CBD and anaesthesia: what to tell your team before surgery
Before an anaesthetic, tell the anaesthetist that you use CBD, and give the type of product, the amount, the frequency, how you take it and when you last took it. The US society ASRA Pain Medicine has recommended this since 2023; for lack of evidence, it takes no position for or against stopping beforehand. Neither stop nor carry on without discussing it, since the decision lies with the medical team. This article reports the state of research and does not replace medical advice.
Key takeaways
- In 2023, ASRA brought together 13 experts, who published 21 recommendations on cannabis and cannabinoids around surgery.
- Their first request is that every patient be asked about their use before the operation.
- With no data to go on, they recommend neither for nor against tapering before surgery.
- The sedation studies concern cannabis in general; none of them isolated CBD.
- The Epidyolex product information lists no interaction with an anaesthetic, and midazolam exposure is unchanged.
What US anaesthetists have recommended since 2023
The reference text is a consensus from ASRA Pain Medicine, the American Society of Regional Anesthesia and Pain Medicine, published in 2023 in Regional Anesthesia and Pain Medicine. A committee of 13 experts (anaesthetists, pain physicians and a patient representative) examined 9 questions. To be adopted, each recommendation needed at least 75% agreement under a modified Delphi method, in which experts vote over several rounds.
This produced 21 recommendations. According to ASRA's announcement, the first is to ask all patients about their use before surgery. For a CBD user, the other relevant points are these:
- With no data available, the experts can recommend neither for nor against tapering before the operation.
- If acute cannabis intoxication has impaired the patient's mental state, planned surgery should be postponed.
- After smoking cannabis, wait at least two hours before the procedure, because of a higher cardiac risk.
- Regular users may have more pain and nausea after surgery and need more painkillers, opioids included.
These recommendations cover cannabis and cannabinoids in the broad sense. The two-hour delay applies to smoked cannabis; a CBD oil is outside its scope.
What the anaesthetist needs to know
The experts name five pieces of information to collect, adapted to a CBD product in the table below. If you bring the packaging or the certificate of analysis to the consultation, most of the questions are settled.
| Information | Example for a CBD product |
|---|---|
| Type of product | Flower, resin, oil, with the stated CBD and THC content |
| How you take it | Smoked, vaporised, under the tongue, swallowed |
| Amount | Grams per day, or drops and milligrams of CBD |
| Frequency | Daily, weekly, occasional |
| Last use | Date and time |
THC content counts. A compliant flower holds no more than 0.30%, but a mislabelled product may hold more, or contain synthetic cannabinoids. To find those lines, see our guide to reading a certificate of analysis.
What studies on sedation show
The data available concern cannabis users, mostly of products rich in THC or of unknown composition. No study looks at CBD on its own.
| Study | Patients | Main result |
|---|---|---|
| Twardowski et al., 2019 | 250 records, endoscopy | Higher sedation needs in regular users (p = 0.05) |
| Nasser et al., 2024 | 419 patients, endoscopy | More often 5 mg of midazolam or more during upper endoscopy, not during colonoscopy |
| Smith et al., 2024 | Endoscopy | More propofol, with no difference in recovery time |
| Ekrami et al., 2024 | 34,521 surgical patients, 1,683 of them users | 30% more opioids in the 24 hours after surgery |
The 2019 study came from a single centre and a single endoscopist, and its result sits at the edge of significance. The gap persisted after adjustment for age, sex and use of alcohol, benzodiazepines and opiates. Among 419 patients, the 2024 prospective study found no more adverse events or discomfort in users. The 2024 replication concludes that use should be discussed before any sedation.
The largest cohort comes from Cleveland Clinic. Among 34,521 adults operated on between 2010 and 2020, the 1,683 cannabis users received 30% more opioids than non-users in the 24 hours after surgery. Their pain scores were slightly higher. The study found no link with respiratory complications. A 2025 review takes stock: the association between cannabis and higher propofol doses recurs from one study to the next, without proof of cause and effect.
What the Epidyolex product information says about interactions
On CBD alone, the most reliable source is the summary of product characteristics of Epidyolex, published by the European Medicines Agency. Epidyolex is the only authorised cannabidiol medicine, and the document describes what is established at medicinal doses.
Cannabidiol is broken down by, among others, three enzymes of the UGT family (UGT1A7, UGT1A9, UGT2B7). In vitro data show it inhibits the CYP2C19 enzyme, which can raise the concentration of medicines that this enzyme breaks down, such as clobazam or omeprazole. With clobazam, the active metabolite rises 3- to 4-fold. CBD can also increase exposure to medicines taken by mouth and carried by P-glycoprotein, such as everolimus, tacrolimus or digoxin. Alcohol and other central nervous system depressants can also add to drowsiness.
No anaesthetic appears among the interactions the product information lists. In an interaction study, cannabidiol did not change exposure to midazolam, a sedative commonly used in anaesthesia. Saying that CBD alters the effect of anaesthetics would therefore be an extrapolation. Our articles on drug interactions and on liver enzymes go into these mechanisms.
And in France?
We found no recommendation from the French Society of Anaesthesia and Intensive Care (SFAR) devoted to cannabis or CBD around surgery. This finding comes from our literature search and does not prove that none exists.
The pre-anaesthetic consultation, held before planned surgery, is the time to mention everything, including products bought without a prescription. The question of your last use arises as it would for a drug test, and our article on how long CBD stays in the body gives orders of magnitude. In pregnancy, our article on CBD during pregnancy and breastfeeding calls for the same caution.
Frequently asked questions
For lack of evidence, the 2023 US guidelines take no position for or against tapering before surgery. They ask for use to be reported. The decision lies with your doctor and your anaesthetist.
The type of product, how you take it, the amount, the frequency and the date you last took it. The packaging or the certificate of analysis, which give the CBD and THC content, answer most of these questions.
The EU product information for Epidyolex describes no interaction with an anaesthetic, and midazolam exposure stays the same. It does establish that CBD inhibits CYP2C19 in vitro and can add to drowsiness with other sedatives, which is reason enough to report it.
Tell the team before the procedure. The 2023 guidelines recommend delaying planned surgery by at least two hours after smoking cannabis, because of the cardiac risk. A compliant flower contains little THC, but the team should be the one to judge.
No. CBD sold in shops is not a medicine. The only authorised cannabidiol product, Epidyolex, is prescribed for certain epilepsies. After surgery, the medical team manages pain.
Written by the Phytogrammes team
Each journal article draws on cited primary sources: ANSM, EFSA, EUR-Lex and peer-reviewed publications. Product profiles are distinguished from documented laboratory results. Our approach.
Article published on . CBD is not a medicine.