A heating device (1) is described for a container (7) of a liquid pharmaceutical product having a viscosity of 50-500 cP at 4° C. and contained within a glass container. The device (1) comprises a substantially rigid, thin-walled housing (2) defining an openable chamber for receiving the container (7), a heat source (6) in the chamber comprising a hermetically sealed package containing a super-cooled metal salt fluid or liquid and an actuator (14) for activating the super-cooled metal salt to produce heat, wherein the ratio of the volume of the metal salt to the intended volume of the product is no more than 1:1.
