Can You Overdose on CBD Oil? How Much Is Too Much?

An illustration of a mouth taking CBD soft gel capsules
Written by Nina Julia | Last updated: July 30, 2021

“Can you overdose on CBD?”

It’s natural for people new to CBD to ask this question. After all, anyone who wants to try CBD will want to know if it’s really safe (even in large doses), as studies and many consumers say.

So, to answer the question — no, you won’t lethally overdose on CBD, but it is possible to take too much and feel uncomfortable for a few hours.

This article talks about the safety of CBD, what happens when you’ve taken too much, and what you can do to relieve some of the discomforts.

Why Can’t CBD Cause a Lethal Overdose?

Overdose is when you’ve taken more than the recommended dosage of a drug or a medication. If the signs of a drug overdose are ignored, it can lead to comatose or death.

The symptoms of an overdose vary, depending on the drug you’ve taken. These include:

  1. Changes in breathing pattern with difficulty breathing
  2. Changes in heart rhythm (cocaine increase heart rate, while opioids decrease heart rate)
  3. Severe headaches
  4. Nausea and vomiting
  5. Chest pain
  6. Agitation
  7. Severe anxiety

CBD doesn’t significantly inhibit the brainstem like opioids, for example. The brainstem is the part of the brain that houses the control centers for our heartbeat, blood pressure, breathing, body temperature, and digestion. 

High amounts of opioid-based drugs can cause an overdose since the brainstem contains many opioid receptors. Overstimulation of these receptors slows down our breathing and heartbeat.

Now, cannabinoid receptors are also abundant in the brain and the spinal cord, but studies show that the lower brainstem contains only a few cannabinoid receptors. So, even if you take high CBD doses, there won’t be enough cannabinoid receptors to activate and significantly affect our physiological parameters.

This is one of the reasons why high concentrations of CBD (and even THC) won’t result in an overdose.

CBD also has a weak affinity for the CB1 receptor to trigger any hallucinogenic or psychoactive effects like THC. CBD has not been shown to increase anxiety or cause delusion, paranoia, and other adverse side effects associated with THC.

Instead, CBD works on other receptors such as the serotonin and vanilloid receptors and helps modulate these negative reactions from THC.

What are the Effects of Too Much CBD?

Taking too much CBD may not result in fatal overdose and death, but it doesn’t mean that it won’t cause any discomfort.

CBD, just like any other drug, also has some side effects.

Taking too much CBD may cause:

  • Dry mouth. When CBD activates the cannabinoid receptors found in the mouth, it decreases saliva secretion.
  • Drowsiness, lightheadedness, and dizziness. These may be caused by CBD lowering the blood pressure since it relaxes the blood vessel walls.
  • Loose bowel movements or diarrhea
  • Appetite changes
  • Nausea and vomiting, especially on high CBD doses.

CBD also interacts with other drugs and may either increase or decrease their effectiveness. 

Take warfarin, a common blood thinner medication, for example. CBD boosts warfarin’s effect. It binds to the enzymes that break down warfarin, allowing the drug to stay in the system longer.

CBD may also enhance the effects of antiepileptic drugs like phenytoin as well as clobazam.

If you’re taking maintenance medications, we recommend speaking with your doctor about using CBD. Your primary care physician can give you advice on CBD use and whether or not it will have an impact on your other medications.

Your doctor can also help you manage your CBD use, including its dosage and frequency of use.

How Much CBD is Too Much CBD?

What’s the lethal or toxic dose of CBD?

Well, there’s no clear-cut answer to this yet.

However, a 2011 study showed that chronic CBD use of 1,500 mg per day — this is equivalent to taking a whole bottle of high potency CBD — was well-tolerated by patients with treatment-resistant schizophrenia. The patients also reported no significant side effects while on this high CBD dose.

In 2018, a study was also conducted on CBD’s tolerability and safety. It showed that CBD at increasing doses between 1,500 and 6,000 mg was still well-tolerated by the participants.

Some side effects were noted, like diarrhea, drowsiness, headache, and nausea, but these were pretty mild and tolerable.

Is CBD Safe?

The World Health Organization stated in a 2018 report that CBD is a non-psychoactive cannabinoid that’s generally well-tolerated by consumers and has a good safety profile. The report also stated that CBD doesn’t negatively impact our physiological parameters and may even have an opposite influence on THC’s psychoactive effects.

Can CBD Make Me Sick?

CBD won’t make you sick, but it can trigger some nausea and cause you to vomit in high doses. However, these are common high CBD dose side effects that typically go away after several hours.

Although rare, some people also develop allergies after taking CBD, so if you’re allergic to cannabis and pollen, you should be careful in using any cannabinoid-based product, including CBD.

How Long Does CBD Effects Last?

woman taking a CBD oil using a dropper

The effects of CBD can last anywhere from two to eight hours, but this depends on many factors.

Method of Administration

Sublingual CBD, like oils and tinctures, and inhalable forms like CBD flowers and vapes have a shorter duration than CBD edibles. The former typically lasts about two to four hours, while the latter lasts about six to eight hours.

Age and Metabolism

Your age and metabolism also affect how long CBD stays in your system. The older you are and the slower your metabolism is, the harder it will be for your body to process and get rid of CBD. 

CBD Potency and Frequency of Use

The higher the potency and frequency of use, the longer you’ll feel the CBD effects since CBD builds up in the system.

