The World Health Organisation released a report on CBD products in 2018.
In this report, they confirmed that CBD is considered safe to use for most people.
But there is one important caveat to this advice: CBD oil may interact with other medications.
What does this mean exactly?
There is the risk that CBD could alter the way your body metabolises medications, so it’s essential to be aware of this before adding any CBD products to your daily routine.
Since CBD is relatively new to the market, it might not be mentioned in the warnings and precautions section of your patient information leaflet.
It’s important to check with your GP or pharmacist if you’re wondering will CBD interact with medication – but the grapefruit rule is a good one to keep in mind.
This guide will explore how CBD can impact the metabolism of medications and how you can check if it is safe to use.
What's in this Guide?
What is CBD?
Before we can understand how CBD might interact with medications, we first have to understand how CBD interacts with the body.
CBD stands for cannabidiol. It is one of around 113 compounds extracted from the cannabis plant.
These compounds are called cannabinoids.
Cannabinoids are capable of interacting with the human endocannabinoid system. This is a system of receptors, neurotransmitters and enzymes that send messages between cells.
Endocannabinoid receptors are found in the central and peripheral nervous systems and systems such as the digestive system and the reproductive system.
You also have endocannabinoid receptors in your skin.
The body produces its own endocannabinoids, which send messages between cells and maintain balance in the body (homeostasis).
However, a faulty endocannabinoid system is thought to be why some individuals benefit from CBD supplements.
CBD is not identical to endocannabinoids, but it is thought to help reduce enzyme activity that breaks down endocannabinoids after they have done their job.
This boosts the level of endocannabinoids available.
What is CBD Oil Used For?
CBD is available in many different forms and is used for a variety of reasons.
It’s important to remember that CBD available over the counter and online is not a medicine; it’s a food supplement.
There are only two CBD-based medications available on prescription in the UK.
These are used to treat MS and rare forms of epilepsy and are not widely prescribed.
No other CBD product can claim to be a medicine or cure/treat conditions.
Instead, CBD is recommended as a way to support your endocannabinoid system and increase your overall sense of wellness.
CBD is commonly used by those looking for an alternative, holistic way to support their health and wellbeing.
CBD is also commonly used as a natural sleep aid, as drowsiness is one of the common side effects.
CBD may also be added to skincare products and other topical creams such as muscle rub.
And finally, it may be added to shampoo and nail care products, although their efficacy is still up for debate.
Will CBD interact with medication?
Yes, CBD products can interact with other medications. CBD can change the way your body metabolises medication, which could potentially alter its efficacy.
This could include prescription and over-the-counter medications.
It can also impact how your body breaks down other supplements and vitamins.
Before taking CBD products, it’s important to confirm that they will not interact with other medications.
How does CBD impact other medications?
To understand how CBD products can impact other medications, we first must understand how medications, supplements and vitamins are broken down in the body.
Every time you take a medication or supplement, your body has to break it down and eliminate it.
This happens throughout the body, starting in the gut and finally ending up in the liver.
A family of enzymes called cytochrome P450 (CYP450) are responsible for breaking down foreign substances and removing them from the body.
Your metabolism determines how fast this process takes.
Some substances can speed up or slow down how quickly you metabolise medications.
If you take longer to process a medication, then it can build up in your system.
And if you metabolise medications too quickly, it might not have enough time to be effective.
CBD inhibits CYP3A4, which is an important enzyme from the CYP450 family. The CYP3A4 enzyme is responsible for metabolising around 60% of prescribed medications.
So taking CBD with other medications can slow down the rate you break down and eliminate the medication. If this happens, you will have more medication in your bloodstream than you should have, even if you stick to your usual dose and schedule.
The reverse is also possible. Your body needs CYP3A4 to break down CBD, but some medications can inhibit this enzyme.
When this happens, CBD sticks around in your system for longer.
Is CBD oil safe to take with other medications?
As we’ve outlined above, CYP3A4 is responsible for metabolising around 60% of all prescribed medications.
So there is a good chance that it could interact with your medication.
CBD is thought to interact with the following types of medications:
- Antidepressants such as fluoxetine or Prozac.
- Medications that can cause drowsiness, such as antipsychotics and benzodiazepines.
- Macrolide antibiotics, including erythromycin and clarithromycin.
- Heart medications, including some calcium channel blockers.
- Heart rhythm medication, including amiodarone.
- Blood thinners, including warfarin.
- Thyroid medication, including levothyroxine.
- Seizure medications, including clobazam, lamotrigine, and valproate.
More research is needed to understand how CBD interacts with other medications, and there is clearly a lot of ground to cover.
For example, in one small scale study of 25 children taking clobazam for epilepsy, the 13 children given CBD alongside their medication were found to have higher levels of clobazam in their system.
Researchers determined it was safe but recommended close monitoring.
It could be a long time before researchers have determined which medications are safe to use with CBD, which require additional supervision, and which should not be mixed.
Until then, anyone taking other medications is advised to steer clear of CBD products until they have the all-clear from your GP or pharmacist.
Potential side effects too look for
If you decide to continue using CBD products under the close supervision of your GP, you should be aware of the following potential side effects.
If you notice any of these side effects, stop using your CBD.
- Increase in severity or new medication side effects, including:
- A decrease in the effectiveness of your medication
- Common CBD side effects and changes to these side effects, including:
- Change in appetite
- Weight changes
CBD oil and the grapefruit warning
A simple way to determine if your medication is likely to interact with CBD is to look for the grapefruit warning.
For example, suppose your medication recommends limiting your intake of grapefruit and other citrus fruits such as Seville oranges, pomelos and tangelos. In that case, there is a good chance it will interact with CBD.
If you choose to continue using CBD with other medications, it’s important to look out for changes in the side effects.
The following types of medication will commonly carry a grapefruit warning:
- Antibiotics and antimicrobials
- Anticancer medications
- Antiepileptic drugs (AEDs)
- Blood pressure medications
- Blood thinners
- Cholesterol medications
- Erectile dysfunction medications
- GI medications, such as to treat GERD or nausea
- Heart rhythm medications
- Mood medications, such as to treat anxiety, depression, or mood disorders
- Pain medications
- Prostate medications
If you are taking any medications listed above, it’s important to be aware of the potential for an interaction.
Pay close attention to side effects and how the medication makes you feel.
If there are any changes to the medical efficacy or you notice more extreme CBD side effects, stop taking CBD and check with your GP if it is safe to continue.
CBD skin creams, lotions, balms, shampoo and other topical products should not have the same impact, as little makes it into the bloodstream.
So, if you’re using CBD muscle balm for joint pain, you shouldn’t have any interactions with other medications.