Hold off if you have known liver damage, says Dr. Patel. In a study done on mice published earlier this year, the dose of CBD used to protect against seizures was found to induce liver damage. According to other animal research, CBD may increase levels of liver enzymes, raising concerns about liver toxicity in patients taking methotrexate.
People who take Epidiolex for epilepsy are more likely to develop abnormal liver enzymes, as well as sleepiness and other symptoms, if they are also using valproic acid to control seizures.
“Based on what we know now about the way CBD is metabolized, I would not expect significant drug-drug interactions with drugs commonly used in arthritis treatment, such as methotrexate, and most nonsteroidal anti-inflammatory drugs (NSAIDs). I would advise caution on one NSAID, diclofenac, because there isn’t information on how CBD affects — if at all — the enzyme that metabolizes it,” says Dr. Bemben.
Are there some people who should stay away from CBD?
CBD inhibits some enzymes in this family. This makes them break down certain drugs more slowly, which could potentially increase side effects unless your doctor adjusts the dose. On the other hand, CBD induces other enzymes in this family, which speeds the breakdown of certain drugs so they may potentially be less effective unless the dose is increased.
Yes, for several reasons. “As we age, our livers and kidneys may be slower to eliminate drugs from the body. In addition, older patients and those with chronic health problems are more likely to be using multiple medications, so the risk for drug interactions increases,” says Dr. Bemben.
If I stick with a CBD cream, does that reduce the risk of drug interactions?
“We use other therapies that cause liver injury, like nonsteroidal anti-inflammatories (NSAIDs). If liver enzymes go up in someone on methotrexate, we would generally hold the drug other than methotrexate [for example, CBD or an NSAID] to see if the enzyme levels normalize,” says Michael Weinblatt, MD, professor of medicine at Harvard Medical School in Boston.
“If you fill all of your medications at the same pharmacy, your pharmacist will be able to assess for drug interactions for all of them, regardless of who prescribed them. You should still let the pharmacist know about over-the-counter medications, herbs, and supplements — including CBD — that you don’t get through the pharmacy. It is important to bring the CBD product to your doctor and pharmacist so they can check the amount of CBD and other ingredients it contains,” says Dr. Bemben.
Products containing cannabidiol (CBD) seem to be all the rage these days, promising relief from a wide range of maladies, from insomnia and hot flashes to chronic pain and seizures. Some of these claims have merit to them, while some of them are just hype. But it won’t hurt to try, right? Well, not so fast. CBD is a biologically active compound, and as such, it may also have unintended consequences. These include known side effects of CBD, but also unintended interactions with supplements, herbal products, and over-the-counter (OTC) and prescription medications.
Doubling up on side effects
Researchers from Penn State College of Medicine evaluated existing information on five prescription CBD and delta-9-tetrahydrocannabinol (THC) cannabinoid medications: antinausea medications used during cancer treatment (Marinol, Syndros, Cesamet); a medication used primarily for muscle spasms in multiple sclerosis (Sativex, which is not currently available in the US, but available in other countries); and an antiseizure medication (Epidiolex). Overall, the researchers identified 139 medications that may be affected by cannabinoids. This list was further narrowed to 57 medications, for which altered concentration can be dangerous. The list contains a variety of drugs from heart medications to antibiotics, although not all the drugs on the list may be affected by CBD-only products (some are only affected by THC). Potentially serious drug interactions with CBD included
CBD can alter the effects of other drugs
Many drugs are broken down by enzymes in the liver, and CBD may compete for or interfere with these enzymes, leading to too much or not enough of the drug in the body, called altered concentration. The altered concentration, in turn, may lead to the medication not working, or an increased risk of side effects. Such drug interactions are usually hard to predict but can cause unpleasant and sometimes serious problems.