Does melanonychia cause discoloured nails?

Melanonychia describes extra melanin pigment in the nail, often seen as a brown, grey, or black band running from the base toward the tip. It may affect one nail or several. The colour can come from pigment-producing cells becoming more active, and it can also follow injury, inflammation, medicines, or other conditions. A band that widens, becomes irregular, shows several shades, or extends onto nearby skin deserves particular attention.

Remove nail polish and take a well-lit photograph showing the whole nail and its base. Note whether the mark moves outward as the nail grows, whether it began after trauma, and whether the nail is lifting, splitting, or painful. Arrange a dermatology assessment for a new unexplained band, a band limited to one nail, or a mark that is changing. Do not file away the pigment or rely on home creams to identify its cause.

Seek timely review if pigment becomes broader or uneven, the border looks irregular, several colours appear, or pigment reaches the skin beside the nail. Prompt care is also sensible for swelling, pus, marked tenderness, or a nail that separates. Sudden severe pain after an injury may need immediate assessment even when pigment is not the main concern.

Ask whether the pattern suggests pigment, infection, trauma, or another cause; whether dermoscopy is useful; and whether monitoring or a sample is needed. Ask how to photograph the nail and what change should trigger an earlier review.