What could cause discoloration of my fingernails, and when should I see a doctor?

There are several reasons why your fingernails might change color. One common cause is a fungal infection, which may turn nails yellow, brown, or white. Certain medications, like minocycline, can lead to blue or gray nail discoloration. Sometimes, extra pigment builds up in the nail (a condition called melanonychia), which can cause dark streaks or overall dark nails. In older adults, nail changes may also occur naturally due to aging. It's a good idea to see a doctor when you notice sudden or unusual changes in your nail color, especially if they are accompanied by pain, changes in nail shape or thickness, or other symptoms like swelling. Before your appointment, you can use a free symptom checker to help identify potential causes and better prepare for your discussion with a healthcare provider. A medical professional can look at your nails, ask about other symptoms, and may perform tests to determine if these changes are harmless or if they signal a more serious condition. Getting an evaluation early helps ensure that if treatment is needed, such as for a fungal infection or for managing medication side effects, it can be started promptly.