Illegal drugs and drug addiction

Drugs can affect their users differently, for example they can increase their sense of well-being and trigger feelings of euphoria. As the impact diminishes, these effects wane. This often increases people’s desire to use the drug again. The risk of becoming addicted to drugs is high.

At a glance

  • Cannabis is the most commonly used illegal drug. Ecstasy, heroin, cocaine and crystal meth are used less often.
  • Drug use can cause physical and mental complications, such as cardiovascular disorders, seizures and anxiety.
  • Whether addiction develops depends on not only the substance but also social and personal factors. However, the risk of addiction is high with many drugs. 
  • Government measures are in place to prevent the use of drugs and the associated problems.
  • Several help services are available in the case of drug addiction.

Note: The information in this article cannot and should not replace a medical consultation and must not be used for self-diagnosis or treatment.

A packet of pills is passed from one person to another.

What are illegal drugs?

The term “illegal drugs” covers various groups of psychoactive substances, the procurement, possession and use of which are all legally prohibited. These include cannabis, ecstasy, cocaine and heroin, to name but a few. Psychoactive means that the use of these substances affects the human mind (psyche).

“Legal highs” are a special type of illegal drug, specifically new psychoactive substances (NPS) that have a similar effect to conventional drugs but are disguised and marketed as harmless incense blends or bath salts. Until 2016, the sale and use of legal highs in Germany was fully legal – hence their misleading name.

Many people use drugs for their intoxicating effect, i.e. their stimulating, euphoria-inducing properties. Other people take drugs to relax, relieve anxiety and inhibitions or escape reality.

Regular drug use in high doses can lead to addiction.

Drug use often causes a physical and mental dependency. In many cases, it also leads to other mental and physical conditions or even death.

Other addictive substances such as alcohol and nicotine also have psychoactive effects, can cause addiction and can result in long-term complications. However, these substances can still be legally purchased and consumed.

What illegal drugs are there and what are their properties?

There are many different illegal drugs. The most commonly used substances include:

  • amphetamines
  • cannabis
  • ecstasy
  • heroin
  • cocaine
  • methamphetamine
  • hallucinogens


Amphetamines are generally sold and used in tablet form or as white powder (“speed”). Their use increases people’s self-esteem, boosts their energy, makes them more sociable and enhances their mood, sometimes even causing euphoria. Taken in tablet form, the effect kicks in after about half an hour and lasts for several hours. Overdoses are indicated by cardiovascular issues, increased restlessness (agitation), confusion, mistrust and anxiety, impulsiveness and aggression. The risk of becoming addicted to amphetamines is high.


The term “cannabis” refers to substances obtained from the hemp plant. The flowers are often dried and offered as marijuana or grass. “Hashish” refers to the plant’s resin. Both are often crumbled up, mixed with tobacco and smoked as a joint. People who use hashish instead of grass absorb higher amounts of the intoxicating substance tetrahydrocannabinol (THC). THC increases the sense of well-being and enhances people’s moods, sometimes even causing euphoria. It can also cause drowsiness or laughter. The ability to think, memory, motor skills and sense of time are all affected. Long-term use can lead to severe apathy and lack of interest. People who use high doses of THC over prolonged periods can become psychologically addicted. If use is stopped after a prolonged period, physical withdrawal symptoms may occur.

Important: Since 2017, the use of cannabis for medicinal purposes has been legally permitted under certain conditions. Medical cannabis can be prescribed, for example, for chronic pain, nausea and vomiting or muscle cramps if previous treatment methods were not sufficiently successful. However, there is no clear scientific proof of the effectiveness of cannabis products. and they can also cause side effects.


Ecstasy is the common name for the chemical substance MDMA. It belongs to the group of methylenedioxymethamphetamines. Ecstasy is a widely used party drug, which is usually taken as a tablet. However, it can also be snorted or smoked. The effects of ecstasy kick in one to three hours after it has been taken and last for four to six hours. People who use ecstasy report effects such as greater self-confidence, increased alertness and sexual arousal, increased relaxation and feelings of happiness. Regular use can damage people’s health. It is also possible to become psychologically addicted to ecstasy. The probability of this is particularly high among people who react very strongly to the positive effects of the drug.


