Is CBD Oil Safe? Drug Interactions, Other Side Effects and Contamination-Risks

Is CBD Oil Safe to Use

If you want to use CBD oil, you might be concerned about its safety.

Is CBD oil safe to use?

The answer to this question might come as a surprise to you …

No, using CBD oil isn’t always safe!

The main health risks associated with using CBD oil are the following:

  • CBD oil can potentially interact with various pharmaceutical drugs, and;
  • CBD oil can be contaminated with pesticides, heavy metals, bacteria, mold, and residual solvents.

Today you’re going to learn about all the health risks associated with using CBD oil.

The best part?

You’ll learn exactly how to minimize these health risks.

CBD oil and Potential Drug Interactions

First, it’s important to emphasize that although CBD is associated with various health benefits

It’s also important to remember that:

CBD oil is not medicine. Currently, there’s no scientific evidence supporting the idea that commercially sold CBD products can cure or treat diseases or conditions. We strongly advise against using CBD oil for medical reasons.

That being said, if you’re on medication and interested in using CBD oil for general health reasons, it’s highly important that you understand that it can potentially interact with certain pharmaceutical drugs.

The potential drug interactions of CBD are mostly related to its nature to inhibit CYP450 enzymes, which have an important role in the metabolism of many drugs.

Drug interactions are often the result of complex biochemical processes and can be affected by various factors like:

  • Type of disease;
  • Patient conditions, and;
  • The nature of the compounds involved.

There are three (3) different potential outcomes of a drug interaction:

  • Additive (1 + 1 = 2);
  • Synergistic (1 + 1 > 2), or;
  • Antagonistic (1 + 1 < 2).

As you can see, it’s hard to predict the effects of drug interactions, especially in the case of synergistic or antagonistic drug interactions.

CBD oil and drug interactions

Clinical studies that looked at drug interactions of CBD are rare, but there are a few.

Looking at CBD’s mechanism of action that inhibits CYP450 enzymes, researchers hypothesized that using CBD oil with certain pharmaceutical drugs that get metabolized by these enzymes, could lead to unexpected adverse reactions.

Let’s take a closer look.

CBD and Cytochrome P450 (CYPs)

CYPs are a family of enzymes that have an important role in drug metabolism.

While CYPs help some drugs get deactivated and excreted from the body, they also help other drugs get activated to form their active compounds.

CBD has been shown to be a potent inhibitor of the following CYP450 enzymes: CYP2D6, CYP2C8, CYP2C9, CYP2C19, CYP2A4, and CYP3A4.

This means that CBD has the potential to:

  • Prevent or delay the catabolism (breaking down) of drugs that get metabolized by CYP450 enzymes, and/or;
  • Prevent or delay anabolism (synthesis) of drugs that get metabolized by CYP450 enzymes.

In medical terms, any drug that gets metabolized through these enzymes is called a ‘substrate’ of that particular enzyme.

Cocaine, for example, is a substrate of the CYP3A4 enzyme.

Researchers estimated that approximately 60% of clinically prescribed drugs are metabolized via CYP3A4.

This means high doses of CBD could block the metabolization of at least 60% of clinically prescribed drugs through its mechanism of action that inhibits the CYP3A4 enzyme.


Studies That Looked at Drug Interactions of CBD

One study done on mice found that CBD can delay the metabolization of cocaine. But what the study also found was that CBD only significantly decreased the metabolization of CYP substrate ‘cocaine’, when taken in extremely high doses off 30mg/kg.

Studies That Looked-at-Drug Interactions of CBD

While the effects of a particular dose of CBD can have different effects on animals compared to humans …

Such a high CBD dose is highly unrealistic with an average bottle of CBD oil. In some cases, taking 30mg/kg of CBD would mean clearing a full bottle of CBD oil in a single gulp.

Another study looked at the interactions of CBD and clobazam (CLB) in children with epilepsy. Clobazam is a benzodiazepine and is a traditional medicine used to treat epilepsy.

The researchers found that co-administration of cannabidiol (CBD) and CLB increased the level of CLB in the blood of children with epilepsy.

This could indicate that CBD delays/blocks the breaking down of CLB.

Patients in the study began taking CBD at a dose of 5 mg/kg/day and increased the dose by 5 mg/kg/day each week to a goal of 25 mg/kg/day.

CLB and CBD blood levels were measured at 4 weeks and 8 weeks into the study. After 8 weeks, CLB levels in the children were 2- to 6-times higher than what was expected if the children took CLB without CBD.

