Adrenaline injectors (EpiPen®, Anapen®) are injected into the thigh muscle. There is no evidence that injecting the second dose of adrenaline into the same thigh muscle as the first dose is a problem. The most important thing is to follow the ASCIA Action Plan and give another dose of adrenaline after 5 minutes if there is no response.
The adrenaline nasal spray, neffy®, is sprayed into the nostril. If a second dose is needed after 5 minutes, it is better to spray into the same nostril as absorption will be better. If, however, you spray the second dose into the other nostril, neffy® will still work.