In order to maintain high-quality performance, some musicians take chemical substances. Some musicians take drugs or alcohol to deal with the stress of performing. As a group they have a higher rate of substance abuse. The most common chemical substance which is abused by pop musicians is cocaine, because of its neurological effects. Stimulants like cocaine increase alertness and cause feelings of euphoria, and can therefore make the performer feel as though they in some ways ‘own the stage’. One way in which substance abuse is harmful for a performer (musicians especially) is if the substance being abused is aspirated. The lungs are an important organ used by singers, and addiction to cigarettes may seriously harm the quality of their performance. Smoking causes harm to alveoli, which are responsible for absorbing oxygen.

Street children in many developing countries are a high risk group for substance misuse, in particular solvent abuse. Drawing on research in Kenya, Cottrell-Boyce argues that "drug use amongst street children is primarily functional – dulling the senses against the hardships of life on the street – but can also provide a link to the support structure of the ‘street family’ peer group as a potent symbol of shared experience."

Alcohol abuse is said to be most common in people aged between 15 and 24 years, according to Moreira 2009. However, this particular study of 7275 college students in England collected no comparative data from other age groups or countries.

Causes of alcohol abuse are complex and are likely the combination of many factors, from coping with stress to childhood development. The US Department of Health & Human Services identifies several factors influencing adolescent alcohol use, such as risk-taking, expectancies, sensitivity and tolerance, personality and psychiatric comorbidity, hereditary factors, and environmental aspects. Studies show that child maltreatment such as neglect, physical, and/or sexual abuse, as well as having parents with alcohol abuse problems, increases the likelihood of that child developing alcohol use disorders later in life. According to Shin, Edwards, Heeren, & Amodeo (2009), underage drinking is more prevalent among teens that experienced multiple types of childhood maltreatment regardless of parental alcohol abuse, putting them at a greater risk for alcohol use disorders. Genetic and environmental factors play a role in the development of alcohol use disorders, depending on age. The influence of genetic risk factors in developing alcohol use disorders increase with age ranging from 28% in adolescence and 58% in adults.

Complications of benzodiazepine abuse include drug-related deaths due to overdose especially in combination with other depressant drugs such as opioids. Other complications include: blackouts and memory loss, paranoia, violence and criminal behaviour, risk-taking sexual behaviour, foetal and neonatal risks if taken in pregnancy, dependence, withdrawal seizures and psychosis. Injection of the drug carries risk of: thrombophlebitis, deep vein thrombosis, deep and superficial abscesses, pulmonary microembolism, rhabdomyolysis, tissue necrosis, gangrene requiring amputation, hepatitis B and C, as well as blood borne infections such as HIV infection (caused by sharing injecting equipment). Long-term use of benzodiazepines can worsen pre-existing depression and anxiety and may potentially also cause dementia with impairments in recent and remote memory functions.

Use is widespread among amphetamine users, with those that use amphetamines and benzodiazepines having greater levels of mental health problems and social deterioration. Benzodiazepine injectors are almost four times more likely to inject using a shared needle than non-benzodiazepine-using injectors. It has been concluded in various studies that benzodiazepine use causes greater levels of risk and psycho-social dysfunction among drug misusers.

Poly-drug users who also use benzodiazepines appear to engage in more frequent high-risk behaviors. Those who use stimulant and depressant drugs are more likely to report adverse reactions from stimulant use, more likely to be injecting stimulants and more likely to have been treated for a drug problem than those using stimulant but not depressant drugs.

Individuals with a substance abuse history are at an increased risk of misusing benzodiazepines.

Several (primary research) studies, even into the last decade, claimed, that individuals with a history of familial abuse of alcohol or who are siblings or children of alcoholics appeared to respond differently to benzodiazepines than so called "genetically healthy" persons, with males experiencing increased euphoric effects and females having exaggerated responses to the adverse effects of benzodiazepines.

