for patients and self-care. She has presented nationally and internationally on integrative oncology and nursing education.
She and her husband, Mark, have two adult children and a very spoiled foxhound. She enjoys hiking, knitting, cooking, and pickleball.
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Last update: December 8, 2023
Last full literature review: May 2023
CancerChoices provides information about integrativein cancer care, a patient-centered approach combining the best of conventional care, self care, and evidence-informed complementary care in an integrated plan cancer care. We review complementaryin cancer care, complementary care involves the use of therapies intended to enhance or add to standard conventional treatments; examples include supplements, mind-body approaches such as yoga or psychosocialtherapy, and acupuncture therapies and self carelifestyle actions and behaviors that may impact cancer outcomes; examples include eating health-promoting foods, limiting alcohol, increasing physical activity, and managing stress practices to help patients and professionals explore and integrate the best combination of conventionalthe cancer care offered by conventionally trained physicians and most hospitals; examples are chemotherapy, surgery, and radiotherapy and complementary therapies and practices for each person.
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