Hyperpigmentation after a fixed drug eruption

Inflammation from a fixed drug eruption can stimulate extra pigment in the affected skin. The result may be a brown, grey or dusky patch that remains after redness, swelling or soreness has improved. A defining feature is that a later reaction may appear in the same location after the triggering medicine is used again.

Darkening alone does not prove which medicine caused the eruption. A clinician will consider the timing of every medicine, the shape and location of the patch, and whether there was blistering, ulceration or mucosal involvement.

Do not deliberately reuse a suspected medicine to test the connection. Ask the prescriber to record the suspected reaction and advise on alternatives. Protect the patch from sunlight, avoid picking or friction, and use bland skin care while any active inflammation settles.

A topical corticosteroid may be prescribed for active inflammation, but it is not a universal treatment for a flat residual mark. Pigment-focused treatment should wait until the diagnosis is clear and the skin barrier is calm, because irritation can make the colour change more persistent.

Seek urgent care if the area blisters or peels, spreads quickly, becomes very painful, or affects the mouth, eyes or genitals. Facial swelling, wheezing, dizziness or breathing difficulty after a medicine requires immediate help. Arrange a review if the patch is changing, bleeding or not clearly linked to a previous eruption.

Is this residual pigment from a fixed drug eruption, or does it need another diagnosis? Which medicine should be avoided? Is a topical corticosteroid needed for active inflammation, and when is it safe to discuss treatment for the remaining colour?