An automatic injection device for delivering a dose from a medicine containing syringe and comprising: a housing for containing the syringe; a force applicator for applying a force to eject medicine from the syringe; a trigger coupled to the force applicator for releasing the force applicator to cause an injection; a boot covering a needle attached to the syringe to protect and maintain sterility of the needle; a first mechanical interlock for preventing actuation of the trigger prior to removal of the boot and for allowing actuation or commencement of an actuation sequence following removal of the boot; and a second mechanical interlock (1305,1307) for detecting pressure applied to the device by the user's skin following removal of the boot, and configured to prevent actuation of the trigger in the absence of pressure and to allow actuation when sufficient pressure is detected, wherein the trigger is attached to the housing and is arranged to release the force applicator when the trigger is moved axially in a proximal direction relative to the housing, the automatic injection device further comprising an outer casing, wherein the housing is located within the outer casing, and is axially moveable within the outer casing, wherein the second mechanical interlock is provided by a biasing device acting between the outer casing and the housing, wherein the biasing device is arranged to bias the housing in a proximal direction relative to the outer casing and thereby tend to push a proximal end of the housing through a proximal end of the casing, such that the trigger is held within the outer casing, thereby restricting access to the trigger, and wherein the proximal end of the housing is arranged to be pressed against the user's skin to move the housing in a distal direction relative to the outer casing such that the trigger projects from the distal end of the outer casing and becomes accessible. a housing for containing the syringe; a force applicator for applying a force to eject medicine from the syringe; a trigger coupled to the force applicator for releasing the force applicator to cause an injection; a boot covering a needle attached to the syringe to protect and maintain sterility of the needle; a first mechanical interlock for preventing actuation of the trigger prior to removal of the boot and for allowing actuation or commencement of an actuation sequence following removal of the boot; and a second mechanical interlock (1305,1307) for detecting pressure applied to the device by the user's skin following removal of the boot, and configured to prevent actuation of the trigger in the absence of pressure and to allow actuation when sufficient pressure is detected, wherein the trigger is attached to the housing and is arranged to release the force applicator when the trigger is moved axially in a proximal direction relative to the housing, the automatic injection device further comprising an outer casing, wherein the housing is located within the outer casing, and is axially moveable within the outer casing, wherein the second mechanical interlock is provided by a biasing device acting between the outer casing and the housing, wherein the biasing device is arranged to bias the housing in a proximal direction relative to the outer casing and thereby tend to push a proximal end of the housing through a proximal end of the casing, such that the trigger is held within the outer casing, thereby restricting access to the trigger, and wherein the proximal end of the housing is arranged to be pressed against the user's skin to move the housing in a distal direction relative to the outer casing such that the trigger projects from the distal end of the outer casing and becomes accessible. wherein the biasing device is arranged to bias the housing in a proximal direction relative to the outer casing and thereby tend to push a proximal end of the housing through a proximal end of the casing, such that the trigger is held within the outer casing, thereby restricting access to the trigger, and wherein the proximal end of the housing is arranged to be pressed against the user's skin to move the housing in a distal direction relative to the outer casing such that the trigger projects from the distal end of the outer casing and becomes accessible.