What causes exogenous ochronosis?

The condition is an uncommon pigmentary reaction in skin exposed to hydroquinone, a lightening ingredient. It may appear as blue-grey, slate, or brown-black patches, often where a product has been applied repeatedly. The colour can look speckled or net-like, and the skin may feel thicker or develop small raised bumps. It can be mistaken for melasma or post-inflammatory pigmentation, but the treatment approach differs. Product strength, frequency, duration, skin sensitivity, and unregulated formulations may influence risk. Darkening after irritation does not prove ochronosis, so diagnosis should be made by a clinician rather than by colour alone.

Stop using a suspected lightening product and bring its container, ingredient list, or a photograph of the label to a dermatology appointment. Avoid switching to another bleaching cream, scrubbing the area, or layering acids and retinoids over irritated skin. Use gentle cleansing, moisturiser, and daily broad-spectrum sun protection while awaiting advice. Read about [Hydroquinone](/materials/hydroquinone/) to understand why ingredient history matters. A dermatologist may discuss examination, photographs, and carefully selected treatment options.

Arrange assessment if darkening persists after stopping the product, spreads beyond the application area, becomes textured, itchy, sore, or inflamed, or causes significant distress. Seek prompt advice for blistering, swelling, severe burning, or an eye-area reaction. Early review can also help exclude another pigment disorder and prevent further irritation from self-treatment.

Could this be exogenous ochronosis or another pigment condition? Does the product contain hydroquinone or related ingredients? Should I stop every active product? Would testing or a biopsy help? Which treatment is least likely to worsen irritation or pigmentation?