Whilst all benzodiazepines have abuse potential, certain characteristics increase the potential of particular benzodiazepines for abuse. These characteristics are chiefly practical ones—most especially, availability (often based on popular perception of 'dangerous' versus 'non-dangerous' drugs) through prescribing physicians or illicit distributors. Pharmacological and pharmacokinetic factors are also crucial in determining abuse potentials. A short elimination half-life, high potency and a rapid onset of action are characteristics which increase the abuse potential of benzodiazepines. The following table provides the elimination half-life, relevant potency to other benzodiazepines, speed of onset of action and duration of behavioural effects.

The cause of alcohol abuse is complex. Alcohol abuse is related to economic and biological origins and is associated with adverse health consequences. Peer pressure influences individuals to abuse alcohol; however, most of the influence of peers is due to inaccurate perceptions of the risks of alcohol abuse. According to Gelder, Mayou and Geddes (2005) easy accessibility of alcohol is one of the reasons people engage in alcohol abuse as this substance is easily obtained in shops. Another influencing factor among adolescents and college students are the perceptions of social norms for drinking; people will often drink more to keep up with their peers, as they believe their peers drink more than they actually do. They might also expect to drink more given the context (e.g. sporting event, fraternity party, etc.). This perception of norms results in higher alcohol consumption than is normal.

Alcohol abuse is also associated with acculturation, because social and cultural factors such as an ethnic group’s norms and attitudes can influence alcohol abuse.

The impact of alcohol on weight-gain is contentious: some studies find no effect, others find decreased or increased effect on weight gain.

Alcohol use increases the risk of chronic gastritis (stomach inflammation); it is one cause of cirrhosis, hepatitis, and pancreatitis in both its chronic and acute forms.

As demonstrated by the chart below, numerous studies have examined factors which mediate substance abuse or dependence. In these examples, the predictor variables lead to the mediator which in turn leads to the outcome, which is always substance abuse or dependence. For example, research has found that being raised in a single-parent home can lead to increased exposure to stress and that increased exposure to stress, not being raised in a single-parent home, leads to substance abuse or dependence. The following are some, but by no means all, of the possible mediators of substance abuse.

As demonstrated by the chart below, numerous studies have examined factors which moderate substance abuse or dependence. In these examples, the moderator variable impacts the level to which the strength of the relationship varies between a given predictor variable and the outcome of substance abuse or dependence. For example, there is a significant relationship between psychobehavioral risk factors, such as tolerance of deviance, rebelliousness, achievement, perceived drug risk, familism, family church attendance and other factors, and substance abuse and dependence. That relationship is moderated by familism which means that the strength of the relationship is increased or decreased based on the level of familism present in a given individual.

Examples of mediators and moderators can be found in several empirical studies. For example, Pilgrim et al.’s hypothesized mediation model posited that school success and time spent with friends mediated the relationship between parental involvement and risk-taking behavior with substance use (2006). More specifically, the relationship between parental involvement and risk-taking behavior is explained via the interaction with third variables, school success and time spent with friends. In this example, increased parental involvement led to increased school success and decreased time with friends, both of which were associated with decreased drug use. Another example of mediation involved risk-taking behaviors. As risk-taking behaviors increased, school success decreased and time with friends increased, both of which were associated with increased drug use.

A second example of a mediating variable is depression. In a study by Lo and Cheng (2007), depression was found to mediate the relationship between childhood maltreatment and subsequent substance abuse in adulthood. In other words, childhood physical abuse is associated with increased depression, which in turn, in associated with increased drug and alcohol use in young adulthood. More specifically, depression helps to explain how childhood abuse is related to subsequent substance abuse in young adulthood.

A third example of a mediating variable is an increase of externalizing symptoms. King and Chassin (2008) conducted research examining the relationship between stressful life events and drug dependence in young adulthood. Their findings identified problematic externalizing behavior on subsequent substance dependency. In other words, stressful life events are associated with externalizing symptoms, such as aggression or hostility, which can lead to peer alienation or acceptance by socially deviant peers, which could lead to increased drug use. The relationship between stressful life events and subsequent drug dependence however exists via the presence of the mediation effects of externalizing behaviors.

