Taking crestor (rosuvastatin) 4 about 3 years now, no side affects, now all of the sudden i feel muscle pain and tenderness can side affects start after years of use?

They can.: Muscle injury syndromes secondary to lipid lowering medications can occur at any time during therapy although 2/3 of the cases occur in the first 6 months. The best course of action would be to notify the prescribing physician and be evaluated as soon as possible. The treatment of these syndromes is obviously to discontinue the medication.

Unfortunately, Yes: Unfortunately, with statin drugs muscle pain and tenderness can occur at anytime. There are options that can be taken if this occurs. A, you could stop taking the medication for a couple of mouths, then restart it to see if the side effect returns. B, you could lower the dose of the statin and see if that resolves it. Or c, you could switch to another statin drug. Of course, ask your doctor first.