Underdosing of antitussives, initial encounter

This code signifies a patient's adverse reaction or complication arising from taking less than the prescribed or recommended dose of an antitussive medication. This underdosing results in the intended therapeutic effect not being achieved, leading to persistent or worsening cough symptoms.

Apply this code when a patient presents with ongoing or exacerbated cough due to insufficient intake of a cough suppressant. This typically occurs when a patient misunderstands dosing instructions, forgets doses, or intentionally takes less medication than prescribed.

• Requires a seventh character for the encounter (A, D, or S). 'A' is for initial encounter.
• Use an additional code to identify the specific antitussive drug if known (e.g., from categories T36-T50).
• Consider a Z91.1xx code if the underdosing is due to patient noncompliance with medication regimen.