Hello and thank you for using HCM for your question. SoluMedrol 40 mg can be given IM with no adverse side effects, as long as it is reconstituted correctly and administered properly. There are several factors that must be considered before injecting it into the Deltoid muscle though, rather than into a larger muscle.It is often best to give any IM injections into a large muscle like the gluteus maximus, but if the deltoid is well developed, a 1 cc solution of Solu Medrol could be given in the deltoid without any atrophy or other problem. It is usually safer to give IM medications, especially if over 1 cc into the gluteus maximus (a buttock muscle)because this muscle tends to be used by individuals frequently (thus has good circulation) and is one of the larger muscles in the body. Solu Medrol (as well as any IM injection) should not be given into an already atrophied muscle, or a small muscle, or a muscle that was the site of a previous infection. Since you were given only a steroid injection, you should not have any long term effects and the pain will die down soon enough. Injections of other substances like pain killers or antibiotics can cause lasting pain.THANK YOU.