Yes, CBD can interact with many medications by altering their concentration in the blood, sometimes significantly. TheANSM (French National Agency for Medicines and Health Products Safety) reports documented cases between 2017 and 2023. Before taking any medication, speak to your doctor or pharmacist: this remains the only reliable way to assess your individual situation.
In short:
- At high doses, CBD inhibits the CYP3A4 and CYP2C19 enzymes, while the dose, route of administration and liver condition modulate the effect.
- Clobazam, tacrolimus and warfarin are among the most affected treatments, with neurological monitoring, blood tests or INR control as appropriate.
- Between 2017 and 2023, French poison control centers recorded 58 interactions, while four serious cases were reported in 2021 and 2022.
- Unusual bleeding, an epileptic seizure, profound drowsiness, or a yellowish complexion with abdominal pain warrant urgent medical attention.
- Before taking any medication, inform a doctor or pharmacist about your treatments and never change them without medical advice; blood monitoring may be necessary.
Table of Contents
- How CBD alters drug metabolism
- Drugs and risk classes identified
- Signs to watch for in case of interaction
- What to do if you are already taking medication
- Learn more about the specific interactions
- CBD is not a neutral product
- Traceable CBD products, to be used with medical advice
- Frequently Asked Questions
- Sources
How CBD alters drug metabolism
The liver breaks down most medications using enzymes called cytochrome P450, including CYP3A4, CYP2C19, and CYP2C9. CBD acts directly on these enzymes, and the drug manual describes it as a potent inhibitor of CYP2B6, CYP2C19, and CYP3A4. Other enzymes, UGTs, play a similar role in some treatments.
Two opposing mechanisms can occur. When CBD inhibits an enzyme, the drug accumulates in the blood, increasing the risk of toxicity. When it induces the enzyme, the effect is reversed: the drug is eliminated more quickly, and its effectiveness decreases.
Several factors cause the intensity of this phenomenon to vary from person to person:
- The dose of CBD consumed, since a marked inhibitory effect appears mainly at high doses.
- The route of administration, oil, gummies and vapor do not have the same absorption rate.
- The state of the liver, reduced liver function amplifying the risk of accumulation.
- Individual genetic variations, which modify the natural activity of these enzymes depending on the person.
Drugs and risk classes identified
Certain treatment regimens appear repeatedly in the reported cases. Here are the most documented, in order of available evidence:
- Anticonvulsants : clobazam, valproic acid and carbamazepine are among the best-established interactions, with cases where stopping CBD has normalized plasma concentrations, according to the pharmacology report.
- Immunosuppressants : tacrolimus and sirolimus require close plasma monitoring, as a systematic review published in Frontiers identified cases of significant increases in their concentration.
- Anticoagulants : Warfarin exposes patients to a risk of INR modification, which can unbalance the anticoagulant effect in one direction or the other.
- Antidepressants : A controlled clinical trial measured an increase in citalopram exposure of approximately 43% when co-administered with CBD, according to a study published on PMC.
- Opioids and methadone : cases of overdose have been reported, while statins, proton pump inhibitors and certain antifungals also appear on the watch lists.
The ANSM itself publishes a non-exhaustive list of potentially affected drugs, including tramadol, morphine, warfarin, tacrolimus and citalopram, which can be consulted on its website.
Signs to watch for in case of interaction
Reported effects range from mild symptoms to complications requiring prompt medical attention. The most frequent signs remain moderate:
- Unusual drowsiness or marked fatigue.
- Dizziness and nausea.
- Diarrhea.
- Persistent headaches.
Between 2017 and 2023, poison control centers in France recorded 58 cases of interactions between CBD and medications, a figure that reflects a measurable clinical reality rather than a theoretical risk. During the 2021-2022 period, regional pharmacovigilance centers reported 4 cases deemed serious to the ANSM (French National Agency for Medicines and Health Products Safety).
More serious signs include elevated liver transaminases, seizures in patients taking antiepileptic drugs, a tacrolimus overdose confirmed by blood tests, or unusual bleeding in people taking warfarin. These situations require immediate medical attention, not just home observation.
