Drug phototoxic response

This code signifies an adverse skin reaction, such as a rash or sunburn-like appearance, that occurs when a patient is exposed to sunlight or other UV radiation after taking a specific medication. It represents a non-allergic, dose-dependent reaction where the drug absorbs UV light and causes damage to skin cells.

Use this code when documentation clearly states a patient developed a phototoxic reaction due to a prescribed or over-the-counter medication. This typically involves symptoms like exaggerated sunburn, blistering, or hyperpigmentation appearing in sun-exposed areas after drug ingestion. Documentation should specify the drug involved and the causal link to UV exposure.

• Distinguish from photoallergic reactions (T49.x with L56.1), which are immune-mediated and can occur with very small drug doses.
• Always sequence the drug causing the adverse effect (T36-T50) as a secondary diagnosis.
• Ensure documentation specifies "phototoxic" rather than a general "photosensitivity" to accurately apply this code.