A patient who develops muscle weakness shortly after starting to take simvastatin is experiencing what type of medication-related problem?

Muscle weakness or cramping is a common side effect of "-statin" medications used to treat high cholesterol. The question does not provide sufficient detail to identify whether a drug-drug interaction or therapeutic contraindication could be contributing to the patient's symptoms. If the patient were allergic to simvastatin, an immune response resulting in swelling, hives, or fever would be more likely to occur.