Underdosing of antiviral drugs, subsequent encounter

This code indicates that a patient is experiencing the effects of receiving too little of an antiviral medication, or not taking enough as prescribed, during a follow-up visit. This underdosing is causing a current health issue or complication that requires ongoing medical attention.

Use this code when a patient presents for a subsequent encounter related to an adverse effect or complication stemming from insufficient antiviral drug administration. This could include a patient whose viral infection is worsening or not resolving due to previously inadequate antiviral therapy. It's appropriate for follow-up care after the initial underdosing event.

• Always assign an additional code for the specific adverse effect or complication resulting from the underdosing.
• Ensure the "D" seventh character is appropriate for a subsequent encounter, indicating ongoing care for the underdosing effect.
• Distinguish from poisoning (T36-T65 with 5th or 6th character 1-4) which implies an adverse effect of a correctly prescribed and administered drug.