What might red lines across my fingernails indicate?

Red lines on your fingernails can be a sign of several possible conditions. According to the provided references, these lines could be related to skin diseases or systemic conditions that affect your body. For example, horizontal red bands on nails might be linked to skin problems or infections.

Possible Causes:

1. Skin Conditions: Some skin diseases can cause changes in your nails, including red lines.
2. Infections: Certain infections, like those associated with COVID-19, can also lead to nail changes.
3. Systemic Health Issues: Changes in your overall health, such as nutritional deficiencies or other illnesses, might show up as changes in your nails.

If you notice red lines or other changes in your nails, it might be a good idea to talk to a healthcare provider to understand what might be causing them. They can help determine if it's something that needs further attention.