Does Marijuana Help With Breast Cancer?

Medically Reviewed by Neha Pathak, MD on January 03, 2021

April Curtis has been living with stage IV breast cancer for 6 years. The cancer itself, as well as some of the treatments for it, have caused a variety of debilitating side effects, especially nausea and severe pain. For a while, her doctors tried to ease these issues with higher and higher doses of medication, including strong opiates, but she was still miserable. About 3 years ago, she decided to give marijuana a try.

“For nausea, it’s wonderful,” says Curtis, 39. “For pain, I can’t rely on it 100%, but it allows me to use a lower dose of opiates.”

Curtis lives in Pennsylvania, one of 36 states where medical marijuana is legal.

In Colorado, one of the first states to legalize cannabis, “it would be hard to find a sizable group of [cancer] patients who aren’t using it,” says Virginia Borges, MD, director of the Breast Cancer Research Program at the University of Colorado Cancer Center.

A survey found that 42% of people who responded had tried medical cannabis products to deal with breast cancer symptoms or treatment side effects. But does it actually work?

Symptom Relief

Although there’s not a lot of proof that cannabis can directly fight cancer, there’s growing agreement among patients and oncologists that it offers powerful symptom relief for many people.

“I think you still need to use conventional therapies to treat the disease, but if you have symptoms that might benefit from cannabis, you should consider using it,” says Donald Abrams, MD, an integrative oncologist and professor emeritus at the University of California San Francisco Osher Center for Integrative Medicine. (Of course, make sure it’s legal in your state. Click here to check.)

“As an oncologist for 38 years, I can tell you it’s an effective antiemetic,” Abrams says. In addition to fighting chemo-induced nausea and stimulating your appetite, it may help relieve certain types of pain, he says.

Cannabis also has the potential to ease anxiety and insomnia, as well as the joint stiffness and hot flashes that hormonal treatments often cause, Borges says. “I don’t think it’s a placebo effect, because I’ve seen it too many times,” she says. “I have patients who stopped it, and their symptoms came back.”

In the survey, 75% of people with breast cancer who had tried cannabis said it was helpful. “Most of the survey responders wanted a solution to a side effect; they were not looking to get high,” says founder Marisa Weiss, MD, director of Breast Radiation Oncology at Lankenau Medical Center in Pennsylvania.

So why is there so little hard proof of cannabis’ benefits? It has more to do with the law than anything else. Although some research has been done on the effects of cannabis in people with cancer, it was mostly in the 1980s and 1990s and limited to synthetic versions of the drug.

"Cannabis remains a Schedule I substance [under federal law], meaning it has no official accepted medical use and a high potential for abuse. That makes doing research a challenge,” Abrams says.

Another issue is that the only way to get cannabis for research is through the National Institute for Drug Abuse (NIDA), and the strains it carries aren’t the same as what’s often sold at dispensaries. “NIDA also tends to mostly fund studies on the potential harmful effects [of cannabis], but they are starting to fund more studies looking at potential therapeutic benefits,” Abrams says.

Although the synthetic cannabis drugs dronabinol (Marinol, Syndros) and nabilone (Cesamet) are available by prescription, Borges says that people tend not to respond to them as well as they do to real cannabis. “The most logical explanation is that Marinol doesn’t capture all of what’s active in the plant,” she says.

Trying to turn cannabis into mass-produced prescription products might be misguided, Abrams says. “This is a botanical remedy that’s been around thousands of years. I don’t believe it needs a package insert.”

Possible Side Effects

Abrams says that, if you buy from a reputable dispensary and check with your oncologist to make sure it doesn’t interact with any of your medications, cannabis is very safe to try. “I think it’s safer than alcohol,” he says. “I’ve never had to hospitalize a patient with complications from cannabis use.”

However, some people do have side effects. They may depend on your body chemistry as well as the specific product you use, the dose, and how much it has of the psychoactive compound tetrahydrocannabinol (THC).

