What Is THC? Differences Between THC and CBD, Their Effects and Legal Status

When people hear "cannabis," most think of one thing; yet the plant’s two main compounds, THC and CBD, are quite different from each other. You may be wondering which one gets you high, which one has been studied for which conditions, or what it means when a product contains THC. In this article, we put the two compounds side by side and explain in plain language how they work, what research has found, their risks and their legal status in Turkey.

At a glance: THC and CBD

What are THC and CBD?

Both are found in the cannabis plant (Cannabis sativa) and belong to the cannabinoid family. Their chemical formula is the same: 21 carbon, 30 hydrogen and 2 oxygen atoms (PubChem: THC; PubChem: CBD). The difference lies in how the atoms are arranged: in THC one ring is closed, while in CBD it is open. This small difference completely changes their effects in the body.

What does THC stand for?

THC is short for tetrahydrocannabinol (in English, tetrahydrocannabinol). The compound mainly responsible for marijuana’s intoxicating effect is, by its full name, delta-9-tetrahydrocannabinol (Δ9-THC) (Grotenhermen 2003). THC made in the lab as a medicine is called dronabinol (Huestis 2007).

In the plant, both are first present in an "acid" form (THCA, CBDA); over time or with heat, they turn into THC and CBD. About 125 cannabinoids have been identified in cannabis so far (Radwan 2021). The amount of THC in the plant varies greatly by variety: in marijuana samples seized in the US, the THC content rose from about 4% in 1995 to about 12% in 2014; over the same period, the ratio of THC to CBD went from 14-fold to about 80-fold (ElSohly 2016). On plant types: the difference between hemp and marijuana.

How do they work differently in the body?

Our bodies have a system made up of their own cannabinoid-like compounds, the receptors these compounds bind to and the enzymes that make and break them down: the endocannabinoid system. The best known of these compounds made by the body are anandamide and 2-AG. The system’s most common receptor is CB1, which is plentiful in the brain; THC produces its effects by binding to these receptors (Lu and Mackie 2016).

• THC directly activates the CB1 and CB2 receptors (Pertwee 2008). THC’s intoxicating effect comes largely through these receptors in the brain.
• CBD does not activate these receptors the way THC does. In cell experiments, it was shown to bind to a different site on the CB1 receptor and dampen the receptor’s response (Laprairie 2015); in the lab, it also acts on many other targets (Pertwee 2008). It is still not known exactly which pathway is behind the effects of CBD we see in patients.

Does CBD soften the effects of THC?

This is a common idea, but research doesn’t support it. In a study of 46 volunteers, adding 1, 2 or 3 times as much CBD to the same amount of THC did not reduce THC’s impairment of memory or its temporary psychosis-like symptoms (Englund 2023). In an on-road driving study, a mix with equal amounts of THC and CBD impaired driving at least as much as THC alone, while a mix containing only CBD was no different from placebo (Arkell 2020). In other words, having CBD in a product does not make the THC in it safe.

What does the research say?

Both compounds are being studied intensively: as of October 19, 2026, 539 studies testing cannabidiol alone are registered on ClinicalTrials.gov (ClinicalTrials.gov). The results for pure CBD and for products containing THC differ, so we cover them separately. In the most reliable studies, patients are randomly assigned to groups: one group takes the product being tested, and the other takes an inactive look-alike (placebo).

Pure CBD

• Epilepsy: The approved CBD medicine reduced seizures when added to the medicines patients were already taking. In Dravet syndrome, the median number of seizures per month fell from 12.4 to 5.9, compared with 14.9 to 14.1 in the placebo group (Devinsky 2017); in Lennox–Gastaut syndrome, drop seizures fell by 43.9% with the medicine and by 21.8% with placebo (Thiele 2018).
• Pain and sleep: In 15 of 16 pain studies using pharmaceutical-grade CBD, there was no clear difference between people taking CBD and those taking placebo (Moore 2024). Products containing only CBD also showed no clear difference from placebo in sleep quality (da Silva 2025).
• Anxiety: In small studies using a public speaking test in people with social anxiety disorder, anxiety decreased; the US National Academies rate this as "limited evidence" (NASEM 2017). In longer and larger studies, results are mixed; research is ongoing. More detail: anxiety and CBD.

