The Difference Between CBD and THC
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A pharmacist explains the nuances of these two cannabis plant compounds
Medically reviewed by Femi Aremu, PharmD
CBD (cannabidiol) and THC (tetrahydrocannabinol) are the two major compounds found in the cannabis plant.
Each has unique properties, potential health benefits, and side effects.
The following article covers CBD and THC, their effects, their legal status, and their safety considerations.
miodrag ignjatovic / Getty Images
Male added CBD oil into his morning tea to use it as a medicine.The Difference Between CBD and THC
CBD and THC are known as cannabinoids. They have very similar chemical structures and activate the same receptors within the body's endocannabinoid system.
This system is involved in essential processes in the body, including the following:
Brain development
Immune system regulation
Pain perception
Motor control
Despite their similarity in structure, CBD and THC exert entirely different effects.
Psychoactive vs. Nonpsychoactive
The most significant difference between these two compounds is that THC is psychoactive. This means it can affect how the brain works.
THC activates the body's "reward" pathways to produce the "high" that's associated with marijuana use. It does this by activating, or turning on, a cannabinoid receptor called CB1. When THC activates this type of receptor, things like movement, body temperature, and brain function are affected.
In contrast, CBD is not considered psychoactive. It does not cause euphoria or a "high," even at large doses.
The Research
Cannabis products have been studied for the following medical conditions:
Much of the research on CBD and THC is preclinical, meaning it's been studied in animal models.
Large-scale human trials are necessary to determine if CBD or THC can help treat most of these conditions.
What Is CBD?
CBD is commonly available in the following forms:
Though it does act on cannabinoid receptors, CBD mainly affects other receptors, including serotonin receptors.
It may help counteract some of the negative effects of THC, including serious side effects like psychosis.
CBD has many purported therapeutic properties. Research is limited, but some studies show it may benefit those who have the following conditions:
Pain. Overall, there isn't enough evidence that CBD by itself helps with pain. Some research has shown that high doses can improve neuropathy (nerve pain), though more data is necessary.
Anxiety. So far, the results are mixed. Some studies show that CBD can improve symptoms of social anxiety disorder and post-traumatic stress disorder (PTSD), while others show no effect.
Seizures. Epidiolex, a purified CBD oil, is approved by the U.S. Food and Drug Administration (FDA) for some hard-to-treat types of childhood epilepsy.
Brain protection. Animal studies have shown that CBD may have benefits for those who have Alzheimer's disease or Parkinson's disease, but human clinical trials are necessary to verify these effects. Effects on animals may or may not translate into benefits for humans.
What Is THC?
THC is the psychoactive ingredient from the marijuana plant. The possession and use of marijuana and THC-containing products are not legal in all U.S. states.
Apart from a few prescription products, THC is available in the following forms:
Cigarettes
E-cigarettes (by vaping)
Drinks
THC is effective for increasing appetite and for nausea and vomiting related to cancer chemotherapy.
The FDA has approved the following THC-based prescription medications:
Cesamet (nabilone), chemically similar to THC, taken for cancer-related nausea and vomiting
Marinol (dronabinol), synthetic THC (made in a lab), taken for cancer-related nausea and vomiting or weight loss in people with AIDS
Syndros (dronabinol), a liquid for cancer-related nausea and vomiting or weight loss in people with AIDS
Other conditions that THC may be effective for include:
Pain. Prescription THC products have been shown to improve neuropathy and quality of life.
Spasticity (muscle tightness). Sativex (nabiximols), a mouth spray that combines THC and CBD, is approved for spasticity in Europe.
PTSD. A very small trial found that Cesamet reduced nightmares in 10 military personnel with PTSD.
Irritable bowel syndrome (IBS). Smoking THC was found to improve symptoms of IBS, but benefits may be only short-lived. People who used THC long-term were more likely to ultimately require surgery for IBS.
Notably, most of the research into THC's effects has used standardized THC prescription medications. Other THC-containing products available at dispensaries may or may not be beneficial for any of these conditions. More research is undoubtedly necessary.
