CBD is a non-intoxicating cannabinoid with an excellent safety record. However, as with many supplements, consuming too much can produce adverse effects.
In most cases, taking too much CBD will produce only mild side effects, but at very high levels, it can become toxic and could produce an overdose.
CBD overdose - Fast facts
Too much CBD might result in drowsiness, stomach discomfort, nausea and diarrhea.
Guidance from the FSA states that adults should only use up to 70mg of CBD per day.
Taking 16,000mg of CBD in 24 hours is considered to be toxic to the liver.
What happens if you take too much CBD?
According to the World Health Organization, "CBD is generally well tolerated with a good safety profile". However, it can produce some side effects and interacts with some medications.
The risk of these side effects is likely to increase if you use a larger serving. Studies indicate that too much CBD may, for some people, result in drowsiness, stomach discomfort, nausea, and diarrhoea.
It’s also important to be aware that CBD is a biphasic substance, which means it produces two distinctive results when taken in different amounts. Small servings of CBD are more suited to daytime use and larger quantities are best for use in the evening. Consequently, the amount you take will affect the results you experience. If you're hoping for a mild result but take too much, you may experience effects that you were not expecting.
In 2019, a child was admitted to the hospital after being found unresponsive. Doctors discovered that he had eaten CBD. The initial tests indicated that he had consumed a large amount of THC. He fully recovered in 72 hours. When they tested the product he had taken, the results showed only tiny traces of THC.
In 2020 a 56-year-old man was hospitalised after taking a total of 370mg of CBD from two packets of gummies. He experienced slurred speech and vomiting and had completely recovered by the next day.
While both these incidents are not entirely explained, they indicate that while taking too much CBD or overdosing on CBD is unlikely, it's not impossible. They also raise the point that it's essential to only get CBD from trustworthy retailers (the 56-year-old man purchased his from a petrol station) that display their CBD and THC content clearly and have it backed up by third-party lab results.
Can you overdose on CBD?
According to Drugwise, an overdose is when "a person takes more than the medically recommended dose of a drug or more than their body has developed a tolerance for."
The symptoms of an overdose vary depending on the substance that caused the overdose. However, some can result in death; "Deaths from an overdose may be from heart failure (where the heart rate is slowed or stopped), liver failure (where the body is unable to eliminate the drug fast enough leading to poisoning) or respiratory failure."
CBD overdose is extremely unlikely and there are no recorded cases of anyone dying from taking too much CBD. Studies conducted with monkeys found that daily amounts of up to 300mg per kg of body weight increased the size of the animals' liver and kidneys but had few other effects. One piece of research stated that 20,000mg of CBD is considered to be toxic, but it hasn't been tested or observed in humans.
A recent investigation reported that CBD might damage the liver if taken in extremely high amounts. 50mg per kg of body weight, the equivalent of 4,000mg for an 80kg adult, may produce liver swelling and damage. At 200mg per kg of body weight, 16,000mg for an 80kg adult, the liver will likely develop signs of toxicity.
Can you overdose on THC from CBD products?
Some CBD products contain tiny traces of the intoxicating cannabinoid THC. In the UK, the legal limit for THC is 1mg per container. At this level, it will not get you high and you would have to consume enormous amounts of CBD oil or similar products to experience any THC-related negative effects.
In 2014, research into the toxicity of THC reported that 30mg of THC per kg of body weight is toxic and results in a 50% chance of death. An adult weighing 80kg would need to take 2.4g of THC to reach this level. To consume that amount of THC from CBD products would require you to swallow 2,400 bottles of full-spectrum CBD oil, each containing the maximum of 1mg THC.
What should I do if I take too much CBD?
If you experience side effects or symptoms after taking CBD such as drowsiness, stomach discomfort, nausea, and diarrhoea, don't take any more and contact your doctor immediately.
If you suspect that you or someone else is experiencing a CBD overdose, you must call 999 immediately. You should also call 999 if you or they experience:
loss of consciousness
a sudden state of confusion
fits that are not stopping
chest pain
breathing difficulties
If you think you may have taken too much CBD and you need urgent medical help, you can either contact your doctor or use the NHS 111 service.
How much CBD should I take?
Guidance from the Food Standards Agency recommends that "healthy adults do not take more than 70mg a day" when using CBD.
How CBD affects you depends on various factors, including body mass, body chemistry and general health. An amount that may suit one person may feel like too much for someone else. When starting with CBD, it's always best to start low and go slow. For example, start by taking 10mg twice per day. After a week, you can double that amount to 20mg twice per day.
Listen to your body and increase the amount you take accordingly, without exceeding 70mg per day. If in doubt, consult with a healthcare practitioner first.