How weed interacts with your medications

 - Revan Health Care

The use of medical marijuana is on the rise. According to PubMedCentral.gov, an estimated three million Americans use medical marijuana to treat various illnesses. The most common uses are for chronic pain, depression, anxiety, and sleep disorders.

Researchers are investigating how the chemicals found in marijuana — cannabidiol (CBD), cannabinol (CBN) and tetrahydrocannabinol (THC) — react with other medications. Some is known, but much research remains to be done, as using marijuana may change how medications work in harmful ways.

There is a significant potential for drug-drug interactions, since both THC and CBD are metabolized by liver enzymes (CYP450) that process many common prescriptions. While research indicates cannabinoids can aid with chronic pain, muscle spasticity, and chemotherapy-induced nausea, evidence shows limited or low-quality benefit for mental health conditions, with risks of adverse events.

Things to remember:

 - Always inform your prescribing physician if you are using marijuana products.

 - The chemicals in marijuana metabolize with the same proteins as most prescription medications.

 - Marijuana can make some medications, like blood thinners, too strong. It can make other medications, like tamoxifen, a breast cancer drug, too weak.

 - Inhaling marijuana smoke introduces chemicals to your bloodstream faster and potentially triggers stronger interactions.

Your body uses proteins to metabolize the chemicals in marijuana the same way it metabolizes the most prescribed medicines. These frequently used drugs include Acetaminophen (Tylenol), anti-anxiety and antidepressant medication, cholesterol medications, Ibuprofen (Motrin), blood thinners and most cancer drugs.

Depending on how much marijuana you use and when you do it, CBD can speed up or slow down the enzymes. As a result, there’s a risk that any medication you take could become too strong or too weak. CBD also affects how quickly your body breaks down other medicines. That means your medication could build up in your body and cause more significant side effects, or even make it less effective.

According to a study in Drug Metabolism and Disposition, your body takes only 30 minutes to break down THC and CBD. However, you must remember that this process produces other chemicals that may remain in your body for up to two weeks. The chemicals will continue to interfere with how your liver and kidneys process and clear medications from your body.

What does that mean? Even a small dose change can make a big difference in how your body responds, because marijuana interacts differently with every drug. The most high-risk interactions happen with medications that have narrow therapeutic windows, or drugs where the margin between an effective dose and a toxic dose is very small.

A good example of these types of medications are:

 - Benzodiazepines or opioids: When combined with marijuana, these pain relievers can increase sedation, particularly in older adults.

 - Clobazam: CBD may increase the sedation effect with this seizure medication and make you sleepy or lethargic.

 - Tamoxifen: Marijuana slows the body’s metabolism of this breast cancer drug, which decreases its strength and impact for people with breast cancer.

 - Warfarin: Marijuana can cause this blood-thinning medication to build up in your body. As a result, you may have an increased risk of internal bleeding and death.

Again, talk with your doctor about how marijuana may affect your prescription medications.

It’s also important to be aware of other adverse effects of the chemicals in marijuana. For example, Cannabinoid Hyperemesis Syndrome (CHS) is a condition caused by long-term, heavy cannabis use, characterized by cyclic episodes of severe nausea, vomiting, and abdominal pain. It typically affects daily users, with symptoms often relieved by hot showers. The only definitive cure is stopping cannabis use, with recovery usually occurring within days to weeks.

Further, anyone on prescription medication can experience unwanted interactions when using marijuana. Those at higher risk are people over the age of 65, people with impaired liver function, those on multiple prescription medications, or people who use marijuana daily or in high doses.

The way you take in marijuana also makes a difference in how the medication will react to the chemicals. The fastest way to get marijuana (chemicals) in your system is by inhaling the smoke, either by directly smoking it or by vaping it. Marijuana in edibles takes longer to absorb. As a result, the concentration in your body is lower and less likely to produce a significant interaction.

Please don’t be discouraged, as it is generally safe to use marijuana with other medications, but you must inform your care team that you use marijuana. They can then observe for any adverse reactions and possibly adjust your doses to ensure safe use.

Although marijuana is a natural substance, it does not mean it is safe to use alongside every medication. You and your doctors can together manage your medications and avoid unwanted interactions.

Revan Health provides welcoming, respectful family medicine for all, from infants to geriatrics. We understand the pain and frustration of not feeling heard by your family care provider. We believe access to respectful care is key to improving medication adherence and overall life satisfaction for patients. Like Revan on Facebook.com/revanhealth or visit us at revanhealth.com.

References:
US Food & Drug Administration
Cleveland Clinic
Franciscan Health

The Gayly online. 4/20/26 @ 12:04 p.m. CST.