How long does it take for mehndi on the nails to fade away? Actually, it doesn't fade away, it stays there and only disappears while your nail grows; the colour moves further up until it disappears once you cut yer nails. So if somone has mehndi on their fingernails and want it removed as quick as possible in the natural way, they should try and get ill.. have the flu in particular. Ya see, I read somewhere that when one has the flu, one's hair and fingernails grow slightly faster than usual. Therefore, my advice to ppl who want their nails to be clear of mehndi would be to sleep without a blanket under the AC while its -300 degrees C outside, have cold showers and then hang out the washing in the cold while your hair's still wet. And share a glass of water with somone's who's ill. And voila! you'll have clear nails in no time!