Retinoic acid creams may be effective in some patients with neck darkness, depending mainly on the cause. Retinoids have a role in regulating melanin metabolism and may have some decolourisation effect on neck darkness that occurs due to some skin conditions (e.g. melanosis). However, if the darkening of the neck is due to other causes, such as primary hypoadrenocorticism, the application of retinoic acid creams is usually ineffective.