A patient who stopped using drugs is experiencing hallucinations, but toxicology tests are negative. What is the likely diagnosis?

• A. Schizophrenia
• B. LSD intoxication
• C. Delirium tremens
• D. Post-acute withdrawal syndrome

Answer: (B)

The scenario presents a patient who has stopped using drugs and is experiencing hallucinations, yet their toxicology tests return negative results. In this context, the most appropriate diagnosis is post-acute withdrawal syndrome.

Post-acute withdrawal syndrome (PAWS) occurs after a person has ceased substance use, especially from substances like alcohol or opioids, and may manifest in various psychological and physical symptoms. Hallucinations can be part of this syndrome, particularly as the brain begins to readjust to the absence of substances that have altered its normal functioning.

This condition is characterized by prolonged withdrawal symptoms following acute withdrawal, which may occur days to weeks after stopping the substance. Hallucinations are specifically linked to the neurochemical imbalances created by the abrupt cessation of substance use. Unlike other options where active intoxication or ongoing substance use would explain the symptoms, PAWS accounts for post-drug use conditions where symptoms persist even when no drugs are detected in the system.

Therefore, considering the timeline of stopping drug use and the absence of toxicological evidence, post-acute withdrawal syndrome is the most fitting diagnosis.