Human Studies-That-Looked-at-Drug-Interactions-of-CBD

As you can see, CBD can significantly increase drug blood-levels of drugs that get metabolized by CYP450 enzymes and the researchers note that monitoring CLB levels is necessary for clinical care of patients that take CLB and CBD at the same time.

That being said, the researchers conclude that:

CBD appears to be safe and effective in pediatric patients on CLB treatment for refractory epilepsy

Even though CLB-levels were significantly higher when CBL was taken with CBD, the combination was effective in improving epilepsy. And the reported side-effects, which include drowsiness and irritability, were all resolved with CLB dose adjustments. This indicates that the side-effects were probably CLB-related and not (directly) CBD-related.

This is just one example of a pharmaceutical drug that interacts with CBD.

Epidiolex: a CBD-containing Pharmaceutical Drug

There’s currently one FDA-approved, CBD-based prescription drug called ‘Epidiolex’. Epidiolex is basically purified CBD in an oral solution and is used for the treatment of epilepsy and can give us clues as to what drug interactions are possible when taking CBD oil.

The FDA has an in-depth document covering literally everything about Epidiolex.

What we can find in the document about drug interactions of Epidiolex is the following:

Epidiolex can interact with all ‘substrates’ of the following enzymes:

  • UGT1A9;
  • UGT2B7;
  • CYP1A2;
  • CYP2B6;
  • CYP2C8;
  • CYP2C,9 and;
  • CYP2C19.

In medical terms, any compound or drug that gets metabolized by these enzymes is called a ‘substrate’ of that particular enzyme.

For example:

  • theophylline and caffeine are substrates of CYP1A2;
  • bupropion and efavirenz are substrates of CYP2B6;
  • gemfibrozil, lamotrigine, morphine, and lorazepam are substrates of UGT2B7.

For a full explanation of potential drug interactions of Epidiolex, I refer you to the FDA document.

If you’re on medication and want to use CBD oil, always consult with your doctor first.


For a non-exclusive list of CYP substrates that CBD might interact with you can check out this list:

Again, if you plan to take CBD and are already on medication, please consult with your doctor before taking any CBD products.

Health Risks Associated with CBD Oil and Contaminations Risks

CBD Oil Contamination Risks

When it comes to CBD oil there are some very real contamination risks.

To understand these contamination risks, first, you have to understand on a basic level how CBD oil gets produced.

CBD oil is made from hemp plants.

The complete manufacturing-cycle of a CBD oil approximately looks like this:

  1. Starts as hemp seed;
  2. Grows into a fully-grown and flowering hemp plant;
  3. The hemp plant goes through an extraction process and various compounds get stripped from the plant resulting in a ‘raw’ or ‘crude’ hemp-extract;
  4. The ‘raw’ or ‘crude’ extract goes through a filtering process that filters out any unwanted compounds like plant lipids and waxes;
  5. After the filtering process, what’s left is a CBD oil containing CBD and potentially other hemp-derived compounds like THC and terpenes (the exact biochemical composition of a CBD oil is highly dependent on the botanical characteristics of the hemp strain, extraction-method and filtering-process).

From the moment the hemp seed gets planted, to the moment drops of CBD oil end up in your body, there’s a real risk of the product getting contaminated.

It starts literally from the moment a hemp seed gets planted in the soil.

Let me explain.

Hemp is a so-called ‘bio-accumulator’ plant. This means that hemp absorbs not only nutrients from the soil it’s cultivated in, but it also absorbs every other type of compound, including toxic heavy metals and other chemical waste. If you plant hemp seeds in toxic soil, the result will be toxic hemp plants.

Then, when the plant starts growing, hemp growers can also make use of pesticides to increase the yield of their plants. While these pesticides can be good for the growth and yield of a plant, they can be harmful to us. Pesticides get absorbed by the plant, and when you extract CBD out of a pesticide-filled hemp plant, you’re going to get the pesticides with it.

There are also safety concerns related to the use of the toxic solvents used to extract CBD out of hemp plants. Some CBD oil producers make use of toxic solvents like

In general, the following holds true:

When you extract CBD and other beneficial compounds from contaminated hemp plants, all these contaminants can get extracted at the same time. All these heavy metals, waste products, and pesticides can end up in your CBD oil.

