Chemical cosh is a term used primarily by the British. To cosh someone means to bang them on the head, resulting in the person being sedated or knocked unconscious. A chemical cosh, then, refers to sedating people with chemicals, or medications. The term is generally used to refer to the situation where sedation is unnecessary, but it has also been used to describe the effects of Ritalin, or other similar drugs, prescribed to children diagnosed with Attention Deficit Disorder (ADD) or Attention Deficit Hyperactivity Disorder (ADHD).

Most frequently, the term chemical cosh is used to refer to overmedicating the elderly, and in some cases prisoners, with strong antipsychotics. Some studies have been conducted to research this problem as it relates to the older dementia patients who take medications like haloperidol, risperidone and thioridazine. The results suggest that these medications may be prescribed not so much for the purpose of treating the dementia, but rather to serve as a tranquilizer — to calm or sedate the patients. The trouble with this practice, according to research released in 2007, is that many antipsychotic drugs have exceptionally heavy side effects, including a doubling of the risk for stroke in the elderly.

Another study, conducted over a three-year period by Professor Clive Ballard, uncovered some realities that caused great concern in both the medical community and the population at large. To some, the results of the study showed that a chemical cosh was practiced to intentionally shorten the lives of people with dementia. Those who defend the practice of prescribing antipsychotics to dementia patients argue that these medications are only prescribed when absolutely necessary — in order to help patients who cannot be controlled by other means. Ballard’s study on chemical cosh in the elderly raised questions about the long term use of these medications even for those who may truly need them. Some argue that the prescription of these drugs is akin to a long-term form of euthanasia.

Other studies show that some countries routinely sedate their prisoners with chemical cosh drugs. Especially because of the potential side effects of chemical cosh drugs, some critics consider this practice as a form of torture and adamantly argue that these practices cease.

Referring to Ritalin or other ADD medications as chemical cosh drugs is usually done in the pejorative. Such statements are generally made to express the attitude that this is a practice of drugging otherwise healthy children into sedate behavior just because they don't behave like "most other kids." There are certainly arguments for and against the use of ADD and ADHD medications and some medical experts concede that these medications may be overused in some areas, perhaps as a chemical cosh, and underutilized in others.