An example of a moderating variable is level of cognitive distortion. An individual with high levels of cognitive distortion might react adversely to potentially innocuous events, and may have increased difficulty reacting to them in an adaptive manner (Shoal & Giancola, 2005). In their study, Shoal and Giancola investigated the moderating effects of cognitive distortion on adolescent substance use. Individuals with low levels of cognitive distortion may be more apt to choose more adaptive methods of coping with social problems, thereby potentially reducing the risk of drug use. Individuals with high levels of cognitive distortions, because of their increased misperceptions and misattributions, are at increased risk for social difficulties. Individuals may be more likely to react aggressively or inappropriately, potentially alienating themselves from their peers, thereby putting them at greater risk for delinquent behaviors, including substance use and abuse. In this study, social problems are a significant risk factor for drug use when moderated by high levels of cognitive distortions.

A study concluded, "Mild to moderate alcohol consumption is associated with a lower prevalence of the metabolic syndrome, with a favorable influence on lipids, waist circumference, and fasting insulin. This association was strongest among whites and among beer and wine drinkers." This is also true for Asians. A J-curve association between alcohol intake and metabolic syndrome was found: "The results of the present study suggest that the metabolic syndrome is negatively associated with light alcohol consumption (1–15 g alcohol/d) in Korean adults". However, "odds ratios for the metabolic syndrome and its components tended to increase with increasing alcohol consumption."

Based on combined data from SAMHSA's 2004–2005 National Surveys on Drug Use & Health, the rate of past-year alcohol dependence or abuse among persons aged 12 or older varied by level of alcohol use: 44.7% of past month heavy drinkers, 18.5% binge drinkers, 3.8% past month non-binge drinkers, and 1.3% of those who did not drink alcohol in the past month met the criteria for alcohol dependence or abuse in the past year. Males had higher rates than females for all measures of drinking in the past month: any alcohol use (57.5% vs. 45%), binge drinking (30.8% vs. 15.1%), and heavy alcohol use (10.5% vs. 3.3%), and males were twice as likely as females to have met the criteria for alcohol dependence or abuse in the past year (10.5% vs. 5.1%).

A study consisting of 1,081 U.S. residents who had first used cocaine within the previous 24 months was conducted. It was found that the risk of becoming dependent on cocaine within two years of first use was 5–6%. The risk of becoming dependent within 10 years of first use increased to 15–16%. These were the aggregate rates for all types of use considered, such as smoking, snorting, and injecting. Among recent-onset users individual rates of dependency were higher for smoking (3.4 times) and much higher for injecting. Women were 3.3 times more likely to become dependent, compared with men. Users who started at ages 12 or 13 were four times as likely to become dependent compared to those who started between ages 18 and 20.

However, a study of non-deviant users in Amsterdam found a "relative absence of destructive and compulsive use patterns over a ten year period" and concluded that cocaine users can and do exercise control. "Our respondents applied two basic types of controls to themselves: 1) restricting use to certain situations and to emotional states in which cocaine's effects would be most positive, and 2) limiting mode of ingestion to snorting of modest amounts of cocaine, staying below 2.5 grams a week for some, and below 0.5 grams a week for most. Nevertheless, those whose use level exceeded 2.5 grams a week all returned to lower levels".

The dependence potential of a drug varies from substance to substance, and from individual to individual. Dose, frequency, pharmacokinetics of a particular substance, route of administration, and time are critical factors for developing a drug dependence.

An article in "The Lancet" compared the harm and dependence liability of 20 drugs, using a scale from zero to three for physical dependence, psychological dependence, and pleasure to create a mean score for dependence. Selected results can be seen in the chart below.

Withdrawal is the body's reaction to abstaining from a substance upon which a person has developed a dependence syndrome. When dependence has developed, cessation of substance use produces an unpleasant state, which promotes continued drug use through negative reinforcement; i.e., the drug is used to escape or avoid re-entering the associated withdrawal state. The withdrawal state may include physical-somatic symptoms (physical dependence), emotional-motivational symptoms (psychological dependence), or both. Chemical and hormonal imbalances may arise if the substance is not introduced. Psychological stress may also result if the substance is not re-introduced.

