What Is THC?
THC stands for delta-9-tetrahydrocannabinol or Δ-9-tetrahydrocannabinol (Δ-9-THC). It is a cannabinoid molecule in marijuana (cannabis) that’s long been recognized as the main psychoactive ingredient—that is, the substance that causes people who use marijuana to feel high.
THC is just one of more than 500 different substances—and 100 different cannabinoid molecules—in marijuana.1 Although THC is the most recognized, another important cannabinoid molecule that has received major interest is cannabidiol (CBD).
History of THC
Cannabis has a long history of use that dates back thousands of years. The first recorded use of cannabis has been traced to China, where it was used for food, textiles, and medicine. Hemp was eventually introduced to Europe and later to the Americas, where it was used for both recreational and ritual purposes.2
Cannabis was introduced to what is now the United States during the 1600s. Hemp was grown to produce textiles and sometimes even used as legal tender. It was used for a number of medical purposes as well, with its recreational use beginning to grow during the 1930s and 1940s.
Around this time, anti-drug campaigns were instituted against its use and many states passed laws prohibiting marijuana. The 1936 film “Reefer Madness” portrayed marijuana as a dangerous drug that led to psychosis, violence, and suicide.
In 1970, the Controlled Substances Act classified marijuana as a Schedule I drug, identifying it as having a high potential for abuse and making the drug illegal at the federal level. The “war on drugs” launched during the 1970s led to the large-scale incarceration of many people for marijuana possession and use.
Statistics suggest that the enforcement and penalization of marijuana laws disproportionately target people of color. While drug use has similar rates for people of all racial and ethnic backgrounds, Black and Latinx people are far more likely to be arrested and jailed for drug offenses.3
While it is still not legal at the federal level, many states have approved the use of cannabis and THC for medical and, in some states, recreational purposes. Always check state laws before purchasing any products containing THC.
How THC Works
THC works by attaching to the body’s cannabinoid receptors, which are found throughout the brain and nervous system. THC can be detected in the body much longer than most other drug compounds, although the psychoactive effects only last a few hours.
THC is stored in body fat and organs for three to four weeks. Hair follicle testing may identify THC after even longer periods of time, around 90 days. Urine testing is often used but has been found to be an unreliable method of detection.
Forms of THC
THC is often smoked as marijuana (dried leaves of the Cannabis plant), but there are actually a number of different ways it can be used. THC can be consumed by:
Inhalation: This is the fastest method of delivery and produces the quickest psychoactive effects, often within minutes. THC can be inhaled via smoking, vaping, or dabbing. Recent reports suggest that vaping THC oil may pose safety risks that warrant further investigation.5
Oral ingestion: THC can be taken by mouth in the form of capsules, edibles, tinctures, or oils. While this method of delivery takes longer to have an effect, the drug’s effects tend to last longer.
Topical application: THC can also be included in lotions, balms, salves, oils, and bath salts that are then applied to the skin. The effects of this method are usually localized, which means that they are unlikely to have psychoactive effects. However, such products may be helpful for reducing pain and inflammation.6
Sublingual administration: THC can also be consumed as lozenges, sprays, or dissolvable strips that are placed under the tongue and dissolved.
THC in CBD Products
With the popularity of CBD, there has been a major market shift toward producing a seemingly endless variety of CBD products. Some of these products may contain traces of THC (around 0.3% to 0.9%), depending on how they’re formulated.7
This small concentration is highly unlikely to result in a high feeling, and some experts argue that the effectiveness of CBD is potentiated by small amounts of THC.8
However, if you’re looking for a CBD product without any THC, be sure to select one that uses third-party testing to certify the purity of the product.
Uses of THC
THC is used recreationally, but it has a number of medicinal uses as well. Marijuana has been used for medicinal purposes for thousands of years, although scientific research on its use to alleviate and treat illness is still relatively recent.
Some of the ailments that THC may help include:9
Inflammatory bowel disease (IBD)
Irritable bowel syndrome (IBS)
Opioid use disorder
Post-traumatic stress disorder (PTSD)
Symptoms associated with HIV/AIDS
The FDA has also approved the synthetic THC medication dronabinol (sold under the brand names Marinol and Syndros) and a drug containing a synthetic substance similar to TCH known as nabilone (brand name Cesamet). Dronabinol is used to treat vomiting and nausea caused by chemotherapy and low appetite and weight loss caused by HIV/AIDS. Nabilone is also used to treat nausea and vomiting.9
Impact of THC
THC stimulates the release of a neurotransmitter called dopamine in the brain, which is what causes feelings of euphoria. Although, the effects on the body can vary from one person to the next.
People using THC may experience:10
Altered perception of time
Feelings of relaxation
Heightened sensory perception
While it can cause pleasant effects, TCH can also lead to adverse reactions as well. Some of the most common include coughing fits, anxiety, and paranoia, along with chest or lung discomfort, and “body humming.” Some people also experience fainting, hallucinations, or cold sweats due to THC use.11
Potential Pitfalls of THC
There is considerable research-based evidence that THC is associated with an increased risk of psychosis, both among adolescents and adults.12 It is also linked to increased anxiety, learning impairment, and decreased memory formation.
CBD has been found to help counter these effects, reducing anxiety, improving learning ability, and working as an antipsychotic—although much of the available research is on animals.13 When taken together, as is the case with marijuana use, CBD seems to reduce the negative effects of THC.
A 2013 meta-analysis, which is a type of study that looks at the results of many previous studies, also found some evidence that THC may be neurotoxic as there are differences in the brain structure of people who regularly use marijuana (and who do not have psychosis).14
One interesting point underscoring brain changes: While research has shown a reduction in gray matter volume in the prefrontal cortex of people with a history of heavy marijuana use, there is an apparent compensatory response. The density of fibrous connections among remaining neurons increases, which may cancel out some or all of the neurotoxicity.