Which of the following is a common symptom of substance withdrawal?

Severe mood swings are indeed a common symptom of substance withdrawal. When an individual who has been using a substance heavily and suddenly stops or reduces their intake, it can lead to significant emotional instability. This happens because the body has become accustomed to the effects of the substance, and withdrawal disrupts the brain's chemistry and emotional regulation. As a result, individuals may experience rapid and intense changes in mood, ranging from irritability and anxiety to sadness and agitation, which are indicative of the body's struggle to regain balance after the absence of the substance.

In contrast, while symptoms such as low appetite can accompany withdrawal, they are not as directly related to the psychological aspects of the process. Increased energy and heightened senses, on the other hand, may not typically coincide with withdrawal; instead, on a variety of substances, withdrawal would more commonly make individuals feel sluggish or unstable rather than energized. These distinctions help clarify why severe mood swings are a hallmark feature of withdrawal symptoms.