Does CBD have contraindications? Yes. Although cannabidiol has a good safety profile and is well tolerated by most people, it is not suitable in every situation: it can interact with certain medications and is not advised during pregnancy, breastfeeding, in people with liver or heart disease, and in minors without professional supervision.
In this Cannactiva guide we review, with scientific references, what contraindications CBD has, who should not take it and how to reduce the risk of unwanted effects. Before you begin, it is worth knowing the different ways to consume CBD. Here we explain in which cases or when it is best not to use it.
CBD products, such as CBD oils, are not medicines or food supplements and, in most European countries, are intended for external use. This is an informational article and does not replace medical advice: if you have symptoms or are undergoing treatment, consult your healthcare professional.
In 30 seconds:
- CBD does have contraindications, but they are avoidable with proper use.
- The main risk is interactions with medications (anticoagulants, antiepileptics, antidepressants, sedatives…) via the liver's cytochrome P450 pathway.
- It is not recommended during pregnancy, breastfeeding, in minors, with liver or heart disease, or alongside chronic medication without consulting a doctor.
- Most safety warnings come from very high pharmacological doses (>1,000 mg/day), far above those of an over-the-counter CBD oil.
What is CBD?
Cannabidiol (CBD) is one of the main compounds in the hemp plant (Cannabis sativa). Unlike THC, it is not psychoactive: it does not produce a “high” or alter perception. The World Health Organization (WHO) concluded in its report on cannabidiol that CBD is generally well tolerated, with a good safety profile, and that it shows no signs of abuse or dependence in humans.
This does not mean it is harmless in every circumstance: like any bioactive substance, there are situations where its use is contraindicated, which is exactly what we look at below.
To start using CBD, it is usual to begin with a low concentration —such as a CBD oil at 2.5% or 5%, which lets you adjust the dose drop by drop— and to keep the higher concentrations for when you already know your tolerance. These are some of our most popular CBD oils and CBD flowers:
Who should not take CBD?
Although most healthy adults tolerate CBD well, some people should avoid it or check with their doctor first:
- Pregnant and breastfeeding women, due to a lack of safety data.
- Children and adolescents, except under professional direction and supervision.
- People with liver disease, because CBD is metabolised in the liver.
- People with heart conditions or who take heart medication.
- Those on long-term medication (anticoagulants, antiepileptics, antidepressants, sedatives…), because of possible interactions.
- Before driving or doing risky tasks, until you know how it affects you (it can cause drowsiness).
We detail each case below.
What contraindications does CBD have?
Like any substance, cannabidiol must be used properly to avoid adverse effects. It is worth clarifying from the outset that most safety warnings come from very high pharmacological doses (those used in medicines such as Epidiolex), not from the doses of an over-the-counter CBD product. These are the main contraindications of CBD:
CBD interactions with medications
CBD can interact with several medications because it is metabolised in the liver. Taking CBD drops alongside other drugs could change the way they work, increasing or decreasing their effects.
Specifically, CBD is processed in the liver by a group of enzymes called cytochrome P450. Since many medications use these same enzymes, both substances “compete” and CBD can alter the effectiveness of drugs such as anticoagulants, antidepressants or antiepileptics (4).
To understand it with an everyday example: grapefruit inhibits these same liver enzymes, which is why the leaflets of many medications warn against taking them with grapefruit juice. CBD works in a similar way: it competes for those enzymes and can alter the blood concentration of other drugs.
Drug group | Examples | Why caution |
|---|---|---|
Anticoagulants | warfarin, Sintrom® | CBD may change their blood levels |
Antiepileptics | clobazam, valproic acid | Increased metabolites / liver stress |
Antidepressants | fluoxetine, sertraline | Possible change in their concentration |
Sedatives / benzodiazepines | diazepam, alprazolam | May increase drowsiness |
We cover each case in our guides on CBD and anticoagulants such as Sintrom, CBD with ibuprofen and other NSAIDs and CBD with antidepressants. More detail in our guide on CBD and medications.
CBD during pregnancy, breastfeeding and childhood
The effects of CBD on fetal development and on newborns are still not fully understood, but given the influence of the endocannabinoid system (ECS) during pregnancy, it is advisable to avoid CBD during this stage.
CBD could affect the permeability of the placental barrier (5) and may also be excreted through breast milk, which is why it is not recommended during breastfeeding (6).
What happens if you take CBD during pregnancy or breastfeeding?
In children and adolescents, using CBD without professional advice is contraindicated. The endocannabinoid system is key to brain development, and introducing CBD can have unpredictable effects.
In addition, CBD products should be kept out of the reach of children to prevent poisoning (especially gummies).
CBD and liver disease
Since CBD is processed in the liver, when liver conditions are present its use is contraindicated without professional advice.
At high doses, CBD could affect liver function and raise liver enzymes, a sign of liver stress (1, 2, 3). This does not mean that CBD damages the liver in healthy people: in people without underlying conditions it need not cause problems at normal doses.
The risk increases when combining CBD and alcohol. If you use CBD, it is advisable to monitor liver function with a professional, especially at high doses or over long periods. More in the effects of CBD on the liver.
CBD, heart disease and hypertension
CBD can cause mild fluctuations in heart rate and blood pressure (7) which, although usually subtle, can affect people with heart conditions.
People with heart disease, especially those taking beta-blockers, should consult their doctor before taking CBD, as cannabidiol could enhance its blood-pressure-lowering effect.
CBD and hypertension: how does it affect blood pressure?
CBD and mental health disorders
In mental health disorders, the effects of CBD can be unpredictable. Although its role is being studied in schizophrenia and bipolar disorder (8, 9), more research is needed on its effect on symptoms and psychiatric medication.
