CBD Drug Interactions: What You Need To Know

When taken on its own, CBD is a powerhouse wonder-drug. But when other drugs and medications come into the picture, you always need to consider the implications. Even herbal medicines or certain fruits are eaten together are considered an undesirable interaction of chemicals.

Most of the time, these interactions are very mild, and a person might not even notice them. Sometimes, however, certain drugs taken together cause contraindications that can be severe.

For the most part, CBD is safe to take, with very few side effects and very mild interactions with other drugs. With that being said, after taking CBD, there is a change that happens in the way that we metabolize a number of different chemicals. This change lasts for a short time after use. So it’s good to know what those changes are and how to best manage taking CBD with other drugs.

Understanding CBD interactions

The most important things to understand when consuming CBD with other drugs relate to the way that we metabolize. CBD affects a number of different functions of the body through the endocannabinoid system. With most other drugs, this does not pose any threat or danger.

However, almost every drug or substance you consume will go through an enzymatic breakdown in your liver. This includes CBD.

To understand CBD interactions, you need to understand that everybody metabolizes at a different rate. This is due to a number of things, including the health of your liver and the kinds of substances that you are taking.

As every drug will go through this process of metabolism, it is important to make sure that the health of the liver and gut are not being compromised by the mixing of certain chemicals.

The Dangers of Mixing Drugs

There are dangers associated with mixing drugs. This is largely due to the fact that certain drugs have certain effects which are not compatible with other drugs. Danger also comes as a result of the byproducts in the metabolism process chemically reacting with one another.

Although we don’t know much about how cannabis affects blood sugar at this stage, there is some speculation that taken together with other drugs, blood glucose levels could drop too much. There is also a possible danger in mixing CBD with drugs used for blood thinning, as it may increase or amplify their effects.

As you can see, certain chemicals will amplify the effects of another chemical in the same environment. In a lot of cases, this can be seen as a potential danger. However, it does not necessarily mean that one needs to stop using a certain drug, but being aware of the dangers may alter the dosage that is required for treatment.

CBD Oil Drug Interactions: The CYP450 Pathway

As we mentioned briefly, it is the metabolism of drugs that are the biggest gameplayer in assessing drug interactions. Certain drugs amplify the effects of other ones, while others inhibit the metabolism of other drugs completely. The medical profession realizes this through the CYP450 pathway, which is a metabolic enzyme system in the liver which breaks down intoxicants and drugs.

The way that different drugs move through this metabolic pathway in each individual usually dictates the dosage required and the contraindications of certain pharmaceutical drugs.

What is the Cytochrome P-450 System?

This system is a metabolic pathway consisting of a number of different enzymes. It takes place in the liver. Over 60% of pharmaceutical and recreational narcotics will go through this metabolic pathway in order to take effect or to be discarded and excreted by the body.

This system is at the mercy of the drug that is being consumed. It means that sometimes, certain drugs actually inhibit this process, while others can speed it up. When a drug is taken on its own, this is not usually a problem and can be managed with dosage. However, when drugs are taken in tandem, it can yield some very interesting and unwanted results.

An unhealthy liver can also pose some problems when it comes to the functioning of this system. Drugs might not necessarily be metabolized as predicted if the liver is unwell, and this can also cause some undesirable drug interactions.

Why Does CYP450 Matter?

Ultimately, CYP450 matters because it is the metabolic pathway through which most drugs will travel! Any kind of alteration to this process is going to alter the way a certain drug is metabolized, whether that is a positive or negative result.

If a certain drug alters the way that we metabolize other drugs, the effects can be fatal. Sometimes, avoiding fatalities is a simple as changing the dose to be in line with the changes that have happened to this system. This is why medical professionals always ask what other medication a person is taking before prescribing and dosing a new kind of medicine.

With that being said, medical professionals are just humans. They are not encyclopedias. It is impossible to know the exact chemical interaction between all drugs on the planet. However, with what we do know, we are able to predict how certain drugs will affect the CYP450 system, and therefore make decisions about which drugs go well together and which ones do not.

Effects of CBD on the Cytochrome P-450 System

Have you ever wondered why certain, seemingly benign things, such as grapefruit are considered to be contraindications to a lot of drugs? Well, it’s because of the fact that they inhibit a lot of what goes on in the Cytochrome P-450 system. The same is true of CBD.