Chemically speaking, heroin 3,6-diacetylmorphine – a substance derived from morphine – is equivalent to a strong painkiller (opioid). The effect lasts for about 4 to 5 hours. Its chemical properties enable heroin to quickly enter the brain and reach high concentrations there, leading to the faster onset of euphoric feelings (the “kick”). Heroin is usually injected. The risk of psychological and physical addiction is high.

There are also two factors that make the use of heroin dangerous: the unknown concentration of heroin in the products purchased and the often unhygienic injection of the substance, for example due to the shared use of syringes. Potential consequences include an overdose, heart valve disorders or infectious diseases such as hepatitis and HIV.


Cocaine is produced from the leaves of the coca plant, which are processed to form a paste containing 80 percent pure cocaine. This is then used to create a white powder (cocaine hydrochloride), which can be swallowed, snorted or injected. Cocaine use enhances the mood, triggers feelings of euphoria and enhanced performance, increases activity and curbs hunger and tiredness. The risk of addiction to cocaine is high. When the effect of cocaine wears off, the euphoria often switches to feelings of depression. This in turn increases the desire to use more cocaine, thereby increasing the risk of becoming addicted.


This substance is found in powder form (“crystal speed”) and crystal form (“crystal meth”). Depending whether it is snorted, swallowed or injected, it can take a few seconds to a few minutes to start taking effect and then lasts between 6 and 48 hours. Using methamphetamine makes people more sociable, curbs their appetite and prevents them from falling asleep. When these effects wane, irritability, restlessness, anxiety, depressive symptoms and apathy may ensue. Many people only use methamphetamine on an occasional basis and do not become addicted. Anyone who uses the substance repeatedly and for several days, however, is at greater risk of becoming addicted. This is because the euphoric phase (“run”) is followed by a comedown period (“crash”), which is characterized by an increased desire for the substance. The risk of psychological addiction is particularly high.


LSD (lysergic acid diethylamide) is one of the best-known artificially produced hallucinogens. The starter substance lysergic acid is obtained from the ergot fungus. There are other types of fungi that contain the active substance psilocybin. This is broken down in the body to form the psychoactive substance psilocin. The fungus can be eaten either raw or dried or drunk as an infusion. When consumed in certain quantities, the fungus causes LSD-like intoxication with anxiety (“horror trips”). Unlike with LSD, there is no evidence of fungi containing psilocybin causing flashbacks. Flashbacks are when hallucinogenic effects persist a long time after taking a drug (when the actual effect has already finished).

How many people use illegal drugs?

In Germany, about one in three people use an illegal drug at some point in life.

Drug usage often starts during adolescence or early adulthood. According to study data from 2019, one in ten young people aged 12 to 17 have already used an illegal drug at some point. The same applies to almost half of 18 to 25-year-olds.

Almost one in two people aged between 18 and 25 have used illegal drugs at some point.

The most commonly used substance is cannabis. The number of users increases continuously from late childhood to young adulthood. More boys and young men use cannabis than girls and young women.

The use of other substances such as ecstasy, LSD, heroin, cocaine, crystal meth or hallucinogens is much less common.

What factors increase the risk of drug abuse and drug addiction?

Whether the occasional use of illegal drugs develops into misuse or addiction depends on the substance type and the frequency of use as well as physical, mental and social factors.

For example, if people grow up with parents or siblings who use drugs or have friends who do so, there is a higher probability of them turning to drugs themselves. Traumatic events such as child abuse can also lead to drug use as a coping strategy.

The extent to which a drug’s effect is perceived as an emotional benefit also plays an important role. The greater the perceived benefit, the greater the likelihood that the substance will be re-used.

Other factors that increase the risk of drug abuse include:

  • low self-control and self-esteem
  • negative mood
  • social behavior problems
  • a lack of problem-solving strategies
  • loss of interest, e.g. in schoolwork
  • a desire for sensation and to cross boundaries

How do illegal drugs work?

Illegal drugs interfere with the brain metabolism by influencing the transmission of stimulus signals from one nerve cell to another.

Illegal drugs influence the transmission of stimulus signals from one nerve cell to another.

The transmission of stimuli is mediated by messengers (neurotransmitters). The body’s own neurotransmitters include dopamine and serotonin.

Depending on the type of substance used, drugs can influence the transmission of stimuli in various ways.

