Hello, I will ask you a few questions regarding your disease. You haven t mentioned why are you taking sazo. Usually the diseases for which sazo is needed also lead to backache (A part of disease). Regarding side effects, I think best part is that you have been tolerant to the drug for last few months. You need to be vigilant for developing white blood deficiency, folic acid deficiency or some damage to your liver enzymes. (Very rare effects in very few patients). You need to take folic avoid along this drug, liver function testing after every 3 to 6 months and a blood complete picture once every 1 to 3 months. There are many other non serious side effects which are present in almost all other drugs like a stomach acidity problem due to prolonged use. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Muhammad Faisal Bacha, Internal Medicine Specialist