The eminent Muslim scholar and renowned Da`iyah, Sheikh `Abdel Khaliq Hasan Ash-Shareef, states:

If a lady has a legal Shar`i excuse to perform tayammum (dry ablution) due a disease she is suffering from, then she is permitted to use nail polish. This is on condition that she displays the nail polish only in the presence of her husband, mahrams or other women in whose presence she is permitted to display her feet.”