Cannabidiol (CBD) is a substance present in the cannabis plant that people can use for many reasons. Evidence notes that individuals can tolerate relatively high doses of CBD, and there is little evidence of people overdosing.

CBD is one of more than 500 compounds present in the cannabis plant. When a person uses CBD, it interacts with the endocannabinoid system. This refers to a complex biological system with receptors all over the human body. These receptors make up part of the body’s nervous system and play a role in many processes, including appetite, pain, and memory.

A 2018 study showed that people take CBD for several reasons, such as treating:

While more research is necessary, evidence suggests that people can tolerate CBD well, particularly when using appropriate doses, such as the recommended dosage on many CBD products.

In this article, we discuss the advisable maximum dose of CBD, what happens if a person takes too much, and what to do in an emergency.

Is CBD legal?The 2018 Farm Bill removed hemp from the legal definition of marijuana in the Controlled Substances Act. This made some hemp-derived CBD products with less than 0.3 percent THC federally legal. However, CBD products containing more than 0.3 percent THC still fall under the legal definition of marijuana, making them federally illegal but legal under some state laws. Be sure to check state laws, especially when traveling. Also, keep in mind that the FDA has not approved nonprescription CBD products, and some products may be inaccurately labeled.

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Currently, the Food and Drug Administration (FDA) does not regulate all products that contain CBD. As such, it can be difficult to discern safe and suitable dosages for using CBD.

However, the World Health Organization notes that CBD is safe when a person uses it appropriately. Additionally, while more research is necessary, a 2017 research review showed that humans can tolerate CBD doses of up to 1,500 milligrams (mg) per day.

At present, the FDA has only approved one cannabis-derived product for use in the United States. This is a prescription drug known as Epidiolex, which contains CBD. Epidolex can treat seizures in people with Lennox-Gastaut syndrome, Dravet syndrome, and tuberous sclerosis complex.

When using Epidolex, health experts recommend a starting dosage of 2.5 mg per kilogram of body weight (mg/kg) twice a day. This is a total dosage of 5 mg/kg each day. For example, using this dosage, a person weighing 70 kg would take a total dose of 350 mg per day.

After 1 week, a person can double the dosage to 5 mg/kg twice a day, for a total of 10 mg/kg each day. Using the same example, a person weighing 70 kg would now take a 700-mg dose each day.

In a 2020 review, researchers looked at data from 362 studies involving the use of CBD. The studies about CBD use for anxiety involved doses of up to 900 mg. Studies about CBD use for psychosis involved doses of up to 1,000 mg.

The review noted that most studies reported no side effects with acute CBD administration and mild to moderate adverse effects with chronic administration.

A 2019 review showed that factors that can contribute to potentially adverse effects of CBD may include:

  • CBD potency
  • route of administration, such as inhalation, oral, or sublingual
  • concurrent drug use
  • drug interactions

If a person decides to use CBD products, they may want to consider purchasing these products from a reputable source and discussing taking CBD with their healthcare professional. A doctor can provide advice on suitable dosages and ensure that CBD will not impact other medications a person currently takes or cause any adverse effects.

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People can tolerate CBD in high doses and it is unlikely to cause people to experience intoxication. However, some people may have negative side effects from using CBD. These can include:

  • drowsiness and other changes of alertness
  • diarrhea
  • decreased appetite
  • irritability
  • agitation

The FDA also states CBD has the potential to cause a person harm. It suggests CBD may:

  • cause liver injury
  • affect how other drugs a person takes work, potentially causing serious side effects
  • slow brain activity if a person takes it with alcohol or other drugs, increasing the risk of sedation or drowsiness

Animal studies also suggest that CBD can cause infertility in males. However, more research is necessary to determine if this will affect humans.

There is little research into what can happen if a person takes too much CBD. In a 2020 case study, a 56-year-old male ingested two packets of CBD gummies. This was a total dose of 370 mg of CBD. The male arrived at the emergency department via ambulance after his colleagues noticed him:

  • behaving bizarrely
  • slurring his speech
  • vomiting

The individual had no known history of substance misuse and no prior medical conditions. He had legally purchased the CBD gummies to treat his back pain. The medical team assessed the male and administered him:

  • intravenous fluids
  • oxygen
  • antiemetics for vomiting
  • consistent stimulation

The following day, the male made a full recovery. The case study’s authors stated that it was difficult to know whether this was a true CBD intoxication. They added that contamination of the product with unknown toxins may have caused the reaction.

If a person takes CBD, they may experience some side effects. This can be due to the CBD alone, contamination of the product, or potential interactions with other drugs a person may be taking. The most common side effects of CBD are not serious and will go away without treatment.

However, if a person takes CBD and experiences the following symptoms, it is advisable that they receive medical help:

  • psychosis
  • hallucinations
  • delusions
  • loss of consciousness

These are not side effects of CBD. However, they may indicate that a person has taken a contaminated product. As the FDA has only approved one CBD product for medical use, many unregulated products are on the market. This means contamination is a potential risk of using currently available CBD products.

Other side effects may be due to the concurrent use of CBD alongside alcohol or other drugs, which can increase the risk of sedation and drowsiness. This can lead to injuries.

Evidence notes that CBD is generally safe, particularly when people use an appropriate dosage. However, some people may still experience side effects from using these products. While more research is necessary to understand tolerance and dosage guidelines, some evidence indicates that people can safely tolerate doses of up to 1,500 mg per day.

There is very little evidence of people overdosing on CBD. However, it is important that people use CBD products appropriately. This includes following dosage guidelines on products, purchasing from reputable sellers to avoid contaminated products, and consulting with a doctor to ensure suitable dosages and that CBD will not interact with any current medications.