I have had mctd since 2005 and had an extreme case which did not respond to steroids. IVIG tamed my immune system and I took prednisone and imuran for many years after that. Today, I am off all controlling meds.
There are many other possible treatments for mctd but prednisone is usually the first that is tried because it usually works, is fast acting and inexpensive. Docs will put you on some other prednisone sparing drug like imuran or methotrexate. Several others have already been mentioned and there are others. Any of these treatments have potential side effects but the operative word is "potential." Not everyone has terrible side effects with a given drug but some do. The most important things to focus on is not to worry about side effects which might not happen but to get your disease diagnosed and under control as quickly as possible. The sooner you can control your immune system the better the outcome you can expect. If a given treatment causes serious side effects then you can stop it and shift to another treatment or combination of treatments.
Mctd is a disease with endless variation in presentation, severity, response to treatment so no one, not even your doctors can tell you anything with accuracy. Most of the people on this forum with mctd have mild cases compared to the potential of the disease. Also, some with mctd have different diseases than the tradtional description of sle lupus, scleroderma and polymyositis.
MCTD (SLE Lupus, polymyositis, scleroderma). Diagnosed 2005. Kidney, liver, GI tract, dysphagia, raynauds, barretts esophagus, quadriplegic in 2005. Recovered and now active in downhill skiing, golf, hiking. Meds: amlodipine, benezapril, omeprazole, potassium, folic acid, vitamins, maxide.
Remain Optimistic and you can overcome.