Legality and Regulation
Understanding how CBD and THC are regulated in the United States is a bit tricky. Basically, it comes down to the source of the product, whether it comes from the marijuana plant or hemp plant.
In 2018, the U.S. legalized CBD that contains less than 0.3% THC. Plants that contain this low concentration of THC are known as hemp. Historically, hemp has been used to make things like fiber and paper.
Notably, marijuana (which comes from a cannabis plant with more than 0.3% THC) remains a Schedule 1 controlled substance. This means that the FDA considers it to have a high risk of abuse and no accepted medical use. Accordingly, CBD and THC that come from a marijuana plant are also Schedule 1 controlled substances. These are illegal in the U.S.
Using cannabis derived from hemp for medical purposes is legal in 47 U.S. states as of 2024. This typically refers to either CBD or THC at low concentrations (less than 0.3%). Some states allow recreational cannabis use as well.
There are many gray areas, though. If you travel between states, check the latest guidelines for the state you'll visit. Some states don't allow products purchased in other states or only allow cannabis for specific medical conditions, for example.
To further complicate the picture, research shows that labels of cannabis products aren't always accurate. Levels of THC listed on a product label may be either higher or lower than what's actually in the product. Overall, there's been a marked shift to increasingly higher concentrations of THC in cannabis plants, which makes side effects and toxicity more likely.
Side Effects and Risks
CBD can cause the following side effects, typically involving the gastrointestinal tract:
Vomiting
Fatigue or drowsiness
We don't know much about the long-term effects of CBD; more research is necessary.
CBD is also associated with a host of drug interactions, mostly involving medicines that are broken down by the liver. A few of CBD's effects on prescription medications or recreational drugs include:
Increasing the levels of seizure medicines like Onfi (clobazam) in the body
Increasing the sedating effects of alcohol
Increasing levels of antidepressants, which can also increase the side effects of these medicines
Increasing risk of liver toxicity when combined with Tylenol (acetaminophen)
This list is not all-inclusive. Be sure to discuss your medication list with your healthcare provider or pharmacist before taking a CBD product for optimal safety.
The side effects of THC can be very serious. These often involve the brain and include:
Cognitive impairment, including problems paying attention, learning, and remembering things. The risk of impaired mental function is highest among young users of THC and those who use high concentrations of it.
Motor impairment. Drivers under the influence of THC are twice as likely to be involved in vehicle crashes.
Risk of addiction. Although public opinion suggests THC is safe, research shows that up to one in three people who use THC become dependent on it.
Anxiety and fear, especially if large doses are taken.
Psychosis, including hallucinations (seeing things that aren't there) and paranoia
Respiratory depression (shallow breathing), changes in the brain, or coma in children.
In addition, the long-term use of THC and THC-containing products, particularly by inhalation (smoking or vaping), is associated with lung and heart disease.
THC has very negative impacts on the brains of children and adolescents. It's particularly dangerous for these groups. THC can actually rewire the reward and stress signals in the developing brain, which increases the chances of both drug addiction and psychosis later in life.
Take a look at these startling statistics:
Adolescents who use THC are four times as likely to become dependent on THC than people who start using it in adulthood.
Using THC before age 17 predisposes people to mental health conditions like depression, anxiety, and schizophrenia. Research shows that avoiding high levels of THC could prevent psychotic disease in almost one in four people.
It's unclear whether THC functions as a "gateway drug" by rewiring the brain's addiction and reward functions. It is possible that using THC could make it easier for someone to get hooked on a "harder" drug.
Summary
CBD and THC are the two main components of the cannabis plant.
They are similar in structure but have very different effects. THC is responsible for the "high" associated with marijuana use, while CBD is not mind-altering.
Though marijuana is still illegal in the U.S., CBD products that come from the hemp plant and contain less than 0.3% THC are legal in most states. Keep in mind, though, that this does not mean that CBD and THC are safe.
CBD may cause gastrointestinal side effects. There's very little data on its long-term use.
THC can cause serious effects on the central nervous system. These include anxiety, cognitive impairment, and psychosis. THC is especially risky for children and teens because they are more likely to become dependent on it or develop mental health conditions.
Read the original article on Verywell Health.