For instance, the use of amphetamines and methamphetamine causes the release of higher amounts of the messenger substance dopamine, enhancing people’s mood.

Substances such as cocaine, on the other hand, prevent dopamine and serotonin from being absorbed back into the emitting nerve cell. As a result, larger amounts of dopamine and serotonin are freely available, which also increases feelings of happiness.

In the case of hallucinogens such as LSD, the effect is based on the fact that LSD is structurally similar to serotonin and imitates the effect of this messenger substance.

The effect of cannabis is based on the addictive substance THC contained in cannabis binding to cannabinoid receptors, which leads to an increased release of dopamine.

Opiates such as heroin take effect by activating opiate receptors – special docking points in the brain. This enhances positive sensations and inhibits pain, for example.

What are the potential consequences of using illegal drugs?

Regular drug use can cause addiction, which is, in turn, associated with several physical and mental complications. A drug overdose or an unfavorable combination of different addictive substances can also result in death.

Existence of addiction

There are six internationally valid criteria that can be used to determine the existence of addiction:

  • a strong desire or urge to use an addictive substance
  • an increasing loss of control over the start and end of use and the amount of the addictive substance used
  • the presence of physical withdrawal symptoms after stopping or reducing use
  • the existence of tolerance: ever higher amounts of the addictive substance are needed to achieve the desired effect.
  • increased neglect of other pleasures or interests in favor of substance use; increased time spent obtaining the drug or recovering from the effects of use
  • persistent substance use despite the existence of physical, mental or social consequences

If three or more of these criteria were met over the last year, addiction exists. If fewer than three criteria are met but the effects of the drug use are already noticeable, this is classified as harmful use.

Physical effects

Persistent use of amphetamines, cocaine and ecstasy is associated with cardiovascular problems such as high blood pressure and palpitations. In high doses, amphetamine and cocaine can cause cardiac arrest and sudden cardiac death. People who use amphetamines are also at a higher risk of heart attacks and strokes. The serious consequences of ecstasy also include a high body temperature (hyperthermia) and dehydration, kidney and liver failure and circulatory failure.

Taking methamphetamine can also lead to hyperthermia. A heightened risk particularly exists in extremely warm environments where people are also exerting themselves physically, for example when dancing in a club. Using high doses of methamphetamine can lead to problems such as severe weight loss, eating disorders, stomach pain, skin inflammation (“speed spots”), oral thrush and tooth loss.

In pure form, heroin does not cause any direct organ damage. However, people who are not accustomed to the substance can respond to just 5 milligrams with a loss of consciousness, slowed breathing (respiratory depression), a slowed heart rate and circulatory failure, which can be fatal in the event of an overdose.

Drugs like amphetamines and cocaine also trigger seizures. If drugs are injected into the veins and good hygiene is not observed, the risk of infectious diseases such as hepatitis B, hepatitis C and HIV increases.

Important: People with statutory health insurance aged 35 and over are eligible for a one-off test for hepatitis B and hepatitis C as part of the health check-up. This is particularly important for people who inject drugs. Furthermore, drug services offer anonymous rapid tests for hepatitis C and HIV as well as vaccinations against hepatitis.

Mental effects

Regular cannabis use affects the performance of the brain, i.e. cognitive abilities. The longer and more intensively cannabis is used, the more the memory, concentration and ability to learn are impaired. The brain is particularly severely affected in people who start to use cannabis at a young age. The probability of the drug use triggering psychoses is increased.

Many people who are addicted to opiates such as heroin develop depression, anxiety or a personality disorder at some point in their life. Their risk of developing any of these mental disorders is significantly higher than that of people who are not addicted to drugs.

Cocaine use can cause confusion, impaired consciousness and even coma. The use of amphetamines, LSD and marijuana can trigger paranoid delusions. Ecstasy is associated with major states of anxiety (“horror trips”) and psychotic disorders, for example.

Persistent use of methamphetamine may cause severe itching and micro-hallucinations – the feeling of ants or beetles crawling under the skin experienced by the drug user. Doctors refer to this condition as delusional parasitosis.

The use of hallucinogens can cause a lasting perception disorder, also known as hallucinogen-persisting perception disorder (HPPD). HPPD exists when people experience flashbacks in the form of seemingly moving objects, intensive colors or bright, geometric shapes, and these affect everyday life to an extent where medical assistance is required.

