Common side effects associated with using Lescol XL are: Stomach upset, Headache, Abdominal pain, Diarrhoea, Muscle pain, Fatigue, Insomnia, Nausea, Sinusitis, Bronchitis, Urinary tract infection (UTI), Elevated liver enzymes Rash, Back pain, Arthralgia, Myopathy, Rhabdomyolysis, Rupture of tendon, Pharyngitis, Rhinitis, Cough, Constipation, Pancreatitis, Dizziness Constipation, Diarrhoea, Fatigue, Gas, Heartburn, Headache, Insomnia, Joint pains Abdominal pain or cramps, Blurred vision, Dizziness, Easy bruising or bleeding, Itching, Muscle pain or cramps, Rash, Yellowing of the skin or eyes