Does green nail syndrome cause discoloured nails?

Green nail syndrome is associated with bacterial growth in a space beneath or beside a nail, especially when the nail is lifted or repeatedly exposed to moisture. The colour may look green, yellow-green or darker as the nail changes. One affected nail can be more suggestive of local separation or moisture exposure, while several altered nails may point to another process. A clinician may examine the nail, surrounding skin and any debris before deciding what is causing the change.

Keep the nail clean and dry, trim only loose or overhanging nail carefully, and avoid covering it with polish or an artificial nail while it is being assessed. Do not scrape beneath the nail or use household disinfectants. Reduce prolonged soaking and wear protective gloves for wet work. If the nail is lifted, tender or has an odour, arrange an assessment so infection, injury or another nail disorder can be considered.

Seek medical advice if the colour spreads, the nail becomes painful, swollen or drains fluid, or the surrounding skin turns red. Prompt review is sensible when several nails change suddenly, the nail is dark after an injury, or you have diabetes or reduced immunity. A clinician should assess a dark streak, bleeding or a changing mark rather than assuming it is green nail syndrome.

Ask whether the nail is lifted, whether moisture or trauma may be contributing, and whether a sample or targeted treatment is needed. Ask how to protect the nail while it grows out and which changes should prompt a follow-up visit.