Gallagher was admitted to London's King's College Hospital in March 1995, and it was only then that the extent of his ill health became apparent; his liver was failing and the doctors determined that, in spite of his young age, a liver transplant was the only possible course of action. After thirteen weeks in intensive care, while waiting to be transferred to a convalescent home, his health suddenly worsened when he contracted a staphylococcal (MRSA) infection, and he died on 14 June 1995, at the age of 47. He was unmarried and had no children.