Pharmacological criteria are the final grouping (Criteria 10 and 11). Tolerance (Crite- rion 10) is signaled by requiring a markedly increased dose of the substance to achieve the desired effect or a markedly reduced effect when the usual dose is consumed. The degree to which tolerance develops varies greatly across different individuals as well as across substances and may involve a variety of central nervous system effects. For example, tol- erance to respiratory depression and tolerance to sedating and motor coordination may develop at different rates, depending on the substance. Tolerance may be difficult to de- termine by history alone, and laboratory tests may be helpful (e.g., high blood levels of the substance coupled with little evidence of intoxication suggest that tolerance is likely). Tol— erance must also be distinguished from individual variability in the initial sensitivity to the effects of particular substances. For example, some first-time alcohol drinkers show very little evidence of intoxication with three or four drinks, whereas others of similar weight and drinking histories have slurred speech and incoordination.
Withdrawal (Criterion 11) is a syndrome that occurs when blood or tissue concentra— tions of a substance decline in an individual who had maintained prolonged heavy use of the substance. After developing withdrawal symptoms, the individual is likely to con- sume the substance to relieve the symptoms. Withdrawal symptoms vary greatly across the classes of substances, and separate criteria sets for withdrawal are provided for the drug classes. Marked and generally easily measured physiological signs of withdrawal are common With alcohol, opioids, and sedatives, hypnotics, and anxiolytics. Withdrawal signs and symptoms with stimulants (amphetamines and cocaine), as well as tobacco and cannabis, are often present but may be less apparent. Significant withdrawal has not been documented in humans after repeated use of phencyclidine, other hallucinogens, and in- halants; therefore, this criterion is not included 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 withdrawal is associated with a more severe clinical course (i.e., an earlier onset of a substance use 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., opioid 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 erroneous diagnosis of ”addiction” even when these were the only symptoms present. Individuals whose only symptoms are those that occur as a result of medical treatment (i.e., tolerance and withdrawal as part of medical care when the medications are taken as prescribed) should not receive a diagnosis solely on the basis of these symptoms. However, prescription medications can be used inappropriately, and a substance use disorder can be correctly diagnosed when there are other symptoms of compulsive, drug-seeking behavior.
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- ity, a mild substance use disorder is suggested by the presence of two to three symptoms, moderate by four to five symptoms, and severe by six or more symptoms. Changing severity across time is also reﬂected by reductions or increases in the frequency and/ or close of substance use, as assessed by the individual’s own report, report of knowledgeable others, clinician’s observations, and biological testing. The following course specifiers and descrip- tive features specifiers are also available for substance use disorders: “in early remission,” ”in sustained remission," "on maintenance therapy,” and ”in a controlled environment.”
Definitions of each are provided within respective criteria sets.