Can intramuscular (systemic) cortisone injections help fighting alopecia areata?

I have alopecia areata which has been growing since one year. I have a little hair growing at the site of dermal injections only. My doctor suggested intramuscular cortisone injections (4 periodical). Previously, I had cortisone injections for alopecia and sinisitius. It was fine with no side effects. Why every doctor tell me different opinion about cortisone ?. I used many corticosteroids creams prescribed by my doctor which didn't show any benefits. However, I am currently using (Elidel).