In fact, various studies have found that CBD oils and the plants used to produce them, can be contaminated with synthetic cannabinoids, pesticides, and heavy metals.

For example, recently (2019) researchers found that a sample of commercially sold CBD oil contained the synthetic cannabinoid AB-FUBINACA. Synthetic cannabinoids have been associated with multiple deaths, dangerous side effects, and high toxicity.

Another study found that even though medical marijuana should undergo strict quality control measures, different samples of medical marijuana in California were contaminated with fungal infections.

Keep in mind that hemp that’s used to produce commercial-grade CBD oil, generally is subject to less strict quality control measures and we have every reason to think that fungi-contaminated CBD oils are a real risk.

If you’re wondering what happens to your health when you ingest a CBD oil that’s contaminated with synthetic cannabinoids, toxic heavy metal particles, fungi, and pesticides:

  • Synthetic cannabinoids have been associated with psychosis, seizures, and even death cases.
  • Ingesting heavy metals in large enough concentrations has been associated with cardiovascular, bone, kidney and nervous diseases.
  • Ingesting large concentrations of pesticides and/or ingesting them over long periods of time has also been associated with negative health effects, like an increased risk of cancer, reproductive issues, and mental health disorders.

As you can see, although CBD and other hemp-derived compounds can be beneficial to your health, ingesting contaminated CBD oil can do your health more harm than good.

Just when you thought you were doing something healthy (taking CBD oil), you could be doing the opposite (ingesting toxic contaminants large concentrations).

Besides these very impactful health risks, there are some lesser side effects that you could experience by taking CBD oil, which are possibly caused by CBD itself.

CBD Oil Side Effects

You already learned about the possible side effects of taking CBD oil when taken in combination with pharmaceutical drugs.

But there are also side effects associated with CBD itself, separate from its potential side effects through interactions with pharmaceutical drugs.

First, it’s important to note that although there are some CBD-related side-effects reported in different studies, in general, all CBD-related studies described a favorable safety profile of CBD in humans.

‘Favorable’ compared to what?

Well, for example:

Studies that looked at the effects of CBD on epilepsy and psychotic disorders found that CBD can be more effective, while having a better side effect profile, compared to traditional drugs used in the treatment of these conditions.

That being said let’s take a look at studies that (among other things) looked at the side effects of CBD.

Animal Studies

Most CBD studies done on animals found little to no side effects associated with the use of CBD.

For example:

In one study with rodents, CBD treatment of up to 14 days (3–30 mg/kg) did not affect blood pressure, heart rate, body temperature, glucose levels, pH, pCO2, pO2, hematocrit, K+ or Na+ levels, gastrointestinal transit, emesis, or rectal temperature in a study with rodents.

In another study, mice treated with 60 mg/kg CBD for 12 weeks (three times per week) did not show ataxia, kyphosis, generalized tremor, swaying gait, tail stiffness, changes in vocalization behavior or open-field physiological activity (urination, defecation).

Human studies

Before we start looking at studies that found side-effects associated with the use of CBD, most studies done on humans found little to no side effects associated with the use of CBD.

For example:

Two studies already done in 1973 found that oral CBD (15–160 mg), iv injection (5–30 mg), and inhalation of 0.15 mg/kg CBD did not lead to adverse effects. Psychomotor function and psychological functions were also not disturbed.

Treatment with up to 600 mg CBD neither influenced physiological parameters (blood pressure, heart rate) nor performance on a verbal paired-associate learning test.

In an FDA Public Meeting on Safety of CBD, different in-vivo studies were reviewed to look for potential CBD side-effects.

The results can be seen below:

Studies that show side effects of CBD


A review study done in 2011 by Bergamaschi et al. that reviewed 132 CBD-related studies found that several studies suggested that CBD had a relatively safe side-effect profile:

  • CBD is non-toxic in non-transformed cells;
  • CBD does not induce changes on food intake;
  • CBD does not induce catalepsy;
  • CBD does not affect physiological parameters (heart rate, blood pressure and body temperature);
  • CBD does not affect gastrointestinal transit, and;
  • CBD does not alter psychomotor or psychological functions.
  • Chronic use and high doses of up to 1500 mg per day have been repeatedly shown to be well tolerated by humans.

That being said, let’s take a look at some studies done on humans that did find side-effects associated with the use of CBD.

One Dutch study that compared adverse effects of three different strains of medicinal cannabis, found that all strains, including the high-CBD strain, produced “fatigue”. Since the low-CBD strains produced the same side effect, we can’t be sure that fatigue was specifically CBD’s side effect, but we can’t rule it out either.