How to Get Rid of CBD Side Effects

The side effects of CBD are generally mild and tolerable, but if they become too uncomfortable, then follow these tips:

  1. Drink plenty of fluids to help relieve dry mouth and satiate your thirst.
  2. Rest if you’re feeling lightheaded and dizzy. These side effects may be due to the lowered blood pressure, and sitting or lying down helps improve blood circulation in the brain.
  3. Take your CBD oil with food. Using CBD on an empty stomach increases the chances of negative side effects. 

Should the side effects continue or even worsen, see your doctor. There may be some other underlying medical problems causing these issues, and these need to be addressed first before you can take CBD.

Contraindications to Taking CBD

It’s safe to take CBD daily, but you may want to rethink your decision to use CBD if you have the following conditions.

Hypotension or Low Blood Pressure

CBD dilates and relaxes the blood vessel walls, resulting in a drop in blood pressure.

If you’re hypotensive, high CBD doses can further lower your blood pressure and trigger drowsiness and dizziness.

Liver Problems

The liver processes and metabolizes the drugs we take, including CBD.

If you have liver problems, high doses of CBD and its accumulation in the bloodstream may be taxing to the liver. The unnecessary demand on the liver may even trigger some unwanted effects.

Pregnant and Breastfeeding Women

Cannabinoids, including CBD, can cross the placental barrier and negatively impact the growing fetus’s development. It can also be passed through the breastmilk and affect the baby.

Again, we emphasize the importance of seeing your doctor before taking CBD, especially if you have chronic health problems and are taking maintenance medications.

How to Minimize CBD Risks

CBD may have a good safety profile, even in very high doses, but there are ways to reduce the risk of developing side effects.

  1. Always choose quality CBD products — look for their certificate of analysis or laboratory test results. This shows you the potency and purity of the product. The COA also shows proof that it’s free from contaminants.
  2. Start low and go slow, especially if you’re new to CBD — Listen to your body as well, and reduce the dosage if you develop some adverse side effects. Be patient, and you’ll soon find the best dosage.
  3. Ask your doctor first if you’re taking any medications or have underlying medical conditions.

Final Thoughts: No, You Won’t Overdose on CBD

In summary, CBD won’t cause an overdose even if you take a higher dose since few cannabinoid receptors in the lower brainstem. CBD won’t slow down your breathing or affect your heart rhythm.

CBD is a safe and effective cannabinoid, and even if you do develop some side effects, these are generally mild and well-tolerated.

While there are ways to minimize CBD’s side effects, know that these usually resolve on their own once the effects of CBD wore off. However, if you have some chronic health problems, are on maintenance medications, or begin experiencing severe side effects on CBD, then we recommend seeking your doctor’s advice.

Have you tried high-dose CBD? How was it?

We’d love to hear about your experience, so leave your comment below!

References Used In This Article

  1. Herkenham, M., Lynn, A. B., Little, M. D., Johnson, M. R., Melvin, L. S., de Costa, B. R., & Rice, K. C. (1990). Cannabinoid receptor localization in the brain. Proceedings of the National Academy of Sciences of the United States of America, 87(5), 1932–1936. 
  2. Zlebnik, N. E., & Cheer, J. F. (2016). Beyond the CB1 Receptor: Is Cannabidiol the Answer for Disorders of Motivation?. Annual review of neuroscience, 39, 1–17. 
  3. Zlebnik, N. E., & Cheer, J. F. (2016). Beyond the CB1 Receptor: Is Cannabidiol the Answer for Disorders of Motivation?. Annual review of neuroscience, 39, 1–17. 
  4. Prestifilippo, J. P., Fernández-Solari, J., de la Cal, C., Iribarne, M., Suburo, A. M., Rettori, V., McCann, S. M., & Elverdin, J. C. (2006). Inhibition of salivary secretion by activation of cannabinoid receptors. Experimental biology and medicine (Maywood, N.J.), 231(8), 1421–1429.
  5. Grayson, L., Vines, B., Nichol, K., Szaflarski, J. P., & UAB CBD Program (2017). An interaction between warfarin and cannabidiol, a case report. Epilepsy & behavior case reports, 9, 10–11. [1]
  6. Bergamaschi, M. M., Queiroz, R. H., Zuardi, A. W., & Crippa, J. A. (2011). Safety and side effects of cannabidiol, a Cannabis sativa constituent. Current drug safety, 6(4), 237–249. [2]
  7. Taylor, L., Gidal, B., Blakey, G. et al. A Phase I, Randomized, Double-Blind, Placebo-Controlled, Single Ascending Dose, Multiple Dose, and Food Effect Trial of the Safety, Tolerability, and Pharmacokinetics of Highly Purified Cannabidiol in Healthy Subjects. CNS Drugs 32, 1053–1067 (2018). [3]
  8. World Health Organization. (2018). Cannabidiol (CBD): Critical Review Report. Expert Committee on Drug Dependence Fortieth Meeting Geneva, 4-7 June 2018. 
  9. Davis, E., Lee, T., Weber, J. T., & Bugden, S. (2020). Cannabis use in pregnancy and breastfeeding: The pharmacist’s role. Canadian pharmacists journal: CPJ = Revue des pharmaciens du Canada: RPC, 153(2), 95–100. [9]

Nina created CFAH.org following the birth of her second child. She was a science and math teacher for 6 years prior to becoming a parent — teaching in schools in White Plains, New York and later in Paterson, New Jersey.

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