Underdosing of phenothiazine antipsychot/neurolept, init

This code signifies a patient experiencing adverse effects or a worsening of their psychiatric condition due to receiving an insufficient dose of a phenothiazine antipsychotic or neuroleptic medication. This underdosing can lead to a lack of therapeutic effect, symptom exacerbation, or a return of previously controlled symptoms.

Apply this code when a patient presents with symptoms directly attributable to not receiving enough of their prescribed phenothiazine antipsychotic, such as a relapse of psychosis or uncontrolled agitation. This is appropriate for the initial presentation or admission related to the underdosing event.

• Always assign an additional code for the specific psychiatric condition being treated (e.g., F20.9 for schizophrenia).
• Ensure documentation clearly states that the patient received less than the therapeutic dose, rather than simply discontinuing the medication.
• The "A" in the 7th character indicates an initial encounter for the underdosing event.