Drug-related deaths

In 2021, 1,826 deaths were recorded in Germany as a result of the use of illegal drugs. In 2020, 1,581 people died from drug use. The most common causes were an overdose of opioids such as heroin or the combined use of several substances.

How can drug abuse and drug addiction be prevented?

There are several governmental measures for preventing addiction. Drug and addiction policy aims to reduce the use of all types of drugs and to prevent drug and addiction-induced social and health problems.

The most important measures for preventing and combating drug use are:

  • providing information about the dangers of drug use, for example through campaigns in schools
  • promoting stable personalities for children and adolescents, for example through well-equipped daycare facilities, smaller school classes and sports facilities
  • strengthening and maintaining counseling and treatment services as well as quitting assistance
  • stabilizing the health and social situation of the addict through the use of survival aids and damage limitation measures, such as drug-use rooms or drug replacement therapy for heroin addiction
  • restricting the availability of drugs through legislation and the fight against drug crime

What is the aim of treatment for drug addiction?

The treatment of people with a drug addiction has several aims:

  • preserving life in phases of acute drug use
  • preventing long-term physical effects
  • individually tailored sociotherapeutic and psychotherapeutic treatment and strengthening of the potential for self-help
  • safeguarding the social environment and preventing social exclusion and discrimination
  • achieving longer periods of abstinence
  • constructive processing of relapses
  • therapeutic treatment of the addiction
  • professional and social integration

To achieve the aims, it is important that the person with the addiction is able to:

  • accept the existence of the addiction and admit a need for change
  • develop the motivation for treatment and accept the offer of assistance
  • accept the aim of abstinence

Germany has a comprehensive medical and psychosocial assistance system for implementing the aims. This comprises six pillars:

  • Acute assistance through low-level services such as places to sleep. These often offer basic medical care.
  • Outpatient counseling and treatment: these are available from special addiction and drug counseling facilities.
  • Drug withdrawal in hospital: the body is detoxified from the substance. If the withdrawal is accompanied by psychosocial care, this is referred to as qualified detoxification.
  • Care using the seamless model: this describes the seamless transition from acute detoxification to inpatient therapy.
  • Transitional care: the link between outpatient and inpatient care. This should offer people a rest period and time to make further treatment decisions.
  • Substitution and psychosocial counseling: the interface between medical substitution therapy and the drug assistance system, especially for people with a heroin addiction. According to the substitution register, about 80,000 people are permanently in therapy.
  • Treatment within the scope of addiction rehabilitation: this takes place over several months in an outpatient, day patient or inpatient capacity, partly using substitution therapy.
  • Aftercare: this takes place in either a day patient or an outpatient capacity. The services include educational and professional training opportunities to support the route to a low-drug or drug-free life.

Important: Psychotherapeutic treatments play a central role in both outpatient and inpatient withdrawal treatment. The best researched and most effective form of psychotherapy for addiction treatment is cognitive behavioral therapy.

What addiction advice options are available?

People with drug problems and their relatives can obtain assistance from addiction advice centers throughout Germany. These have a team of experts from the fields of medicine, psychology, social education and social work. All employees are subject to confidentiality obligations.

The website of the German Center for Addiction Issues (Deutsche Hauptstelle für Suchtfragen e.V. – DHS) offers a directory of addiction support where you can find suitable services near you.

The website DigiSucht offers online advice about addiction. People affected by addiction and their loved ones will find answers there about drugs, substance use, gambling and media consumption.

Self-help groups support and promote exchanges with other people who have had similar experiences in dealing with illegal drugs or relatives with an addiction problem.

You can find suitable self-help via a database on the National Contact and Information Point For Encouraging and Supporting Self-Help Groups (NAKOS) website.

Where else can information be obtained about drugs and drug addiction?

Further information on drugs and their effects can be found in the drugs glossary provided by The Federal Center for Health Education (Bundeszentrale für gesundheitliche Aufklärung – BZgA) – in German only.

The Federal Center for Health Education (BZgA) offers further information about the prevention of cannabis use under (in German only). The information is aimed at adolescents, parents, teachers and educational specialists.

Reviewed by the Professional Association for Addiction (Fachverband Sucht+ e.V.).

As at:
Did you find this article helpful?