Infants also suffer from substance withdrawal, known as Neonnatal Abstinence Syndrome (NAS) which has severe and life-threatening effects on growing fetus. Addiction to drugs and alcohol in expecting mothers does not only cause NAS but also an array of other issues which can continually affect the infant throughout his/her lifetime. The type of drug which was abused during the months of pregnancy has many different effects on the child which can affect the infant in many ways throughout his/her life.

A complex mixture of genetic and environmental factors influences the risk of the development of alcoholism. Genes that influence the metabolism of alcohol also influence the risk of alcoholism, and may be indicated by a family history of alcoholism. One paper has found that alcohol use at an early age may influence the expression of genes which increase the risk of alcohol dependence. Individuals who have a genetic disposition to alcoholism are also more likely to begin drinking at an earlier age than average. Also, a younger age of onset of drinking is associated with an increased risk of the development of alcoholism, and about 40 percent of alcoholics will drink excessively by their late adolescence. It is not entirely clear whether this association is causal, and some researchers have been known to disagree with this view.

Severe childhood trauma is also associated with a general increase in the risk of drug dependency. Lack of peer and family support is associated with an increased risk of alcoholism developing. Genetics and adolescence are associated with an increased sensitivity to the neurotoxic effects of chronic alcohol abuse. Cortical degeneration due to the neurotoxic effects increases impulsive behaviour, which may contribute to the development, persistence and severity of alcohol use disorders. There is evidence that with abstinence, there is a reversal of at least some of the alcohol induced central nervous system damage. The use of cannabis was associated with later problems with alcohol use. Alcohol use was associated with an increased probability of later use of tobacco, cannabis, and other illegal drugs.

Some medical systems, including those of at least 15 states of the United States, refer to an Addiction Severity Index to assess the severity of problems related to substance use. According to DARA Thailand, the index assesses potential problems in seven categories: medical, employment/support, alcohol, other drug use, legal, family/social, and psychiatric.

In the United States, cocaine use results in about 5,000–6,000 deaths annually.

Medical organizations strongly discourage drinking alcohol during pregnancy. Alcohol passes easily from the mother's bloodstream through the placenta and into the bloodstream of the fetus, which interferes with brain and organ development. Alcohol can affect the fetus at any stage during pregnancy, but the level of risk depends on the amount and frequency of alcohol consumed. Regular heavy drinking and binge drinking (four or more drinks on any one occasion) pose the greatest risk for harm, but lesser amounts can cause problems as well. There is no known safe amount or safe time to drink during pregnancy.

Prenatal alcohol exposure can lead to fetal alcohol spectrum disorders (FASDs). The most severe form of FASD is fetal alcohol syndrome (FAS). Problems associated with FASD include facial anomalies, low birth weight, stunted growth, small head size, delayed or uncoordinated motor skills, hearing or vision problems, learning disabilities, behavior problems, and inappropriate social skills compared to same-age peers. Those affected are more likely to have trouble in school, legal problems, participate in high-risk behaviors, and develop substance use disorders themselves.

A study published in the British Medical Journal on 10 July 2014 investigated the correlation between human variants of the ADH1B gene, which codes for the ADH1B enzyme (Alcohol dehydrogenase 1B), and cardiovascular health. The study concluded that carriers of one specific variant of this gene (A-allele of ADH1B rs1229984), which is associated with lower alcohol consumption, '...had a more favourable cardiovascular profile and a reduced risk of coronary heart disease than those without the genetic variant.' The study's authors extrapolated from this finding to suggest that '...reduction of alcohol consumption, even for light to moderate drinkers, is beneficial to health.'

This study contradicts previous findings on the causal relationship between light alcohol consumption and cardiovascular health, and has been criticized on its methodology by members of the International Scientific Forum on Alcohol Research, which stated in its analysis that '...[there are] questions about making generalized statements about the effects of alcohol on disease based on results from the analysis of a single nucleotide polymorphism of a gene.'

