While the Flash is easily one of the most powerful heroes in the DC Universe, his abilities do have a number of side effects that could prove detrimental to the Scarlet Speedster, including one horrifying weakness that was actually revealed by Marvel Comics.
Wally West aka the Flash is able to pull off astounding feats of heroism because of his connection to a cosmic power grid known as the Speed Force. By channeling the Speed Force, the Flash can sprint through the time stream, heal incredibly fast, and even separate his molecules to phase through objects at will. There are a few catches to these powers, however, including his heightened susceptibility to drowning as every tiny bit of water he could accidentally breathe in while swimming would fill his lungs in seconds due to his relative speed/breathing rate. While that side effect to super speed does pose a significant danger–especially if Flash ever wanted to help out Aquaman on a mission– Marvel pointed out another cost to his powers that would assuredly kill the Flash in a matter of months.
Related: Marvel's Version of Flashpoint Came Way Before DC's, & Was Much Darker
In Uncanny X-Men #527 by Matt Fraction, Whilce Portacio, and Leonard Kirk, Marvel Comics introduces a mutant named Gabriel Cohuelo aka Velocidad. Like the Flash, Velocidad is a speedster whose body is greatly impacted every time he uses his powers. Velocidad’s powers allow him to slow down time while he remains unaffected, effectively giving him super speed, though his body ages at a relativistic rate during this process. This means that he could age months in a matter of moments if he strenuously uses his powers.
Based on the fact that the Flash’s metabolism and body functions speed up because of
Read more on screenrant.com