There are many things that can cause your nails to become brittle and lose their strength. However, it can be a symptom of dermatological diseases, such as psoriasis, or even systemic diseases, such as kidney disease. However, if your nails become weak and brittle, it can be a sign of ageing, lack of vitamins or even frequent use of chemical products. In these cases, there are different treatments to restore the strength of your nails.