The funnyman was discharged from hospital last Wednesday (21Mar12) after receiving treatment for a heart attack which struck just moments before a stand up gig in Dallas, Texas.
He was thought to have fully recovered, but he suffered another cardiac event on Sunday (25Mar12) and is now resting in an Arizona hospital.
His spokeswoman tells E! News, "He had another minor heart attack today, but is resting well in a Sedona hospital... He is with family doing OK. Gallagher doesn't like people telling him what to do, but he just needs to rest. We're just praying he'll listen."