Like Dr. Mario, Luigi in his doctor persona makes use of megavitamins to defeat Viruses. In a similar fashion to Dr. Mario, Dr. Luigi will toss megavitamins that the player has to control in order to eliminate the Viruses.
It has been suggested that Dr. Luigi has a more laid-back personality than his brother, as in the introduction cutscene to Dr. Luigi, he is seen walking slowly with a tired look on his face. After he sees the Viruses however, he becomes shocked, and prepares megavitamins for use, now looking worried.
Dr. Luigi appears again in Dr. Mario: Miracle Cure, where he uses the same gameplay as in Dr. Luigi's "Operation L" mode. This marks the first appearance of Dr. Luigi on a handheld. Also, he is not seen with his hat, but instead with a head mirror, just like his brother.