What causes dark nipples?

[News]

A person's nipples can change color at different times in their life. There are many different reasons why this might happen, most of which are harmless, hormone-related, and linked to pregnancy or menstruation. This article explains more about these causes of dark nipples, plus when someone might need to see a doctor.

More... (https://www.medicalnewstoday.com/articles/321383.php)