Aversion Therapy

Aversion therapy is a behavioral therapy technique to reduce unwanted behavior.

Aversion therapy works by pairing together the stimulus that can cause deviant behavior (such as an alcoholic drink or cigarette) with some form of unpleasant (aversive) stimulus, such as an electric shock or nausea-inducing drug.

With repeated presentations, the two stimuli become associated, and the person develops an aversion towards the stimuli which initially caused the deviant behavior.

Aversion therapy is based on classical conditioning. According to learning theory, two stimuli become associated when they frequently occur together (pairing). For example, in addiction, the drug, alcohol, or behavior in the case of gambling becomes associated with pleasure and high arousal.

Aversion therapy uses the same principle but changes the association and replaces the pleasure with an unpleasant state (counterconditioning).

Alcohol Addiction

Aversion therapy has been used effectively for years in the treatment of alcoholism (Davidson, 1974; Elkins, 1991; Streeton & Whelan, 2001).

Patients are given an aversive drug which causes vomiting-emetic drug. They start experiencing nausea; at this point, they are given a drink smelling strongly of alcohol, and they start vomiting almost immediately. The treatment is repeated with a higher dose of the drug.

Another treatment involves the use of disulfiram (e.g., Antabuse). This drug interferes with the metabolism of alcohol. Normally alcohol is broken down into acetaldehyde and then into acetic acid (vinegar).

Disulfiram prevents the second stage from occurring, leading to a very high level of acetaldehyde which is the main component of hangovers. This results in severe throbbing headaches, increased heart rate, palpitations, nausea, and vomiting.

Gambling addiction

For behavioral addiction, such as gambling, aversion therapy involves associating such stimuli and behavior with a very unpleasant unconditioned stimulus, such as an electric shock. These shocks are painful but do not cause damage.

The gambler creates cue cards with key phrases they associate with their gambling and then similar cards for neutral statements.

As they read through the statements, they administer a two-second electric shock for each gambling-related statement. The patient set the intensity of the shock themselves, aiming to make the shock painful but distressing.

The client thus learns to associate the undesirable behavior with the electric shock, and a link is formed between the undesirable behavior and the reflex response to an electric shock.

Critical Evaluation

There are ethical issues associated with the use of aversion therapy, such as physical harm (vomiting can lead to electrolyte unbalance) and loss of dignity; for this reason, covert sensitization is now preferred to aversion therapy.

Compliance with the treatment is low due to the unpleasant nature of the stimuli used, e.g., inducing violent vomiting.

Apart from ethical considerations, there are two other issues relating to the use of aversion therapy.

First, it is not very clear how the shocks or drugs have their effects.  It may be that they make the previously attractive stimulus (e.g., sight/smell/taste of alcohol) aversive, or it may be that they inhibit (i.e., reduce) the behavior of drinking.

Second, there are doubts about the long-term effectiveness of aversion therapy.  It can have dramatic effects in the therapist’s office.  However, it is often much less effective in the outside world, where no nausea-inducing drug has been taken, and it is obvious that no shocks will be given.

Also, relapse rates are very high – the success of the therapy depends on whether the patient can avoid the stimulus they have been conditioned against.

Away from the controlled environment where the associations between behavior/drug and unpleasant stimuli are formed, it is common for addictions to return.

Chesser (1976) found that with aversion therapy, 50% of alcoholics abstained for at least a year and that the treatment was more successful than no treatment. This supports the effectiveness of interventions based on classical conditioning.

However, Hajek and Stead (2013) reviewed 25 studies on the effectiveness of aversion therapy. They found that all but one had significant methodological flaws, meaning their results must be treated cautiously.

Behavioral therapies are mostly used in combination with other therapies [(CBT) or biological (drugs)]. It is, therefore, difficult to evaluate their effectiveness.

Behavioral interventions focus on the behavior but do not address the underlying cause of addiction, such as biological factors, cognitive bias, or social environment (i.e., the thing leading them to addictive behavior in the first place). A more holistic approach might be more effective in achieving lasting improvement.


Chesser, E. S. (1976). Behaviour therapy: Recent trends and current practice. The British Journal of Psychiatry, 129 (4), 289-307.

Davidson, W. S. (1974). Studies of aversive conditioning for alcoholics: A critical review of theory and research methodology. Psychological Bulletin, 81 (9), 571.

Elkins, R. L. (1991). An appraisal of chemical aversion (emetic therapy) approaches to alcoholism treatment. Behavior research and therapy, 29 (5), 387-413.

Hajek, P., Stead, L. F., West, R., Jarvis, M., Hartmann‐Boyce, J., & Lancaster, T. (2013). Relapse prevention interventions for smoking cessation. Cochrane database of systematic reviews, (8).

Streeton, C., & Whelan, G. (2001). Naltrexone, a relapse prevention maintenance treatment of alcohol dependence: a meta-analysis of randomized controlled trials. Alcohol and Alcoholism, 36 (6), 544-552.

Olivia Guy-Evans

BSc (Hons), Psychology, MSc, Psychology of Education

Associate Editor for Simply Psychology

Olivia Guy-Evans is a writer and associate editor for Simply Psychology. She has previously worked in healthcare and educational sectors.

Saul Mcleod, PhD

Educator, Researcher

BSc (Hons) Psychology, MRes, PhD, University of Manchester

Saul Mcleod, Ph.D., is a qualified psychology teacher with over 18 years experience of working in further and higher education.