Cannabidiol (CBD) is the other well-known compound in cannabis. It alone will not make you “high.” It rarely causes side effects, but dry mouth, fatigue, and diarrhea are possible.

THC may cause mood and memory changes and altered senses, especially when taken in high doses and not balanced out with enough CBD. Dizziness, breathing problems, and hallucinations or paranoia are also possible.

Weiss cautions that anyone who has significant heart disease or has had a heart attack in the past 6 months should avoid cannabis, as should anyone taking blood thinners. Cannabis can also raise or lower blood pressure, Abrams says. He adds that people who are using immunotherapy for breast cancer should be cautious, as there is some evidence that cannabis might interfere with this type of treatment.

Lastly, “if you’ve experienced side effects from using cannabis in the past, it’s best to avoid it and look for alternative options to alleviate symptoms,” Weiss says.

If You Decide to Try It

The first step is to talk to your oncologist to make sure that cannabis won’t interact with your treatments. If your doctor doesn’t know enough about the topic, “I recommend talking to a pharmacist trained in cannabis,” Weiss says. “Pain management doctors, like palliative care physicians, can be knowledgeable and helpful too.”

It’s also best to seek out a medical dispensary rather than a recreational one, as the employees there are more likely to have experience helping people with cancer. Because cannabis products aren’t regulated the way FDA-approved drugs are, a local dispensary worker may need to advise you. Some are very well-informed, but it can be hit or miss.

“I felt like I knew more about it than the 20-somethings at the dispensary,” says Judith Basya, who was 44 when she tried cannabis in 2015 for nausea and insomnia related to chemotherapy for stage II breast cancer.

“I bought a few things to try, and when I went back the second time, I knew exactly what I wanted,” she says. “Don’t be afraid to ask questions, but be open to experimenting a bit until you figure out what works for you.”

Other tips:

  • If your main complaints are insomnia, hot flashes, or joint stiffness, try CBD alone first. In many states, CBD products are sold at drugstores and even grocery stores.
  • People seeking relief from nausea, vomiting, and a loss of appetite usually do better with the full plant, which includes THC.
  • The only CBD-to-THC ratio that has been studied is 1:1, Abrams says, but that doesn’t mean it’s the right fit for you. “At a dispensary, they might recommend 8:1 or 16:1 on the basis of first-hand info from other patients,” he says. It’s OK to try different ones as long as you start with a low dose and go slow.
  • Steer clear of edibles. People often end up overdoing it because they eat a little and don’t feel anything, Abrams says. Cannabis that’s ingested takes 2.5 hours to go through your digestive system and reach peak concentration in your bloodstream. Vaping the whole plant (rather than oils or extracts) tends to be a better bet, as the drug will peak in 2.5 minutes and dissipate within 30 minutes. “If you want better control over the onset, depth, and duration, then inhalation is better than ingestion,” he says.
  • If you’re wary of vaping (which is different from smoking), consider a tincture or oil that you put under your tongue. Some of it gets absorbed right away. You swallow the rest so it’s released more slowly. “It’s a good hybrid option for some people, because you get some effect right away, but you don’t have to dose as often,” Abrams says.

Show Sources


April Curtis, breast cancer patient. “Medical Cannabis.”

Donald Abrams, MD, integrative oncologist and professor emeritus at the University of California San Francisco Osher Center for Integrative Medicine.

National Conference of State Legislatures: “Deep Dive: Marijuana,” “State Medical Marijuana Laws.”

Marisa Weiss, MD, director of Breast Radiation Oncology at Lankenau Medical Center in Pennsylvania and founder and chief medical director of

Mayo Clinic: “What are the benefits of CBD — and is it safe to use?”

NIH National Center for Complementary and Integrative Health: “Cannabis (Marijuana) and Cannabinoids: What You Need to Know.”

NIH National Institute on Drug Abuse: “Marijuana DrugFacts.”

Virginia Borges, MD, director of the Breast Cancer Research Program at the University of Colorado Cancer Center.


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