Brittle nails are often caused when the nails dry out. They are surprisingly porous and are almost one-fifth water and even a slight change in moisture content can cause problems. Fortunately, prevention and treatment are simple and straightforward.
Applying a base coat before painting your nails can be a good idea, as is wearing shoes that allow you to wiggle your toes. Keeping brittle nails trimmed can reduce how much damage they suffer. Use proper toenail scissors or clippers, taking care to cut straight across and not down into each corner. The best time to do this is after a bath or shower when your nails are soft.