signs and symptoms with stimulants (amphetamines and cocaine), as well as tobacco and
cannabis, are often present but may be le ss apparent. Significant withdrawal has not been
documented in humans after repeated use of  phencyclidine, other hallucinogens, and in-
halants; therefore, this criterion is not incl uded for these substances. Neither tolerance nor
withdrawal is necessary for a diagnosis of a substance use disorder. However, for most
classes of substances, a past history of withdraw al is associated with a more severe clinical
course (i.e., an earlier onset of a substance us e disorder, higher levels of substance intake,
and a greater number of substance-related problems).
Symptoms of tolerance and withdrawal occurring during appropriate medical treat-
ment with prescribed medications (e.g., opio id analgesics, sedatives, stimulants) are spe-
cifically not counted when diagnosing a substance use disorder. The appearance of normal,
expected pharmacological  tolerance and withdrawal during the course of medical treat-
ment has been known to lead to an erroneou s diagnosis of “addiction” even when these
were the only symptoms pr esent. Indivi duals whose only symptoms are those that occur
as a result of medical treatment (i.e., tolera nce and withdrawal as part of medical care
when the medications are taken as prescribed) sh ould not receive a diagnosis solely on the
basis of these symptoms. However, prescripti on medications can be used inappropriately,
and a substance use disorder can be correc tly diagnosed when there are other symptoms
of compulsive, drug-seeking behavior.
Severity and Specifiers
Substance use disorders occur in a broad range of severity, from mild  to severe, with se-
verity based on the number of symptom criteria endorsed. As a general estimate of sever-