It is believed that steroid injections are likely to be most beneficial within the first month of developing a patch of alopecia areata. It may also be that by controlling inflammation early on, the immune system is quietened down and may not cause patches of hair loss elsewhere in the scalp though this has not been conclusively proven. Steroid injection can however be given at any stage, as recommended by your doctor, even one or two years after a patch has been present.