The Growth elixir was a concoction made by Phineas and Ferb to make Baljeet's watermelon grow bigger but Candace used it to make herself taller, which backfired on her and made her 50 feet tall. Phineas mentioned that only works once, but he used again to make their Aqua Primates grow. ("Attack of the 50 Foot Sister", "Phineas and Ferb Hawaiian Vacation")