Only if that pill is an iron supplement. "The vitamin C in OJ can increase iron absorption, but components in some juices can interfere with how your body metabolizes certain medications," says Kathleen Besinque, associate professor of clinical pharmacy at the University of Southern California School of Pharmacy. The result: Your meds stay in your system too long (as when Zoloft is taken with grapefruit juice) or leave too quickly (as when taking Allegra with apple, orange or grapefruit juice), leading to dangerously high or low levels of the drug. "You shouldn't even have milk with your medication without asking the pharmacist first," Besinque says. "Drugs are usually tested with water, so if you are swallowing pills with other beverages, there's always the potential of unexpected interactions."