Which of the following is a common adverse drug reaction to Atorvastatin?

Atorvastatin, as a statin medication used to manage cholesterol levels, is known to have myopathy as a significant adverse drug reaction. Myopathy refers to muscle weakness and pain, which can sometimes progress to a more severe condition known as rhabdomyolysis. This muscle-related toxicity is mainly due to the way atorvastatin works by inhibiting the HMG-CoA reductase enzyme, crucial in cholesterol synthesis, which may also impact muscle metabolism.

Patients on atorvastatin should be monitored for muscle symptoms, especially since myopathy can lead to elevated creatine kinase levels and potential complications if not addressed. While constipation, weight gain, and rash are possible side effects of various medications, they are not specifically associated with atorvastatin to the same extent as myopathy. This makes myopathy the most relevant answer regarding atorvastatin-related adverse reactions.