This refers to the cluster of symptoms, both physical and psychological, that appear when someone abruptly stops or reduces the use of a substance they regularly consume. Common signs include stress, anxiety, depression, nausea, vomiting, muscle aches, and cramping.
These symptoms often drive individuals to resume substance use in an attempt to relieve the discomfort. Withdrawal syndrome can vary in intensity and duration depending on the substance, the dose, and the length of dependence.
Sources: SAMHSA_NCBI; ProjectKnow; UNODC