CBD and Medications: What Should You Know?

How Can CBD Affect the Way Medications Work?

Your body uses enzymes to break down medication. One important group is the cytochrome P450 (CYP450) enzyme system. These enzymes are found mainly in the liver and help your body process many different medicines.

CBD can inhibit certain enzymes, including CYP2C19. This means some medications may be broken down more slowly, causing higher levels of the drug to remain in your bloodstream. As a result, the risk of side effects may increase.

However, the opposite can also happen. Some medications need to be converted by enzymes before they become active. If CBD interferes with this process, the medication may become less effective. The impact depends on the specific medicine and the dosage.

CBD and the Grapefruit Warning

Does your medication come with a warning about grapefruit or grapefruit juice? If so, you should also be cautious with CBD. CBD can affect some of the enzymes involved in breaking down medications. Although it doesn't work in exactly the same way as grapefruit, a grapefruit warning is a good reason to take extra care.

If your medication carries a grapefruit warning, don't use CBD without first consulting your doctor or pharmacist.

Which Medications Can Interact With CBD?

Researchers have investigated potential interactions between CBD and various medications. Below are some important examples. While certain interactions have been clearly demonstrated, others are considered possible based on how the medicines work in the body.

Blood Thinners

There have been reported cases of CBD affecting blood clotting in people taking warfarin. In these cases, the INR level increased. INR is a measurement used to monitor how quickly blood clots. A higher INR means blood may take longer to clot, increasing the risk of bleeding.

Other blood thinners, such as acenocoumarol and phenprocoumon, work in a similar way to warfarin. However, their interactions with CBD have not been studied to the same extent. If you take either of these medications, discuss CBD with the healthcare professional responsible for monitoring your blood clotting.

Clopidogrel presents a different potential risk. This medication helps prevent blood clots but must first be activated by the body. CBD can inhibit an enzyme involved in this activation process, potentially making clopidogrel less effective.

Antidepressants

CBD may slow down the breakdown of certain antidepressants. This has been studied with medications such as citalopram.

In a small study, researchers found higher levels of citalopram in the blood when it was taken alongside CBD. This could potentially increase the risk of side effects, although it remains unclear whether these higher levels actually lead to more problems. The findings do show that CBD can affect how the body processes this medication.

Sleeping Pills and Sedatives

Combining CBD with sleeping pills or sedatives can increase drowsiness. This includes benzodiazepines such as oxazepam and diazepam.

The interaction isn't just about how medications are broken down. CBD and sedatives may also enhance each other's calming and sedating effects. This can leave you feeling sleepier, dizzier and less alert, with slower reaction times.

Extra caution is also needed when combining CBD with strong painkillers, such as oxycodone and other opioids. Driving or operating machinery can become particularly dangerous.

Epilepsy Medications

Some epilepsy medications have well-documented interactions with CBD. For example, CBD can cause an active breakdown product of clobazam to remain in the body for longer. This may increase drowsiness and other side effects.

Combining CBD with valproate (valproic acid) can increase the risk of elevated liver enzyme levels. This may indicate liver problems. For this reason, a doctor may recommend regular blood tests to monitor liver function.

There is also a prescription medication containing CBD as its active ingredient: Epidyolex. It is used to treat certain forms of epilepsy, including Dravet syndrome, Lennox-Gastaut syndrome and seizures associated with tuberous sclerosis complex. For Dravet syndrome and Lennox-Gastaut syndrome, Epidyolex is used as an additional treatment alongside clobazam. For tuberous sclerosis complex, it is used together with other epilepsy medications. Treatment is supervised by a specialist.

Epidyolex is an approved prescription medicine and is not the same as over-the-counter CBD oil.

Immunosuppressants

Research has shown that CBD can significantly increase blood levels of tacrolimus. This medication is commonly used after organ transplants to prevent the body from rejecting the transplanted organ. Excessively high tacrolimus levels can cause serious side effects. That's why doctors regularly monitor its concentration through blood tests. If you take tacrolimus, always consult your treating doctor before using CBD.

Does the Amount of CBD Matter?

The amount of CBD you take can influence potential interactions with medication. Much of the available research has focused on high, medically prescribed doses of CBD. Less is known about the risks associated with lower doses.

However, taking a low dose doesn't automatically mean CBD is safe to combine with medication. Taking CBD and your medication at different times of the day doesn't necessarily prevent interactions either. CBD can affect how your body processes medicines for longer than just the period immediately after taking it.