The following serious side effects need to be reported to your local doctor as soon as possible if they are exhibited during treatment with Valsartan: abnormal weight gain, numbness, chest pain, rapid or heavy heartbeats, the feeling that one might faint, fevers, discolored urine, nausea, vomiting, or pronounced muscle pain or tenderness. The drug may also be responsible for the following minor side effects: flu symptoms, back pain, diarrhea, dry mouth, constipation, abdominal pain, itching, loss of appetite, insomnia, dizziness, fatigue, impotence, or headaches. If side effects are ignored, they could lead to the eventual breakdown of a patient's skeletal muscle tissue.