Med Injector

30 on Standard (Modern), 29 on Standard (Classic) and 28 on Insanity. Leon starts with 1. Grace's first is on the Nurses' Station floor, in the pool of blood to the south-west (ch02). Other fixed ones: the Sterilization Chamber and Monitor Control Room safes (ch14). Leon's Supply Box sells it as "Injection".

Fully restores your health. Works for both Grace and Leon.

Green Herb + 60 Infected Blood, or Mixed Herb (G+G) + 30 Infected Blood (Grace only)

Grace unlocks the recipe with the Blood Specimen (Converged) (ch03). With herbs to spare, the (G+G) + 30 version saves blood; with blood to spare, a Green Herb + 60 saves herbs. One source asks 40 blood with the (G+G); 3 say 30. Leon cannot craft it: he buys it for 1,500 credits and sells it for the same. On Insanity the ones dropped by a Conference Room zombie and a Connecting Corridor zombie (ch03) are gone. Using one breaks Never Touch the Stuff.