Products containing THC

• Chemotherapy nausea: In studies done between 1975 and 1991, THC-like medicines reduced nausea and vomiting more than placebo; but they were not compared with today’s anti-nausea medicines, and people stopped treatment because of side effects more often (Smith 2015). In patients whose nausea continued despite standard medicines, a THC:CBD capsule added to standard treatment raised the complete response rate from 8% to 24%; drowsiness and dizziness were more common (Grimison 2024).
• Muscle stiffness due to MS: A mouth spray containing both THC and CBD (nabiximols) increases the number of people reporting a meaningful reduction in muscle stiffness compared with placebo (moderate certainty) (Filippini 2022).
• Chronic pain: Medical cannabis products taken by mouth brought a small improvement in pain; side effects such as sleepiness and dizziness increased (Wang 2021).
• Sleep: In the analysis pooling studies, self-reported sleep quality was better with products that also contained THC than with placebo (da Silva 2025). But in a small study of 20 people diagnosed with insomnia, a single dose of a THC and CBD mix shortened total sleep measured in a sleep lab by about 25 minutes and dream sleep (REM) by about 34 minutes (Suraev 2026).
• Cancer, appetite and glaucoma: According to the US National Academies, there is not enough evidence that cannabinoids treat cancer or improve loss of appetite and weight loss in cancer; for eye pressure in glaucoma and for dementia symptoms, the limited evidence available suggests they are not effective (NASEM 2017).

The US National Academies’ 2017 report paints a similar picture for products containing THC: while it found strong evidence for chronic pain in adults, chemotherapy nausea and patient-reported muscle stiffness in MS, the report also stresses that there is no accepted standard for safe use or dosing of marijuana (NASEM 2017). These results belong to specific medicines of known content; they cannot be applied to unregulated products. Evidence topic by topic: CBD Guide.

Possible side effects and risks

THC

• In the short term: Impaired short-term memory and coordination and altered judgment; at high amounts, paranoia and psychotic symptoms can occur. It impairs the ability to drive (Volkow 2014).
• Dependence: Dependence develops in about 9% of people who try marijuana, about one in six of those who start in their teens and 25–50% of daily users (Volkow 2014). According to an analysis pooling many studies, about 22% of people who use marijuana have cannabis use disorder (Leung 2020).
• Mental health: There is strong evidence of a link between marijuana use and schizophrenia and other psychoses; the risk is highest in the most frequent users (NASEM 2017). In a European study, daily users of high-THC marijuana were about 5 times more likely to have psychosis than people who had never used it (Di Forti 2019).
• Young people: Frequent use in adolescence has been linked to changes in brain development, declining school performance and lower IQ scores (Volkow 2014). Starting at an early age is a known risk factor for problem use (NASEM 2017).
• Traffic and pregnancy: Marijuana use is linked to an increased risk of traffic accidents; smoking marijuana during pregnancy is linked to low birth weight (NASEM 2017).

CBD

• According to the World Health Organization, CBD is generally well tolerated and has shown no dependence potential in humans (WHO 2018).
• The most common side effects are drowsiness, diarrhea and decreased appetite (Epidiolex label).
• Liver: In healthy adults, with 5 mg of CBD per kilogram of body weight a day, liver values rose above 3 times normal within 4 weeks in 5.6% of participants (Florian 2025).
• Drug interactions: CBD can slow the breakdown of some medicines in the liver; interactions have been reported with epilepsy medicines such as clobazam and valproate, the blood thinner warfarin and transplant medicines such as tacrolimus (Epidiolex label). For the medicine you take: Check CBD drug interactions.

Pregnancy and breastfeeding: The US Food and Drug Administration (FDA) strongly advises against any use of CBD, THC and marijuana during this time (FDA 2019). More detail: CBD in pregnancy and breastfeeding.

Drug testing and sports

Urine tests look for traces of THC, not CBD. Even so, products sold as "CBD" can contain THC that isn’t listed on the label. In one study, an oil containing only 0.5 mg of THC turned a urine test positive with regular use; one sample also tested positive in one of 10 people taking pure CBD (Wolinsky 2026). The World Anti-Doping Agency (WADA) does not ban CBD, while THC is banned in competition (WADA 2027 list). More detail: drug testing, athletes and CBD.

What is THC-COOH?

In the liver, THC is first converted into 11-OH-THC, which is still active, and then into inactive THC-COOH (Huestis 2007). THC-COOH does not get you high, but because it stays in the body much longer than THC, urine tests look for it. So finding THC-COOH on a test does not point to a separate drug; it indicates that the person was exposed to THC. We explain how many days it shows up in urine, blood and hair in our drug testing guide.

Can a CBD product contain THC?

Yes. Products sold as "full-spectrum" contain small amounts of THC by definition; THC can also turn up in "broad-spectrum" products (CBD spectrum guide). THC was found in 21% of 84 CBD products bought online (Bonn-Miller 2017); in the US, 26% of 202 products did not match the type stated on their label (Gidal 2024). Even hemp seed oil is not exempt: THC was measured in all but one of 20 seed oil samples sold in Turkey (Kacargil 2026). In Turkey, support products and cosmetics that may be sold in pharmacies can contain no more than 0.3% THC; the product’s certificate of analysis shows this.

How has it been used in studies?

We don’t recommend personal doses on this site; the following only describes what was done in studies (study doses; not personal recommendations).

• In the epilepsy studies, the approved CBD medicine was given at 20 milligrams per kilogram of body weight a day, and patients were monitored under a doctor’s supervision (Devinsky 2017; Thiele 2018).
• In the chemotherapy nausea study, each capsule contained 2.5 mg of THC and 2.5 mg of CBD; the capsules were taken three times a day in addition to standard anti-nausea medicines, starting one day before chemotherapy and continuing until day five (Grimison 2024).
• Only about 6% of CBD taken by mouth on an empty stomach reaches the bloodstream (Perucca and Bialer 2020). When it was taken with a high-fat meal, the amount reaching the blood rose about 4-fold (Crockett 2020). There was no difference in blood levels between drops under the tongue and capsules (Johnson 2024).
• With products applied to the skin, the amount reaching the blood is small but not zero: in a study of 46 healthy adults, CBD passed from the skin into the blood with three of five products. No THC was detected in the blood and urine tests were not positive; even so, nine people went over the THC threshold on a saliva test (Zamarripa 2024).

Legal status in Turkey

In Turkey, marijuana containing THC counts as a narcotic substance. Under Law No. 2313, planting cannabis to obtain marijuana and growing cannabis without a permit are prohibited (Law No. 2313). The Turkish Penal Code treats buying, possessing or using narcotics for personal use as a separate offense punishable by two to five years in prison; for this offense, the filing of a public prosecution is deferred for five years, the person is placed on probation for at least one year, and treatment is provided if needed (TCK Art. 191).

Hemp-derived products, including CBD, on the other hand, may be sold only in pharmacies (Law No. 7557; January 31, 2026 regulation). Products in the medicine and health product classes are dispensed with a prescription; no prescription requirement is stated for support products with a THC content of no more than 0.3%. As of October 2026, there is no approved CBD medicine in Turkey; the list of licensed medicines published by TİTCK (Turkish Medicines and Medical Devices Agency) on October 16, 2026 contains no medicine with CBD (TİTCK). More detail: CBD laws in Turkey (not legal advice).

If you are considering CBD

You can talk with your doctor or pharmacist about the following:

• The complaint you’re considering it for, and what pure CBD and products containing THC have shown for it
• All the medicines and supplements you take; liver disease or regular alcohol use
• Any history of psychosis, bipolar disorder or a substance use problem (important when it comes to THC)
• Pregnancy, breastfeeding, driving and drug or doping tests
• Whether the product’s certificate of analysis states the amount of THC: how to read a label

If you are worried about marijuana use for yourself or someone close to you, the 115 counseling line of the Yeşilay Counseling Center (YEDAM) offers free psychological and social support to people with addiction and their families (YEDAM).

Conclusion

THC and CBD are two compounds that come from the same plant and share the same formula but behave very differently in the body. THC gets you high and carries well-known risks for dependence, mental health and driving; CBD does not get you high, but it calls for caution with drug interactions and the liver. Both have a place in research; the healthiest approach is to talk with your doctor about which one might be suitable, in which situation and for whom.

This article is for information only; it is not a diagnosis or treatment recommendation and does not encourage substance use. We don’t sell products or recommend any product or brand. How we prepare our content: Editorial Policy. If you spot an error, write to [email protected].

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