Although CBD has become popular for anxiety and depression, in the case of mental health disorders it is best to always seek medical supervision.
Is CBD bad or dangerous? Is it addictive?
No. CBD is not toxic and is not a substance of abuse and, unlike THC, it does not produce a “high” or cause dependence: the WHO itself rules out any potential for abuse. Many of the problems attributed to it actually come from poor-quality products (mislabelled, with hidden THC or adulterated with synthetic cannabinoids), not from cannabidiol itself.
We explain this in detail in does CBD get you high? and in is CBD addictive?.
Adverse effects of CBD
CBD can have side effects that are infrequent and mild, such as changes in appetite, dizziness, diarrhoea, fatigue or dry mouth. They vary from person to person and with the dose.
These effects are usually mild and dose-dependent. We cover them in our guide on the side effects of CBD.
How to avoid the contraindications of CBD
Most problems can be avoided with three habits:
- Start with low doses and increase gradually (“start low, go slow”); see our guide to CBD dosage.
- Choose products with lab testing and clear labelling: quality is what most affects tolerance.
- Consult your doctor if you take medication, have a medical condition or are pregnant, and avoid driving until you know how it affects you (driving and CBD).
It is worth remembering that over-the-counter CBD products, such as CBD oils or flowers, are wellness products for external use and are not intended to prevent, treat or cure any disease.
Frequently asked questions about the contraindications of CBD
Which medications should not be taken with CBD?
Mainly anticoagulants (warfarin, Sintrom®), antiepileptics (clobazam, valproic acid), antidepressants, benzodiazepines and certain cardiovascular drugs, because they share the liver's cytochrome P450 pathway. Always consult your doctor.
Can I drive if I take CBD?
CBD can cause drowsiness, especially when starting out or at high doses. It is sensible not to drive until you know how it affects you. In addition, products with traces of THC could test positive in roadside checks.
Does CBD have serious side effects?
No serious effects have been documented at normal doses. When they do appear (drowsiness, dry mouth, diarrhoea, changes in appetite) they are mild, temporary and reversible.
Conclusion: is it safe to take CBD?
CBD has a good safety profile and most healthy adults tolerate it well. Even so, its use should be approached with caution in people with specific medical conditions. Many of the contraindications of CBD can be avoided with proper management and by consulting a doctor when taking other medication. You can see the balance between benefits and precautions in our overview of the medicinal properties of CBD.
And if you want to use it well from the start, take a look at our guide on how to consume CBD safely.
Note: this is an informational article and is not intended to prevent, diagnose or treat any disease. Cannactiva products are not medicines and are intended for external use. Consult your doctor before using CBD.
References
- Devinsky, O., Patel, A. D., Cross, J. H., Villanueva, V., Wirrell, E. C., Privitera, M., Greenwood, S. M., Roberts, C., Checketts, D., VanLandingham, K. E., Zuberi, S. M., & GWPCARE3 Study Group (2018). Effect of Cannabidiol on Drop Seizures in the Lennox-Gastaut Syndrome. The New England journal of medicine, 378(20), 1888–1897. https://doi.org/10.1056/NEJMoa1714631
- Devinsky, O., Patel, A. D., Thiele, E. A., Wong, M. H., Appleton, R., Harden, C. L., Greenwood, S., Morrison, G., Sommerville, K., & GWPCARE1 Part A Study Group (2018). Randomized, dose-ranging safety trial of cannabidiol in Dravet syndrome. Neurology, 90(14), e1204–e1211.
- Ewing, L. E., Skinner, C. M., Quick, C. M., Kennon-McGill, S., McGill, M. R., Walker, L. A., ElSohly, M. A., Gurley, B. J., & Koturbash, I. (2019). Hepatotoxicity of a Cannabidiol-Rich Cannabis Extract in the Mouse Model. Molecules (Basel, Switzerland), 24(9), 1694.
- Zendulka, O., Dovrtělová, G., Nosková, K., Turjap, M., Šulcová, A., Hanuš, L., & Juřica, J. (2016). Cannabinoids and Cytochrome P450 Interactions. Current drug metabolism, 17(3), 206–226.
- Feinshtein, V., Erez, O., Ben-Zvi, Z., Eshkoli, T., Sheizaf, B., Sheiner, E., & Holcberg, G. (2013). Cannabidiol enhances xenobiotic permeability through the human placental barrier by direct inhibition of breast cancer resistance protein: an ex vivo study. American journal of obstetrics and gynecology, 209(6), 573.e1–573.e15.
- Joseph, P., & Vettraino, I. M. (2020). Cannabis in Pregnancy and Lactation - A Review. Missouri medicine, 117(5), 400–405.
- Jadoon, K. A., Tan, G. D., & O'Sullivan, S. E. (2017). A single dose of cannabidiol reduces blood pressure in healthy volunteers in a randomized crossover study. JCI insight, 2(12), e93760.
- Pinto, J. V., Saraf, G., Frysch, C., Vigo, D., Keramatian, K., Chakrabarty, T., Lam, R. W., Kauer-Sant'Anna, M., & Yatham, L. N. (2020). Cannabidiol as a Treatment for Mood Disorders: A Systematic Review. Canadian journal of psychiatry. Revue canadienne de psychiatrie, 65(4), 213–227.
- Boggs, D. L., Surti, T., Gupta, A., Gupta, S., Niciu, M., Pittman, B., Schnakenberg Martin, A. M., Thurnauer, H., Davies, A., D'Souza, D. C., & Ranganathan, M. (2018). The effects of cannabidiol (CBD) on cognition and symptoms in outpatients with chronic schizophrenia a randomized placebo controlled trial. Psychopharmacology, 235(7), 1923–1932.
