What is the BEST indicator of physical dependence on alcohol or another drug?

The presence of withdrawal symptoms is the best indicator of physical dependence on alcohol or another drug because these symptoms arise when the body has adapted to the presence of the substance and has become reliant on it to function normally. When someone who is physically dependent suddenly reduces or stops intake, their body reacts negatively to the absence of the drug, leading to withdrawal symptoms that can range from mild (such as anxiety and irritability) to severe (such as seizures or delirium tremens in the case of alcohol).

Withdrawal symptoms demonstrate that the central nervous system, as well as other bodily systems, have undergone physiological changes due to regular use of the substance. The severity and type of withdrawal symptoms can vary depending on the substance, the duration of use, and individual factors, but their presence unmistakably signals a physical dependence that has developed. This factor stands apart from psychological cravings, appetite changes, or loss of control over usage, which, while relevant to substance use disorders, do not inherently indicate physical dependence.