Do the effects of hypothyroidism include black nails?
Black nails are not normally caused by hypothyroidism. However, medications (like Cytoxan) can cause this to happen. Also, certain other medical conditions, like fungal infections of the nail, can do this. Injuries to the nail itself can make your nails turn black. If you are really concerned, you can see a dermatologist to find out what is going on with your nails.