Moreover, the study fails to explain or discount previous findings that show a causal link between alcohol intake and cardiovascular health that can not be accounted for by genetic predisposition alone.

Research studies have come to different conclusions on the number of therapeutic dose users who develop a physical dependence and withdrawal syndrome. Estimates by researchers of the number of people affected range 20–100% of patients prescribed benzodiazepines at therapeutic dosages long term are physically dependent and will experience withdrawal symptoms.

Benzodiazepines can be addictive and induce dependence even at low doses, with 23% becoming addicted within 3 months of use. Benzodiazepine addiction is considered a public health problem. Approximately 68.5% of prescriptions of benzodiazepines originate from local health centers, with psychiatry and general hospitals accounting for 10% each. A survey of general practitioners reported that the reason for initiating benzodiazepines was due to an empathy for the patients suffering and a lack of other therapeutic options rather than patients demanding them. However, long-term use was more commonly at the insistence of the patient, it is presumed, because physical dependence or addiction had developed.

Approximately twice as many women as men are prescribed benzodiazepines. It is believed that this is largely because men typically turned to alcohol to cope with stress and women to prescription drugs. Biased perception of women by male doctors may also play a role in increased prescribing rates to women; however, increased anxiety features in women does not account for the wide gap alone between men and women.

A study published in the British Journal of General Practice in July 2017 found that in a sample taken from a survey conducted in 2014–2015 in Bradford a mean of 0.69% of registered patients had been prescribed benzodiazepines for more than a year. This would suggest that there were around 300,000 long-term users of diazepine in the UK.

Male anabolic-androgenic steroid abusers often have a troubled social background.

The National Institute on Drug Abuse (NIDA) says that "even though anabolic steroids do not cause the same high as other drugs, steroids are reinforcing and can lead to addiction. Studies have shown that animals will self-administer steroids when given the opportunity, just as they do with other addictive drugs. People may persist in abusing steroids despite physical problems and negative effects on social relationships, reflecting these drugs’ addictive potential. Also, steroid abusers typically spend large amounts of time and money obtaining the drug; another indication of addiction. Individuals who abuse steroids can experience withdrawal symptoms when they stop taking them, including mood swings, fatigue, restlessness, loss of appetite, insomnia, reduced sex drive, and steroid cravings, all of which may contribute to continued abuse. One of the most dangerous withdrawal symptoms is depression. When depression is persistent, it can sometimes lead to suicidal thoughts. Research has found that some steroid abusers turn to other drugs such as opioids to counteract the negative effects of steroids."

There are many potential complications that can arise due to substance abuse such as severe physiological damage, psychological changes and social changes that are often not desirable.

Physiological damage is often the most obvious, observed as an abnormal condition affecting the body of an organism: For instance, there are several known alcohol-induced diseases (e.g. alcoholic hepatitis, alcoholic liver disease, alcoholic cardiomyopathy.) Substance abuse is also often associated with premature ageing, fertility complications, brain damage and a higher risk of infectious diseases due to a weakened immune system.

Long term abuse has been linked to personality changes such as depression, paranoia, anxiety which can be related to psychological disorders. It is often reported that substance abuse coincides with personality disorders, such as borderline personality disorder. It has also now been linked to severe brain damage leading to an inability to control behaviours, which could explain why many people who abuse substances go on to develop addictions.

Substance abuse is often regarded as negative in society and therefore those who engage in such behaviours can often be subject to social discrimination. The use of many drugs can lead to criminal convictions, whether the drug itself is illegal or abusers use unlawful methods to fund their substances. It is also more likely that someone will partake in criminal or anti-social behaviour when they are under the influence of a drug.

Amphetamine dependence refers to a state of psychological dependence on a drug in the amphetamine class. In individuals with substance use disorder (problematic use or abuse with dependence), psychotherapy is currently the best treatment option as no pharmacological treatment has been approved. Tolerance is expected to develop with regular substituted amphetamine use. When substituted amphetamines are abused, drug tolerance develops rapidly.

