Which symptom is indicative of hallucinogen withdrawal?

Muscle twitching can be indicative of hallucinogen withdrawal, particularly when substances like LSD or psilocybin are involved. While hallucinogens are not typically associated with severe withdrawal symptoms compared to substances like opioids or alcohol, some users may experience physical symptoms such as muscle twitching or tremors as their body readjusts after discontinuing use.

This physiological response can occur as the central nervous system attempts to recalibrate after the absence of the substance that had previously altered its functioning. The presence of muscle twitching underscores the body's adaptation process, reflecting potential neurochemical disturbances that can happen after the cessation of hallucinogenic substances.

In contrast, other symptoms mentioned, such as euphoria, severe hallucinations, and cardiac irregularities, are not typical of withdrawal but rather reflect the active effects or nature of hallucinogens during use. Euphoria would be a desired effect while under the influence, severe hallucinations indicate the drug's primary effects, and cardiac irregularities could occur from acute intoxication rather than withdrawal.