THC – Tetrahydrocannabinol

Tetrahydrocannabinol (THC) is a psychoactive substance that belongs to cannabinoids. It is the best-known and most abundant cannabinoid in cannabis (hashish, marijuana) and, at the same time, its main active ingredient. 

The American Roger Adams identified cannabidiol (CBD) from the hemp plant and thus determined the connection to THC. In 1964, THC was first isolated in pure form by the two scientists Yehiel Gaoni and Raphael Mechoulam in Israel.

Pharmacology: How THC works

The so-called endocannabinoid system fulfills essential protective functions in the human body. For example, it counteracts stress or helps regulate various processes: endogenous messenger substances. This system includes different cannabinoid receptors; of these, two main types exist the CB1 and CB2 receptors. The CB1 is mainly located in the central and peripheral nervous system and controls, among other things, feelings of happiness, relaxation, and pain perception. CB2 receptors perform an essential function in the immune system.

Substances from the hemp plant, such as THC and CBD, dock onto these receptors, interact with them, and consequently affect them.

THC content in cannabis

The THC content varies greatly depending on the plant variety. The unfertilized inflorescences contain the most THC. The rest of the plant has only a tiny proportion, while the plant seeds contain no THC.

THC content in marijuana

When it comes to marijuana, one assumes an active ingredient range of 2 to 20%, with certain cannabis varieties exceeding 25% (under the best conditions). In the case of medical cannabis in Germany, the THC values range between less than one and up to 22%.

THC content in hash

Hashish is pressed resin from the hemp plant that is smoked or dissolved in fat and used in drinks and food. Assuming an average extract content of 20%. Individual varieties have an active ingredient content of over 30%.

THC content in hash oil

The oil extracted from the hemp plant with solvents is vaporized, smoked, pure, or mixed with tobacco, dripped onto paper and sucked, or used to prepare drinks and food. Hemp oil reaches a THC content of up to 80%.


One can consume THC can in a variety of ways. Smoking hashish or marijuana neat or mixed with tobacco is considered the most common form of THC consumption. In addition to joints, unique smoking accessories such as pipes, water pipes, or bongs are also used. However, You can also vaporize and inhale THC using a vaporizer.

Consumption often takes place through food intake. Food, such as muffins, cakes, etc., and drinks containing THC often have a more substantial effect than a comparable smoking dose. When THC is ingested through food, the THC is absorbed in the stomach and upper intestines; then, it goes to the liver, and from there, it is finally transported to the brain. A delay of up to four hours must be assumed here.


When consuming cannabis, parts of the brain are stimulated, which causes the release of the hormone dopamine, which in turn can lead to a wide variety of conditions. The broad spectrum of psychological effects is very characteristic of the impact of THC in cannabis. The partial unpredictability of the effect is not irrelevant and depends on a variety of factors. These include the following:

  • Form of consumption (smoking, eating)
  • The technique of consumption (depth of inhalation)
  • Consumption amount
  • THC content
  • Use experience (first-time or frequent use)
  • Situation of consumption
  • Mental state

The possible effects of intoxication can be divided into immediate psychological and physical consequences.

Psychic Effects

  • Current emotional state is amplified (both sad and happy)
  • Impairment of the ability to react and concentrate
  • Impairment of logical thinking
  • Increase of the urge to talk and laugh
  • Relaxation
  • Perception is changed (experience of time, intensity of colors)

Physical Effects

  • Increase in pulse rate and blood pressure
  • Cravings, dry mouth
  • Dilated pupils

One doesn’t fully understand the mechanisms of action of THC.

On average, the effects last about two hours and appear a few minutes to a few hours after ingestion (depending on the intake form). Psychomotor impairments may persist after any perceived high has passed.[1]


Whether and to what extent THC is dangerous to health one cannot answer it in general, or many factors influence it. Among other things, the risks listed below depend heavily on the social environment in which the consumer is, how old he is, his condition, and, last but not least, the quantity, frequency, and reasons for consumption.

Risk of accidents
Because the reaction of your ability is impaired, an increased risk of accidents must be expected under the influence of cannabis.

Quite unpredictable effects can occur if you consume cannabis with alcohol, medication, or other drugs.

Mental disorders
If someone has a predisposition to mental disorders (e.g., schizophrenia), the consumption of THC can promote the onset of this.

Damage to health
If cannabis is smoked, there is an increased risk of cancer and damage to the lungs and airways.

Criminal consequences
In many countries, THC is an illegal substance; Consequences under criminal law are, therefore, one must expect when consuming it.

Although it is almost impossible to die from a THC overdose (not a single death has been recorded), excessive cannabis use can have unpleasant effects.

