A phase pulse infection was a potentially fatal condition, the result of being shot with a phase-modulated energy weapon set to a high level. Andorians were particularly susceptible to phase pulse infections.
In 2154, Lieutenant Talas, a member of the Andorian Imperial Guard under the command of Commander Shran, died of a phase pulse infection, a result of being shot with a phase-pistol by a Tellarite named Naarg. Although Talas was only grazed, the pistol was set to kill, injuring her beyond Doctor Phlox's ability to treat. (ENT: "Babel One", "United")