Severe withdrawal associated with dependence from recreational substituted amphetamine use can be difficult for a user to cope with. Long-term use of certain substituted amphetamines, particularly methamphetamine, can reduce dopamine activity in the brain. Psychostimulants that increase dopamine and mimic the effects of substituted amphetamines, but with lower abuse liability, could theoretically be used as replacement therapy in amphetamine dependence. However, the few studies that used amphetamine, bupropion, methylphenidate and modafinil as a replacement therapy did not result in less methamphetamine use or craving.

In 2013, overdose on amphetamine, methamphetamine, and other compounds implicated in an "amphetamine use disorder" resulted in an estimated 3,788 deaths worldwide (3,425–4,145 deaths, 95% confidence).

Benzodiazepines are one of the largest classes of abused drugs; they are classed as schedule IV controlled drugs because of their recognized medical uses. Across the world the most frequently diverted and abused benzodiazepines include temazepam, diazepam, nimetazepam, nitrazepam, triazolam, flunitrazepam, midazolam, and in the United States alprazolam, clonazepam, and lorazepam.

Benzodiazepines can cause serious addiction problems. A survey of doctors in Senegal found that many doctors feel that their training and knowledge of benzodiazepines is, in general, poor; a study in Dakar found that almost one-fifth of doctors ignored prescribing guidelines regarding short-term use of benzodiazepines, and almost three-quarters of doctors regarded their training and knowledge of benzodiazepines to be inadequate. More training regarding benzodiazepines has been recommended for doctors. Due to the serious concerns of addiction, national governments were recommended to urgently seek to raise knowledge via training about the addictive nature of benzodiazepines and appropriate prescribing of benzodiazepines.

A six-year study on 51 Vietnam veterans who were drug abusers of either mainly stimulants (11 people), mainly opiates (26 people), or mainly benzodiazepines (14 people) was carried out to assess psychiatric symptoms related to the specific drugs of abuse. After six years, opiate abusers had little change in psychiatric symptomatology; five of the stimulant users had developed psychosis, and eight of the benzodiazepine users had developed depression. Therefore, long-term benzodiazepine abuse and dependence seems to carry a negative effect on mental health, with a significant risk of causing depression. Benzodiazepines are also sometimes abused intra-nasally.

In the elderly, alcohol and benzodiazepines are the most commonly abused substances, and the elderly population is more susceptible to benzodiazepine withdrawal syndrome and delirium than are younger patients.

Comorbidity of addictive disorders and other psychiatric disorders, i.e., dual disorders, is very common and a large body of literature has accumulated demonstrating that mental disorders are strongly associated with substance use disorders. The 2011 USA National Survey on Drug Use and Health found that 17.5% of adults with a mental illness had a co-occurring substance use disorder; this works out to 7.98 million people. Estimates of co-occurring disorders in Canada are even higher, with an estimated 40-60% of adults with a severe and persistent mental illness experiencing a substance use disorder in their lifetime.

A study by Kessler et al. in the United States attempting to assess the prevalence of dual diagnosis found that 47% of clients with schizophrenia had a substance misuse disorder at some time in their life, and the chances of developing a substance misuse disorder was significantly higher among patients suffering from a psychotic illness than in those without a psychotic illness.

Another study looked at the extent of substance misuse in a group of 187 chronically mentally ill patients living in the community. According to the clinician's ratings, around a third of the sample used alcohol, street drugs, or both during the six months before evaluation.

Further UK studies have shown slightly more moderate rates of substance misuse among mentally ill individuals. One study found that individuals suffering from schizophrenia showed just a 7% prevalence of problematic drug use in the year prior to being interviewed and 21% reported problematic use some time before that.

Wright and colleagues identified individuals with psychotic illnesses who had been in contact with services in the London borough of Croydon over the previous 6 months. Cases of alcohol or substance misuse and dependence were identified through standardized interviews with clients and keyworkers. Results showed that prevalence rates of dual diagnosis were 33% for the use of any substance, 20% for alcohol misuse only and 5% for drug misuse only. A lifetime history of any illicit drug use was observed in 35% of the sample.