Effects of overdose

  • Nausea and vomiting
  • Panic, fear, paranoia
  • Impaired concentration
  • Impairment of motor skills
  • and more

Long term consequences

Research has often produced conflicting results regarding the psychological, social, and physical risks of long-term and frequent cannabis use. A variety of possible long-term consequences have been studied. The following are known so far:

Physical consequences

  • Impairment of lung function
  • Impaired cognitive performance (including concentration, attention, and memory)

Severe brain damage, as is well known with alcohol, is not caused by cannabis consumption. In any case, the effects of consumption during pregnancy and on the newborn are controversial. There is a lack of clear evidence from research on the influence cannabis has on the hormone and immune systems.

Psychological and social consequences

Research suggests that cannabis, especially at high THC doses, can trigger psychotic symptoms. These usually disappear after a few days. However, an independent “cannabis psychosis” could not be proven. Instead, one proceeds from the assumption that a hitherto hidden psychotic illness is likelier to break out in susceptible cannabis users than in abstainers.

Furthermore, general withdrawal tendencies can go hand in hand with consumption. In the context that those affected are indifferent to everyday tasks, one speaks of the “amotivational syndrome.” Today, however, this one-dimensional cause-effect relationship assumption is no longer tenable. Rather, the person’s characteristics can be identified to explain the state of mind.[2][3][4]

Cannabis addiction

Cannabis addiction manifests itself as an unsuccessful attempt to reduce or eliminate use. Regular consumption can lead to psychological and mild physical dependence. While the physical dependency is not as intense as with alcohol or opiates, for example, the psychological dependency can be quite pronounced. There are no external signs of dependence.

It depends very much on the extent to which the psychosocial risk factors are present. So someone can be more or less at risk of developing a (cannabis) addiction. This means that in many cases, the primary problem is not due to the effect of the substance but instead to psychological issues. The early entry into the consumption of cannabis, cigarettes, and alcohol is considered a non-irrelevant risk factor for developing an addiction.[5]

Under the so-called “gateway drug” term, cannabis has long been a subject of controversy. Cannabis has been blamed for the fact that almost all heroin addicts were early cannabis users. Conversely, however, this does not apply to cannabis users: only a minimal proportion of them switch to other drugs.


They tested the possible toxicity of THC on mice and rhesus monkeys. Studies have concluded that in mice, the lethal dose of pure THC when administered intravenously is 42 mg per kilogram of body weight; when taken orally, however, it is 482 mg per kilogram of body weight; in rhesus monkeys, death occurs due to respiratory failure and heart failure after intravenous administration of 128 mg/kg body weight.[6]

According to projections, a person weighing 70 kg would die after oral consumption of 10.5 g of THC, with a probability of 50%. This amount can be found in around 70 to 130g of cannabis with a THC content of 8 to 15%. Other researchers assume a lethal, i.e., deadly dose of just over 4 grams.[7]Because the lungs can only absorb about 20% and the intestines about 6% of the active ingredient THC,[8]it is believed that it is virtually impossible to ingest lethal amounts of THC when ingesting natural cannabis. These levels are not achievable by smoking, eating, or drinking cannabis.

The extrapolated amount required for a fatal effect of THC in humans is about 1000 times higher than the usual consumption level. To date, no human case has been recorded in which an overdose of cannabis had a fatal outcome.[9]

Dismantling of THC

THC is broken down within a few hours via the intestines, kidneys, and liver. Because THC is difficult to dissolve in water but is easily soluble in fat, the residues are stored in the body’s fatty tissue and can therefore be detected for longer.

Detection times

The detection time of THC is significant in the context of traffic controls or company medical examinations. For such or similar checks, the following two values, in particular, are taken into account:

  • Active THC Level (Delta-9 THC)
  • THC metabolites (THC-COOH)

The active value provides information about how long it has been since the last consumption of THC. The second value, the passive value, can be used to determine the frequency of consumption. The degradation products are created by the human organism’s metabolization (metabolism) of THC. Since it is a lipophilic, i.e., a fat-soluble substance, the degradation products are deposited in body fat.

The physical constitution and the individual metabolism play an essential role in the detection time. It is, therefore, not possible to make general statements. However, the active THC value is detectable for at least 7 hours to a few days, depending on the form of consumption, strength, and frequency. In the case of degradation products, it is at least three days or a few weeks, sometimes up to several months.

With the tests provided for this purpose, 0.5 nanograms per milliliter (ng/ml) of THC and 0.5 nanograms per milliliter of the metabolite (THC-COOH) can be detected in the blood. The breakdown of the two values, THC (active value) and THC-COOH (breakdown products) are not linear, so large differences between people must be assumed. It is, therefore, also possible that positive evidence can still be found after significantly longer periods of abstinence.[10][11]

In the overview below, you can find the average detection times in the blood and urine of the active value and the breakdown products. As already mentioned, there are differences between first-time and regular use.

Note: This information is supplied without liability.