What to do if you are already taking medication
The basic rule remains simple: inform before acting. Here is the order of steps to follow.
- Speak to your doctor or pharmacist before taking any CBD, even in the form of an ingested food supplement or cosmetic.
- Never change or stop a prescribed treatment on your own initiative, even if you experience an unusual effect.
- Ask if a liver function test, INR check, or blood test for your medications is necessary before and after introducing CBD.
- Adapt monitoring to your treatment: a patient on warfarin will monitor their INR, a patient on tacrolimus their plasma level, a patient on clobazam their neurological balance.
Pro tip: Keep a written list of all your treatments, including supplements, to show to each healthcare professional you consult.
Certain signs justify an immediate visit to the emergency room: profound drowsiness that is difficult to wake up from, unusual bleeding, seizure, or abdominal pain associated with a yellowish tint suggesting liver damage.
Learn more about the specific interactions
Some interactions warrant specific attention depending on the treatment involved. We have detailed the case of interactions with antiviral medications for readers undergoing this type of treatment, as well as a specific point on CBD and lansoprazole, a frequently prescribed proton pump inhibitor.
The form of the product also influences the extent of the effect: our explanations of CBD bioavailability help explain why an oil and a smoked flower do not act with the same intensity on the body. Since the liver remains the central organ for this metabolism, our article on the effects of CBD on the liver is a useful complement to this reading.
Each product we offer is selected based on traceability and legal compliance, a commitment applied to our entire range. However, a traceable product never replaces prior medical advice.
CBD is not a neutral product
A common misconception persists: because CBD is plant-based and sold freely, it is supposedly safe to combine with any medication. Cases reported by poison control centers and clinical trials of citalopram demonstrate the contrary. The real danger lies not in CBD itself, but in the silence surrounding its use when a healthcare professional is unaware of this information.
Three key actions summarize the essentials: always discuss it with your doctor or pharmacist, monitor for unusual symptoms in the days following the introduction of CBD, and be prepared to adjust or discontinue use if necessary. Your pharmacist remains the most accessible person to ask these questions on a daily basis.
— Fred
Traceable CBD products, to be used with medical advice
We select each oil, each flower and each resin for their traceability and compliance with French legislation, in an ethical approach focused on sustainability since 2018.
Our categories cover several needs and forms of consumption:
- CBD oils are practical for regular and gradual dosing.
- CBD flowers , sourced from our selection of organic hemp.
- CBD resins , for those already familiar with this format.
We make no therapeutic claims about our products: they are for well-being, not medical treatment. If you are currently undergoing treatment, speak to your doctor before ordering, and then explore our selection ofCBD oils to make an informed choice.
This article provides general information and is not a substitute for professional medical advice. Consult a qualified healthcare professional about your specific situation before taking any action based on this content.
Frequently Asked Questions
Which medications should not be taken with CBD?
Medications with a narrow therapeutic index present the most documented risk, particularly tacrolimus, warfarin, and clobazam. The ANSM (French National Agency for Medicines and Health Products Safety) recommends systematically informing your doctor about your CBD use if you are taking any of these medications.
Which medication should absolutely not be mixed with CBD?
Anticoagulants such as warfarin and immunosuppressants such as tacrolimus are among the most closely monitored combinations, as changes in their blood concentrations can have serious consequences. A systematic review confirms that these drugs with a narrow therapeutic index require close monitoring when used in combination with cannabinoids.
Which CBD should I choose for tendonitis?
The choice of product depends on your preferred use and should always take into account any current treatments, particularly anti-inflammatory medications. We recommend consulting a healthcare professional before combining any product, and then exploring our CBD oils or wellness products based on your needs.
Can CBD and paracetamol be taken at the same time?
Paracetamol is not among the drugs mentioned in pharmacovigilance alerts regarding interactions with CBD.
Sources
- Mixing CBD and medication is never harmless – ANSM
- Clinical study: CBD effect on citalopram and morphine pharmacokinetics – PMC
- Systematic review of drug-drug interactions of delta-9-THC and CBD – Frontiers (2024)
- Pharmacology of cannabidiol (technical document)
