Be sure to monitor your blood sugar levels on a regular basis.Changes in body electrolytes (chemicals that are important for the cells in your body to function, such as sodium and potassium) and body fluids can occur with metoprolol/HCTZ. Tell your doctor if you develop dry mouth, thirst, weakness, tiredness, drowsiness, restlessness, muscle pains or cramps, muscle tiredness, dizziness or fainting