A study that was done in 1980 that looked at the effects of chronic CBD-use on healthy volunteers and epileptic patients. 4 out of 8 epileptic patients remained completely free of convulsive crises, and 3 out of partially improved their condition. The only side-effect reported by 3 healthy volunteers and 4 epileptic patients was sleepiness/drowsiness.

A more recent study done in 2018, looked at the effects of long-term CBD-treatment in 264 Dravet syndrome patients (a form of therapy-resistant epilepsy). The average treatment-duration was 274 days with an average dose of 21 mg/kg/d of CBD.

Negative side effects occurred in 93.2% of patients with the most common ones being mild or moderate:

  • Diarrhea;
  • Pyrexia;
  • Decreased appetite, and;
  • Sleepiness/drowsiness.

CBD Side Effects Studies

Important to note here is that almost all patients were using traditional antiepileptic medications during this time. Therefore, it’s hard to tell which side-effects can be attributed to:

  • CBD;
  • Traditional antiepileptic medications, or;
  • Interactions between CBD and traditional antiepileptic medications.

There were also more severe side effects which the researchers attribute to potential interactions of CBD with these traditional antiepileptic medications. Some of these more severe side effects include:

  • Status epilepticus;
  • Liver function abnormalities;
  • Increase of certain liver enzymes;
  • Convulsion, and;
  • Severe pyrexia.

Again, when you’re on medication, we see how important it is to consult with a licensed physician/doctor before you decide to use CBD oil.

How to Minimize Health Risks Associated with CBD

To sum up:

The biggest health risks associated with the use of CBD are related to:

  • Potential interactions with pharmaceutical drugs, and;
  • Contamination risks of low-quality and untested CBD products.

How you avoid potential interactions with pharmaceutical drugs when taking CBD is by ALWAYS consulting with a licensed physician/doctor before taking CBD products like CBD oil.

CBD is a known inhibitor of CYP450 enzymes. Researchers estimated that approximately 60% of clinically prescribed drugs are metabolized by CYP450 enzymes. This means that CBD can block/delay the metabolization of MANY pharmaceutical drugs.

How you avoid contamination-risks when using CBD products like CBD oil is by making 100% sure that your CBD product is free of contaminations. And how you do that is by checking whether the CBD oil comes with independently-conducted lab-test reports by accredited lab-test facilities.

These lab-test reports should contain the following elements:

  • A potency test (a cannabinoid-test and preferably also terpene-test)
  • A pesticide test;
  • A heavy metal test, and;
  • A microbiological test.

And better would be if these test reports are available on a batch-by-batch basis.

How to minimize Health risks Associated with CBD


Even if you have aren’t on medication and have a 100% clean CBD oil, you can still experience side effects when using CBD oil.

Different studies found the following side effects associated with the use of CBD:

  • Diarrhea;
  • Pyrexia;
  • Decreased appetite, and;
  • Sleepiness/drowsiness.

While these side-effects can be inconvenient and in rare cases lead to life-threatening situations (feeling drowsy while driving a car for example), there seems to be a scientific consensus that CBD has a relatively safe side-effect profile.

What’s Next …

If you want to dive deeper into the science of CBD, we have several articles which explain in layman’s terms, the potential benefits of CBD.

You can find these potential benefits (backed by scientific research), here:

Just realize that CBD oil is not a medicine and it’s not intended to diagnose, treat, cure, or prevent any disease. Always consult with your doctor/physician before starting to use any of these products, ESPECIALLY if you’re already on medication. CBD oil can potentially interact with many pharmaceuticals.

If you’re looking for a CBD oil, it’s CRUCIAL that you get a CBD oil that’s 100% free of contaminants and contains therapeutic amounts of CBD. Check the article below to find:

If you want to learn the best ways to use and dose CBD oil, check out our guide on:

If you’re interested in vaping CBD, check out our list of:

If you’re interested in a more convenient (but less potent) way to use CBD, check out our list of:

If you have pain issues and want to understand the biology and science behind using CBD oil for pain, the following article is for you:

If you have anxiety issues and want to understand the biology and science behind using CBD oil for anxiety, the following article is for you:

Lastly, if you want to share this CBD  knowledge, click the links below OR if you want to connect with us, click the links below that to go to our Facebook or Instagram pages.

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