Drinking plenty of fluids during the heat of summer is especially important for people taking medications, since the effects of medication can become more pronounced with dehydration.

"The combination of depleted fluid volume and medication can lead to problems such as dangerously low blood pressure, particularly for older patients who are sensitive to becoming dehydrated," said Dr. David Calhoun, University of Alabama at Birmingham (UAB) cardiologist and UAB Hypertension Clinic director. "People taking diuretics are particularly vulnerable to dehydration."

Calhoun recommends at least 48 ounces of water daily, and more than that when spending time out in the sun or when exercising.