What does it mean exactly to inhibit the Cytochrome P-450 system? Well, CBD acts as something called a competitive inhibitor. It means that for the time that it is in the system, it binds to the binding site on the enzyme, temporarily inhibiting it. During that time, other drugs cannot be processed the way that they usually would.

This can lead to drugs staying longer in the system than they otherwise would or should, due to the fact that they cannot be broken down by liver enzymes. Mild effects can simply be that the usual dose of a drug is stronger. More severe effects can be an overdose.

You might find it interesting that grapefruit, watercress, and St John’s Wort also have this effect on the CYP450 system. So it’s not just about drugs. Even certain foods can cause interactions that cause unwanted side effects.

Known Drugs That Interact With Cannabidiol

As it stands, we know that certain drugs interact with CBD in a number of ways. Remember, if you are using any of these drugs, it does not necessarily mean that you should not use CBD. It might mean consulting a healthcare professional about how and when to dose to avoid dangerous interactions.


Steroid medications are usually used to treat inflammatory conditions such as rheumatoid arthritis or certain gut conditions.

HMG CoA Reductase Inhibitors

These drugs are sometimes called statins and are used to reduce cholesterol. Many drugs are much stronger than statins in the CYP450 system, and therefore the effect of statins can be reduced.

Calcium channel blockers

Calcium channel blockers are medications usually prescribed to cardiovascular patients. They relax the blood vessels and reduce some of the work the heart has to do to pump blood. These drugs can potently inhibit or induce the behavior of CYP450.


Antihistamines are prescribed to those who have allergies. In general, these drugs do not bind strongly to the CYP450 system. Therefore, when drug interactions are taking place, there is a big threat of overdose.


Benzodiazepines are mild tranquilizers that are prescribed to patients who have anxiety disorders. Potential interactions include the build-up of benzodiazepines in the system due to inhibition of the CYP450 by other drugs.


Antiarrhythmics are drugs prescribed to treat those who have an abnormal heart rhythm. This drug is a potent inhibitor of the enzymes in the CYP450 system, therefore causing other drugs to be metabolized much slower.


Most of us are familiar with antibiotics. They are used to treat infections. Antibiotics are known to inhibit the metabolism of other CYP450 drugs by binding very strongly to the enzyme-substrate sites. This can lead to an overdose of the interacting drug.


Anesthetics are usually administered before a surgery to tranquilize a patient. They are also strong inducers or inhibitors of the CYP450 system, depending on which anesthetic is administered. This is why the nurse always asks if you have taken any other drugs leading up to the administration of anesthetics.


CBD Drug Interactions

These drugs are used to manage psychosis, and they do so by altering the brain chemistry to reduce hallucinations and other symptoms of psychosis. The power of antipsychotics to inhibit the CYP450 system is incredibly strong. Therefore, it is easy to overdose on other drugs if they are being used in tandem with antipsychotics.


Antidepressants are drugs that are prescribed to patients with strong symptoms of depression. As with antipsychotics, they strongly inhibit the CYP450 system enzymes and should not really be used in conjunction with other drugs that use this same metabolic pathway or dosage should be very closely monitored.


Interestingly, the desired effects of anticonvulsant or anti-epileptics is a result of a breakdown product of these drugs. They do not bind strongly to the CYP450 system, so the fact that it is not being broken down means it is not effective in the presence of interactions.


Beta blockers are prescribed to lower blood pressure. They do this by inhibiting the effect of hormone epinephrine. It does not bind strongly to the enzyme sites in CYP450, and therefore the effects can be decreased in the presence of other CYP450 dependent drugs.


Sulfonylureas are antidiabetic drugs that are usually prescribed to treat diabetes mellitus type 2. They do this by increasing the amount of insulin that is released by beta cells in the liver. In general, the main interactions are other drugs that induce the effects of the CYP450 system.

How to Use CBD Safely

The best thing you can do if you are afraid of an unsafe drug interaction is to ask your doctor. He or she might not tell you to stop using CBD entirely but might give you some advice about how much to take and when to take it to avoid any unwanted contraindications. The safest way to take CBD is with a doctor’s advice.

If you are not taking any other drugs, then you can feel free to use CBD. It is not dangerous in and of itself. Rather, it can pose potential threats if you are taking other drugs that interact with the same metabolic pathway. If you are on any pharmaceutical medication, you are always best off consulting a healthcare professional about the possible risks of using CBD.

Farma Health Desk Editor

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