How can CBD interact with medications?

¿Cómo puede interaccionar el CBD con los medicamentos?

As medical cannabis has gained significant attention in recent years, it is important to understand: CBD also affects the metabolism of drugs , varying their effects on our body.

Pharmacokinetics ethics

To understand how and why CBD can interact with medications , it is necessary to know the different processes that a drug undergoes during its passage through our body, something known as pharmacokinetics and consists of the following steps:

Absorption, or the process by which a drug passes into the bloodstream
Distribution of the drug to the places where it will produce its action
Metabolism
Elimination

This can change the bioavailability of the drug , that is, the amount of drug that remains in our body, thus causing a different effect than expected.[1]

It all depends on the form of administration

The way CBD is administered will also influence whether or not drug interactions occur, as the mode of administration affects the amount of CBD that can be present in the liver and how quickly it gets there. [2]

Topical route . Although topical cannabinoids can be absorbed through the skin and into the joints, they do not enter the bloodstream in this case. There is no potential for drug interactions to occur using this route . [2]

To learn more about the routes of administration you can take a look at our article , reviewed by the Neuropsychologist and Phytotherapist, Tommaso Bruscolini. We'll go into more detail later!

Inhibitory effect

It can increase its toxicity and the risk of suffering adverse effects .[3][4] Adjust the dose . This fact can also be used to our advantage. The same therapeutic effects can be achieved with lower doses of medication , resulting in fewer drug-related side effects and a higher quality of life.

Inducing effect

If CBD exerts an inducing effect on the enzyme responsible for the metabolism of a drug, the activity of the enzyme is enhanced . [3] [4] This causes our drug to be metabolized faster . If the amount of drug is less than expected, its effects are diminished. Therefore, the desired therapeutic effects may not be achieved . [3] [4] If we are taking a medication that interacts with CBD in this way, we would have to consult a doctor to readjust the dose . Appropriate administration routes can also be used to avoid these interactions , such as the correct use of the sublingual route or the inhaled route. [5]

Synergistic effect

CBD can also act synergistically with some drugs such as opioids. As a result, additive effects are obtained, greater than those achieved if the drug is administered alone. [3] [4] In this case, the effects of the drug are enhanced, so the same effect can be achieved with a lower dose . The exact mechanism by which this happens is still unknown. However, it is believed that it may be because both substances achieve the same effect in our body, despite activating different processes, hence the synergy. [3] [4] If a synergistic effect occurs, the same effect can be achieved with a smaller amount of medication , so it is recommended to consult a doctor to readjust the dose.

Non-steroidal, such as:

Ibuprofen
Diclofenac
Naproxen
Some drugs for arthritis

They are mainly metabolized by the enzymes CYP2C9 and CYP2C19. [3] This cannabinoid has a slight inhibitory effect on them, meaning it inhibits the metabolism of these drugs through CYP450. The drugs remain circulating in the bloodstream and could cause an overdose or toxicity . [3] If you are going to consume any of these drugs along with CBD, it is recommended to consult with a doctor to reduce the dose and monitor adverse effects and toxicity. Alternative administration routes may also be considered , such as correct use of sublingual or inhalation.

CBD and painkillers (Opioids)

Many of the painkillers we commonly take for pain relief are opioids. Some examples are:

Morphine
Methadone
Oxycodone
Codeine
Tramadol (Studies are needed to understand the interaction)
Fentanyl (Studies are needed to understand the interaction)

Some of them, such as codeine or oxycodone , have to be converted into other molecules to exert their effect on our body. This conversion is carried out by enzymes from the UGTs family. [5] CBD is an inhibitor of UGTs enzymes , so the analgesic effects of codeine or oxycodone will be less if consumed together with CBD. However, many studies show that cannabis increases the effect of opiates, but why? In some cells, there is a protein called P-gp, which is responsible for expelling some substances to the outside. Morphine and methadone are some examples. This causes the amount of opioids that enter our brain to be lower. It has been observed that CBD inhibits this protein, allowing greater amounts of morphine to enter the cells . This fact could be the explanation for the synergistic effect , which would explain the greater effect of opioids with lower doses if they are consumed together with CBD. [6] Opioids such as fentanyl or tramadol are not substrates of the P-gp protein. The effects of CBD on these drugs are still unknown. Therefore, further studies are needed. [6] The use of CBD together with some opioid analgesics does not increase the risk of suffering adverse effects. In fact, the same effect can be achieved with lower doses of the drug . [7] You may consult a doctor to readjust the dosage. For opioids such as fentanyl or tramadol, whose interactions with CBD are not yet fully understood, consult your doctor or use alternative routes to ingestion to avoid any possible effects.

CBD and painkillers (non-opioids)

Paracetamol (acetaminophen) is another commonly used analgesic* medication, but it is not an opioid. It is metabolized by enzymes known as UGTs . [6] * Fun fact : The analgesic effect of paracetamol is due to an indirect activation of cannabinoid receptors (CB1). [8] CBD is an inhibitor of UGTs enzymes , so the concentration of paracetamol in our body will be higher . This causes an increased risk of side effects, such as liver damage. [6] It is recommended to reduce the dose of the drug to reduce this risk, always consulting with medical advice . Other routes of administration other than ingestion may also be considered.

CBD and flu medicines

Some anti-flu medications commonly used to relieve cold symptoms use doxylamine as the main ingredient , an antihistamine that is also frequently found in allergy medications. CBD has an inhibitory effect on the enzymes that break down these medications. Consuming them simultaneously can produce an increase in the amount of the drug thus causing an increase in adverse effects such as; drowsiness, confusion and, in more severe cases, deterioration of motor function. [11] The best option is to adjust the dose to reduce the risk of adverse effects . Seek medical advice and consider other routes of administration other than the one ingested.

CBD and hormonal contraceptives

There are different opinions about the results of consuming CBD alongside hormonal contraceptives, so further study is still required on this subject. There are currently several clinical trials underway to assess the potential interactions of birth control pills with CBD. However, so far, the literature only provides information on how the whole cannabis plant (including CBD and THC, and not separately) may affect these preparations. If you want to know more about how THC interacts with medications, you can take a look at the article on drug interactions or the training video by Dr. Sarah Chinelo on the same subject. Literature: