THC (tetrahydrocannabinol) is the primary psychoactive compound in cannabis. It binds CB1 receptors in the brain to produce the cannabis high, including euphoria, altered perception, time distortion, appetite stimulation, and pain relief. The full chemical name is delta-9-tetrahydrocannabinol; when sources say "THC" without qualification, they mean delta-9.

What does THC do to your body?

THC binds to cannabinoid receptors in the brain (CB1) and immune system (CB2). CB1 activation produces the recreational and cognitive effects (euphoria, time distortion, memory effects, slowed reaction time, appetite stimulation, pain reduction). It also raises heart rate acutely. Effects begin within minutes when smoked or vaped, 30-120 minutes when eaten, and last 2-12 hours depending on method.

How much THC is too much?

For most adults a single inhaled dose of 5-15 mg or an oral dose of 5-10 mg is moderate. Doses above 30-50 mg are high; above 100 mg are very high. Tolerance varies enormously — daily users can handle far more than infrequent users. New users should start with 2.5-5 mg of an edible or one small inhalation and wait for full onset before redosing. There is no documented fatal overdose threshold for adults, but uncomfortable acute reactions (anxiety, paranoia, vomiting, dissociation) become more likely at higher doses.

Yes, but at lower rates than alcohol, opioids, or nicotine. About 9% of adult cannabis users develop cannabis use disorder; the rate rises to about 17% for people who start in adolescence. Withdrawal is typically mild compared to other substances (irritability, sleep disturbance, decreased appetite, anxiety, restlessness) and resolves within 1-3 weeks of cessation.

What is the difference between THC and CBD?

They share the same molecular formula but differ in structure. THC binds CB1 receptors directly and produces a high. CBD does not bind CB1 strongly and does not produce intoxication. CBD also partially blocks THC at CB1, which is why CBD-containing products feel less intense than equivalent THC-only doses. See our CBD vs. THC comparison page for details.

What Is THC? The Cannabis Compound That Gets You High

Medical Disclaimer: This information is educational only and does not constitute medical advice. Cannabis affects everyone differently. Always consult a qualified healthcare provider before using cannabis, especially if you take other medications. Never discontinue prescribed medications without medical supervision.

The Short Answer

THC stands for tetrahydrocannabinol. It is the primary intoxicating compound in the cannabis plant. When you feel “high” from smoking weed, eating an edible, or vaping cannabis, THC is the molecule responsible. Its full chemical name is delta-9-tetrahydrocannabinol — the “delta-9” refers to the position of a specific double bond in the molecule. There are a few other naturally occurring variants (notably delta-8 and delta-10), but when cannabis pages, dispensaries, and researchers say “THC” without qualification, they almost always mean delta-9.

How THC Works in the Body

Your body has a built-in regulatory system called the endocannabinoid system (ECS). The ECS regulates mood, memory, pain perception, appetite, sleep, immune response, and motor coordination through cannabinoid receptors — primarily CB1 (concentrated in the brain and central nervous system) and CB2 (concentrated on immune cells).

THC binds directly to CB1 receptors, mimicking the body’s own endocannabinoids (anandamide and 2-AG) but with much greater intensity and persistence. This direct activation is what produces the cannabis high — the changes in perception, time distortion, euphoria, hunger, and the slowed cognitive processing.

THC also binds, more weakly, to CB2 receptors. CB2 is more relevant to THC’s anti-inflammatory and immune-modulating effects than to the intoxication.

What THC Feels Like

THC’s subjective effects depend heavily on dose, the user’s tolerance, the consumption method, and the surrounding terpene profile. Common effects at typical recreational doses (5–20 mg inhaled or 5–15 mg eaten):

Euphoria — a generalized feeling of happiness or well-being
Altered sensory perception — colors, sounds, and tastes feel more vivid
Time distortion — minutes can feel like much longer
Appetite stimulation — the “munchies”
Relaxation — reduced muscle tension, lowered inhibitions
Pain reduction — analgesic effects, particularly for neuropathic and inflammatory pain
Slowed cognitive processing — difficulty with short-term memory, attention, and complex reasoning
Reduced motor coordination — impaired reaction time and balance

At higher doses or in inexperienced users, THC can also produce anxiety, paranoia, increased heart rate, dry mouth, red eyes, dizziness, nausea, and in rare cases acute psychotic-like reactions. The relationship between THC dose and effect is biphasic — low doses tend to be calming and pleasant, while higher doses are more likely to produce uncomfortable effects. See our dosing fundamentals guide for more.

