Reverse tolerance

Reverse tolerance or drug sensitization is the phenomenon of a reversal of the side-effects from a drug, the reduction of insensitivity caused after drug tolerance has been established, or, in some cases, an increase in specific effects of a single drug existing alongside a tolerance to other effects of the same substance. Typically this involves the use of additional medication or abstinence from a drug for a period of time, known as a drug holiday. Such drugs include amphetamines and SSRIs.

As a result, regular users commonly experience a quick decrease of unwanted side effects, without an equivalent loss of its stimulant properties.