Muscular side effects of various anesthetics, analgetics, antibiotics, 
antihistaminic drugs, antiretrovirals, cardiotropics, immunosuppressants, 
lipid-lowering drugs, psychotropic drugs, anticancer drugs, and other substances 
are more frequent than assumed and are easily overlooked. Clinically, muscular 
side effects manifest as fatigue, myalgias, persistent or transient weakness, 
stiffness, intolerance to exercise, psychomotor slowing, muscle cramps, wasting, 
dyspnea, dysphagia, fasciculations, reduced tendon reflexes, impaired 
consciousness, myoglobinuria, renal failure, or hyperthermia. Diagnosis of these 
drug-induced myopathies is based on history, clinical neurologic examination, 
blood work, urine analysis, repetitive stimulation, electromyography, and muscle 
biopsy. A drug which induces muscular side effects should never be given again. 
Particularly in patients suffering from primary myopathy, myotoxic drugs should 
be applied with caution. The drugs which most frequently induce muscular side 
effects are steroids, statins, fibrates, antiretrovirals, immunosuppressants, 
colchicine, amiodarone, and anticancer drugs. Many drugs exhibit their myotoxic 
potential only in combination with other drugs or premorbid pathologic myogenic 
conditions.