Onset and Duration by Method

THC’s pharmacokinetics depend almost entirely on how it gets into your body:

Method	Onset	Peak	Duration
Smoking flower	Seconds–minutes	10–30 min	2–4 hours
Vaporizing	Seconds–minutes	10–30 min	2–4 hours
Dabbing concentrates	Seconds	5–15 min	1–3 hours (very intense)
Edibles	30–120 min	2–4 hours	4–12 hours
Sublingual tincture	15–45 min	1–3 hours	4–8 hours

Edibles produce a substantially different experience because the liver converts ingested THC to 11-hydroxy-THC, a metabolite that is more potent and crosses the blood-brain barrier more readily than the parent compound. This is why eating cannabis tends to feel stronger, last longer, and feel more body-focused than smoking the same dose. See methods of consumption for the full comparison.

Therapeutic Uses of THC

THC is not just recreational. The 2017 National Academies of Sciences, Engineering, and Medicine (NASEM) report found conclusive or substantial evidence for cannabis (specifically THC and THC-containing products) for:

Chronic pain in adults
Chemotherapy-induced nausea and vomiting
Spasticity in multiple sclerosis

Beyond NASEM, THC has FDA-approved formulations: dronabinol (Marinol, synthetic THC) for chemotherapy nausea and AIDS-related anorexia, and nabilone (Cesamet, a synthetic THC analog) for the same indications. Nabiximols (Sativex, a 1:1 THC:CBD oromucosal spray) is approved in 29+ countries for MS spasticity but not in the United States.

How Long THC Stays in Your System

THC itself is rapidly cleared from the bloodstream — usually within hours of acute use. The detectable metabolite, THC-COOH, persists much longer because it’s fat-soluble and stored in adipose tissue. Detection windows vary widely by test type and use frequency:

Urine: 1–3 days for single use, 5–7 days for occasional use, 10–15 days for daily use, 30–90+ days for chronic heavy use
Blood: 1–7 days, longer for chronic users
Saliva: 24–72 hours
Hair: Up to 90 days

For a deep dive into the science and the “what actually works” question on clearance, see CannabisDrugTest.org. For our beginner guide: How Long Does THC Stay in Your System?

THC vs. CBD

THC and CBD share the same molecular formula (C₂₁H₃₀O₂) but a single structural difference — an open vs. closed ring — gives them radically different effects. THC binds CB1 directly and produces intoxication. CBD does not bind CB1 strongly and does not produce a high. CBD also partially blocks THC’s ability to bind CB1, which is why CBD-containing products tend to feel less intense than equivalent THC-only doses. See our full CBD vs. THC comparison.

Risks and Side Effects

Cannabis (and THC specifically) is comparatively low-risk among recreational substances — it has no documented fatal overdose threshold for adults — but it is not risk-free. Key concerns:

Acute anxiety and paranoia, especially at high doses or in inexperienced users
Cognitive impairment, particularly in adolescents whose brains are still developing
Cannabis use disorder — about 9% of adult users and ~17% of adolescent users develop dependence (see our CUD page)
Cardiovascular effects — THC raises heart rate acutely; recent research links chronic use to elevated cardiovascular risk (see cardiovascular risks)
Drug interactions — THC interacts with many medications via the CYP450 enzyme system (see drug interactions)
Pregnancy and breastfeeding — THC crosses the placenta and enters breast milk; avoid (see pregnancy & cannabis)
Driving impairment — do not drive after using THC; impairment can persist 4–8 hours after a single dose (see driving & impairment)

Full overview: Cannabis Side Effects.

Legal Status

Delta-9 THC remains a Schedule I controlled substance under U.S. federal law as of May 2026, though the DEA initiated a rescheduling process in 2024 that is still in progress. At the state level, THC is legal for adult recreational use in 24+ states and for medical use in most others. State-by-state rules vary widely on possession limits, public consumption, driving thresholds, and home cultivation.

Hemp-derived delta-9 THC products containing under 0.3% THC by dry weight are technically legal under the 2018 Farm Bill, but state-level regulation of hemp-derived THC is in active flux. See our state laws guide and Am I Legal? tool.

The Bottom Line

THC is the cannabinoid that defines the cannabis experience. It produces both the recreational high and most of the medical benefits people seek from cannabis — pain relief, appetite stimulation, anti-nausea effects, and muscle relaxation. It also produces the side effects, the addiction potential, the cardiovascular risk, and the cognitive impairment.

Understanding THC means understanding cannabis. If you’re new to weed, start with a low dose (under 5 mg if eating, a single small inhalation if smoking), give it time to take effect before redosing, and be patient with the learning curve. See our dosing fundamentals for the full beginner protocol.