Differential Diagnosis for Agitation Three Months After Stopping a Medication

• Single most likely diagnosis:
  • Discontinuation syndrome: This is a likely diagnosis given that the agitation started after stopping a medication, suggesting that the body has adapted to the presence of the medication and is now reacting to its absence. The specific medication is not mentioned, but many medications, especially antidepressants, antipsychotics, and benzodiazepines, can cause discontinuation syndromes that include agitation among their symptoms.
• Other Likely diagnoses:
  • Rebound anxiety or insomnia: If the medication was used to treat anxiety or insomnia, stopping it could lead to a rebound effect, where the symptoms return, potentially worse than before. Agitation could be a manifestation of severe anxiety or sleep deprivation.
  • Underlying psychiatric condition: The medication might have been masking an underlying psychiatric condition, such as bipolar disorder, which could present with agitation after the medication is stopped.
• Do Not Miss (ddxs that may not be likely, but would be deadly if missed.):
  • Serotonin syndrome: Although less likely if the medication was stopped three months prior, if the patient had been on an SSRI or another serotonergic agent and recently started another medication or supplement that increases serotonin levels, serotonin syndrome could occur. It's a medical emergency.
  • Akathisia: A side effect of antipsychotic medications, akathisia can persist or appear after the medication is discontinued and is characterized by subjective and objective restlessness.
• Rare diagnoses:
  • Tardive dyskinesia or dystonia: These are rare side effects of long-term use of antipsychotic medications. While they are more commonly associated with involuntary movements, in some cases, they could contribute to agitation due to discomfort or distress caused by the movements.
  • Withdrawal from other substances: If the patient was also using other substances (illicit drugs, alcohol) and stopped around the same time as the medication, withdrawal from these substances could lead to agitation.