Does CBD Mix with Prescription Medications?

Under normal use, cannabidiol (CBD) has few side effects. However, like any drug, it has to be metabolized by your body. This can cause problems with enzyme availability, leading to increased side effects and decreased effectiveness of many prescription medications. Here’s what you need to know to make sure your CBD regimen is compatible with your prescription medications.

How Drugs are Metabolized

Drugs don’t enter and exit your body directly. Instead, they must be metabolized by your digestive system and liver. A family of over 50 enzymes called Cytochrome P-450 (CYP450) break down substances into forms that can be eliminated from your body. The enzymes work in two ways. When the drug first enters your system, the enzymes make a “first pass,” breaking down part of the initial dose. The remaining drug is “bio-available.” Dosages are adjusted to make sure there is enough bioavailable medicine in your system to be therapeutic. From there, the enzymes continue to bind to the drug until it passes out of your body. The correct dosage frequency keeps the drug in your system at therapeutic levels. If you exhaust your supply of an enzyme, it typically takes around 72 hours for your liver to build its supply back up.

Why CBD Products May Interfere with Your Medications

One CYP450 enzyme, CYP3A4, breaks down CBD. If enzymes are binding to CBD, there isn’t as much available to bind to other drugs. CBD also interferes with the effectiveness of this enzyme outside of binding. Early research suggests CBD may also interfere with two other CYP450 enzymes, CYP3A5 and CYP2D6.

The furanocoumarins in grapefruit block CYP3A4. If you take a prescription that warns you not to eat grapefruit, it will probably interact with CBD. There are a wide range of prescriptions with this warning, including antibiotics, antivirals, blood pressure medications, immunosuppressants, cholesterol blockers and pain medications. Similarly, if you have been warned not to consume St. John’s Wort, goldenseal or watercress, it’s probably due to CYP3A4 interactions. While you should be alert for these warnings, this isn’t a foolproof method for determining possible drug interactions. Again, talk to your doctor about possible complications.

What to Look Out for if You Think You’re Having a Reaction

Stop taking CBD and consult your doctor if you have any of these symptoms:

- Increased drug side effects, especially drowsiness and nausea

- Decreased medication effectiveness. This will vary depending on the symptoms the drug is designed to treat. Effects can range from elevated blood pressure or breakthrough seizures.

- Common side effects of CBD, including fatigue, diarrhea, and changes in weight or appetite.