Is Long-term Use of Benzodiazepines a Risk for Cancer?


A large study of the population in Taiwan reveals that long-term use of benzodiazepine drugs, commonly prescribed for anxiety, significantly increases the risk for brain, colorectal, and lung cancers. The research, published open-access in the journal Medicine, also identifies the types of benzodiazepines that carry the greatest cancer risk.

Benzodiazepines are a group of central nervous system depressants that are commonly prescribed in the general population. Public health research reveals that approximately six to ten percent of US adults were prescribed a benzodiazepine in 2010 and that, in some countries, as many as forty-two percent of the elderly use these drugs.

Clonazepam, brand name Klonopin, was found to carry the greatest cancer risk.
Clonazepam, brand name Klonopin, was found to carry the greatest cancer risk.

There has been debate in the research over the risk for cancer posed by the long term use of benzodiazepines. Animal studies have reported a relationship between the use of these drugs and thyroid cancer, breast cancer, and liver cancer. While the relationship is not yet definitive, some researchers point out that the risk may be unnecessary as “there is no persuasive evidence for benefits from long term use.”

In this study, researchers use the Taiwanese National Health Insurance system to gather information about benzodiazepine use and cancer risk. They found that certain benzodiazepines carried a greater risk than others.

Namely, clonazepam (Klonopin), lorazepam (Ativan), alparazolam (Xanax), bromazepam (Lexotan), zolpidem (Ambien), and zopiclone (Lunesta) were found to have a high risk for cancer while chlordiazepoxide (Librium), diazepam (Valium), medazepam (Azepamid), oxazepam (Serax), and nitrazepam (Mogadon) did not have a significant association with cancer.

Clonazepam (Klonopin) was found to be the most dangerous, carrying a fifteen percent higher risk for cancer than all other benzodiazepine drugs.

The research also revealed that benzodiazepines exposure increased the overall cancer risk up to 21%, specifically for brain 98%, colorectal 25%, lung 10%, esophagus 59%, prostate 36%, bladder 39%, liver 18%, pancreas 41% and other cancers 27%.

This article is published open-access and can be read in full here



Iqbal, Usman, Phung-Anh Nguyen, Shabbir Syed-Abdul, Hsuan-Chia Yang, Chih-Wei Huang, Wen-Shan Jian, Min-Huei Hsu, Yun Yen, and Yu-Chuan Jack Li. “Is long-term use of benzodiazepine a risk for cancer?.” Medicine94, no. 6 (2015).

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Justin Karter
MIA Research News Editor: Justin M. Karter is the lead research news editor for Mad in America. He completed his doctorate in Counseling Psychology at the University of Massachusetts Boston. He also holds graduate degrees in both Journalism and Community Psychology from Point Park University. He brings a particular interest in examining and decoding cultural narratives of mental health and reimagining the institutions built on these assumptions.


  1. Many papers have been show to show a correlation between stress and the prevalence of cancer.
    While not as many, a few have posited a theoretical mechanism. Stress has been shown to likely reduce efficacy of killer t cells.

    That said-there is no evidence, nor credible mechanism to show how benzodiazepines cause cancer: it is called…a correlation..

    If anything, there would be an easier way to show that benzodiazepines reduce cancer rates-if one wanted to look at the science.

    Yet another MIA baseless attack on psychopharmacology. There are easier ways to do it than this article.


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    • Yes, I think the logic of the article is a bit lacking – one would have to have two groups of people diagnosed with anxiety problems, and give one benzos and the other not, and then measure cancer outcomes, to have any good data.

      But I think the MIA editor wasn’t distorting the article at all in reporting it – it’s just that the article itself was not very broad minded.

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    • Psychopharmacology is it’s own critique, way up there, over and beyond, pharmacology itself. Psychopharmacology, after all, is not the only place within the field of medicine and pharmacology where you find iatrogenic injury and death.

      We live in a prescription drug culture. What better evidence do you need to support the claim that this prescription drug culture exists than the term “psychopharmacology”?

      “Feeling bad”, in itself, is not “disease” nor is “feeling better”, when it comes down to it, a “symptom” of “health”.

      Drugs have toxic effects. That people on benzos long term are more susceptible to dementia than other people should come as no surprise to anybody. That any number of toxic elements have something to do with the incidence of cancer should come as no surprise to folks either.

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    • I don’t believe we are bashing psychopharmacology here. If anything, we are striving to learn the truth on the dangers of psychiatric drugs. Critical Withheld information that our doctors refuse to provide us with. Gp’s, pediatricians, and Psychiatrists prescribe these drugs to multi- millions of us, many greatly harmed. Myself included. I only want the truth.

      Carcinogenicity of psychotropic drugs: A systematic review of US Food and Drug Administration – required preclinical in vivo studies –

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    • Cancer is primarily a disease of toxicity; stress however doesn’t help. It’s also true that correlation doesn’t equal causation. Still it does no harm to point it out. I think the “psychopharmacology” lobby can handle it.

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  2. The ones that were not linked to cancer came out in the first 5 years of the benzos, between 1960 and 1965: Librium was the first, then Valium, Mogadon and Serax.Medazepam (Azepamid) is older but is not approved in the US.

    Klonopin, Ativan, and Xanax were approved 1975-1981

    Lunesta, Ambien, and Lexotan, 2004-2007.

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