Should you tell your doctor if you're using marijuana?

Making your doctor aware that you’re using medical marijuana is not only a courtesy, but a potentially life-saving act. Marijuana interferes with the metabolism of many drugs, including some chemotherapies, and can affect how effective these drugs are.

What are the benefits of telling your doctor if you’re taking medical marijuana?

1. Your doctor can more accurately make a plan of treatment that is specific to you

2. Your doctor can assess whether medical marijuana is safe to take with other prescriptions you may be taking

It’s a two way street - tell your doctor for full transparency

Although the medical use of cannabis (the plant) is legal in several states and the District of Columbia, it is still against federal law for doctors to prescribe it. That means, legally speaking, your doctor cannot write you a prescription for cannabis. Instead, your doctor can write an endorsement, attestation or certification of the possible efficacy of medical marijuana in treating your particular condition (Cannabis and Cannabinoid Research, Volume 1.1 2016 pg. 42).

However, not all physicians will be comfortable with signing a certificate. In many states, there are certain physicians available to review your individual case for a medical marijuana card. To apply for a card, the attestation of a doctor is required. Each state will charge a different fee for the card. Information on legal limits and state requirements can be found here. (Be sure to scroll down the page for full information.)

We also need to discuss some doctors’ “don’t ask, don’t tell” attitude toward medical marijuana. With medical options approved by the Food and Drug Administration (FDA) being available, and nearly half of all states legalizing medical marijuana, this doesn’t help patients navigate their integrated or complementary medicine options with confidence. It is best to have a provider who is comfortable and informed, because there may be an interaction with other treatment options you are pursuing.

The impact of medical marijuana on your treatment

Regardless of whether or not marijuana is legal in your state, it is important to tell your doctor if and how you use marijuana, either recreationally or medically, and the frequency of your use. As we mentioned before, marijuana interferes with the metabolism of many drugs, including chemotherapeutic agents and herbal supplements. Marijuana is metabolized in the liver as are many chemotherapy agents.

Should you take medical marijuana instead of or along with conventional therapy?

If you are using cannabis in place of conventional therapy, you should definitely notify your doctor. As of now, there is no evidence to suggest it should be used as a treatment in and of itself. There is only a small window when treatment is most effective, so the time spent attempting to use cannabis as a “cure” may result in the cancer progressing to a stage where it is more difficult to treat.

It is important to note that many people who currently claim they’ve been cured by cannabis or hashish oil have been on standard therapy at the same time (Lancet Oncology, Volume 16, October 2015). Dr. Donald Abrams at the University of California San Francisco said, “What really upsets me the most, though, is when I see a patient with a potentially curable malignancy who is using cannabis oil instead of conventional therapy. In some situations, the window of opportunity for a potential cure may close when their cancer progresses on cannabis alone.”

So, let your doctor know if you’re taking medical marijuana so that he or she can best take care of you.

If you or someone you love is considering medical marijuana, do your research, look at the references we provide, talk with others, and speak with your doctor. To get an in-depth understanding or answers to other questions about medical marijuana, watch the What You Need to Know About Medical Marijuana & CRC webinar.

The Colorectal Cancer Alliance does not endorse or recommend any specific treatment or screening method for colorectal cancer; rather we serve as a source of scientifically accurate medical information to help empower patients and their caregivers to make informed decisions in consultation with their health professionals.

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