Cleveland Clinic research links horizontal lines on your fingernails to high fever, severe illness, or major stress weeks earlier. The surprise of new horizontal lines on your fingernails can make you panic about recent health events you thought were behind you.
The next type of lines on your fingernails goes even deeper.
3. 
Deep Grooves or Multiple Lines on Your Fingernails
A office worker named Maria watched multiple deep grooves and cracks form on several nails at once. These lines on your fingernails often mean the body went through a tough period of nutritional shortage or ongoing stress.
Mayo Clinic notes that protein deficiency or digestive issues can leave visible deep lines on your fingernails. The constant reminder of lines on your fingernails every time you type or cook can drain your confidence and make simple tasks feel frustrating.
Color changes with lines on your fingernails raise more red flags.
4. 
Lines on Your Fingernails with Color Changes
A nurse named Anna spotted dark brown streaks running down one nail. When lines on your fingernails come with color shifts, they need closer attention.