THC consumption
for the first time
THC consumption
THC-COOH consumption
for the first time
THC-COOH consumption
Blood test7 – 12 hoursup to 27 hours3 – 7 dayssome weeks
Urine test3 – 5 days4 – 6 weeks

Medical application

One also found THC in a wide variety of medicines. Germany, for example, tests THC’s effectiveness for treating glaucoma and autoimmune diseases (e.g., multiple sclerosis and Crohn’s disease). In America, THC drugs are approved for treating anorexia (anorexia) and cachexia (weight loss) in AIDS.

A study at the Hannover Medical School concluded that tics in Tourette syndrome sufferers are effectively reduced by treatment with THC.[12]

To treat pain caused by damage or disease of the nervous system, spasms in multiple sclerosis, and relieve pain, nausea, and vomiting in cancer and AIDS, a medicinal product containing the herbal active ingredients THC and CBD has been developed in Austria, UK and Canada approved. Additional treatment areas of THC are still in the clinical testing phase.[13][14]

According to a study, other effects with therapeutic potential are attributed to this active ingredient, regardless of the approval of THC as a drug; these include:

  • It has an appetizing effect
  • Relief of inflammation-related pain
  • Relief of spasticity
  • Relief of Nausea and vomiting
  • Reduction of intraocular pressure
  • Sleep is facilitated
  • Production of the appetizing effect
  • The spread of cancer cells is inhibited[15]



[1] Roger G. Pertwee: Pharmacological and therapeutic targets for Δ9-tetrahydrocannabinol and cannabidiol. In: Euphytica. Band 140, Nr. 1–2, 2004, S. 73–82

[2] J. A. McLaren, E. Silins, D. Hutchinson, R. P. Mattick, W. Hall: Assessing evidence for a causal link between cannabis and psychosis: a review of cohort studies. In: The International journal on drug policy. Band 21, Nummer 1, Januar 2010, S. 10–19, doi:10.1016/j.drugpo.2009.09.001. PMID 19783132 (Review).

[3] S. Minozzi, M. Davoli, A. M. Bargagli, L. Amato, S. Vecchi, C. A. Perucci: An overview of systematic reviews on cannabis and psychosis: discussing apparently conflicting results. In: Drug and alcohol review. Band 29, Nummer 3, Mai 2010, S. 304–317, doi:10.1111/j.1465-3362.2009.00132.x. PMID 20565524.

[4] T. H. Moore, S. Zammit, A. Lingford-Hughes, T. R. Barnes, P. B. Jones, M. Burke, G. Lewis: Cannabis use and risk of psychotic or affective mental health outcomes: a systematic review. In: Lancet. Band 370, Nummer 9584, Juli 2007, S. 319–328, doi:10.1016/S0140-6736(07)61162-3.

[5] U. Bonnet, N. Scherbaum: Evidenzbasierte Behandlung der Cannabisabhängigkeit, Deutsches Ärzteblatt, Dezember 2005

[6] Eberhard Teuscher, Ulrike Lindequist: Biogene Gifte. Akademie-Verlag, Berlin 1988, Letale Dosen von THC bei Maus und Rhesusaffe, S. 65 f.

[7] Lester Grinspoon, James B. Bakalar: Marihuana, die verbotene Medizin. Zweitausendeins, Frankfurt am Main 1994, ISBN 3-86150-060-4.

[8] Gabriel G. Nahas: Toxicology and pharmacology of cannabis sativa with special reference to Δ 9-THC. In: Bulletin on Narcotics. Band 24, Nr. 2, 1972, S. 11–27.

[9] J. Michael Walker, Susan M. Huang: Cannabinoid analgesia. In: Pharmacology & Therapeutics. Band 95, Nr. 2, 2002, S. 127–135, doi:10.1016/S0163-7258(02)00252-8: “…to date, there are no deaths known to have resulted from overdose of cannabis. (S. 128) ”

[10] Grotenhermen F. Pharmacokinetics and pharmacodynamics of cannabinoids. Clin Pharmacokin 2002, in press

[11] Coleman DE Baselt RC. Efficacy of two commercial products for altering urine drug test results. J Toxicol Clin Toxicol (1997) 35(6):637-642

[12] K. R. Müller-Vahl u. a.: Delta 9-tetrahydrocannabinol (THC) is effective in the treatment of tics in Tourette syndrome: a 6-week randomized trial. In: J Clin Psychiatry. 2003. PMID 12716250.

[13] Fünfundzwanzigste Verordnung zur Änderung betäubungsmittelrechtlicher Vorschriften (BGBl. 2011 I S. 821)

[14] Sativex® approved in Germany for the treatment of spasticity due to Multiple Sclerosis. (Memento vom 6. März 2016 im Internet Archive) GW-Pharmaceuticals, 26. Mai 2011, abgerufen am 10. Dezember 2017.

[15] Roger G. Pertwee: Pharmacological and therapeutic targets for Δ9-tetrahydrocannabinol and cannabidiol. In: Euphytica. Band 140, Nr. 1–2, 2004, S. 73–82, doi:10.1007/s10681-004-4756-9