Side-effects of steroid injections are very unlikely but occasionally people notice a flare-up of pain in the injected area within the first 24 hours after the injection. This usually settles on its own within a couple of days but taking simple painkillers like paracetamol will help. Evidence-based professional reference pages https://search.grainger.illinois.edu/searchaidlog3/sourcelognew.asp?ID=782151&goog--https://tr.wikipedia.org/wiki/Vitamin