No, the Medusa's Blood is compatible with all special coats. You won't lose the 5th Element.

The 5th Element (and Vintage Apple) has a different coat design for each species, so you will see the wings if you apply the Medusa's Blood after the coat.

You won't lose your coat if you apply the Medusa's Blood after a Golden Apple, Medallion, etc. other special coat items, but you won't see the wings because those coats do not have a separate design for each species. You'll just get the bonus from the Medusa's Blood.

Thank you (: