The drugs are ACE inhibitors - commonly prescribed for high blood pressure, heart failure, plus kidney failure in diabetics.
While they are lifesavers, Dr. James Roberts, the director of emergency medicine at Mercy Philadelphia Hospital says about once a week, he sees a bizarre side effect.
"All of a sudden, and for no good reason, they begin to have swelling of the tongues and lips and throat, and it can progress, and it can go away and come back," says Dr. Roberts.
Dr. Roberts says sometimes, it blocks a patient's airway and they need a tube down the throat to breathe.
The condition is called angioedema, which develops when fluid floods into tissue.
Dr. Roberts says there's no drug to stop the reaction.
"It stops by itself, or in the severe cases, you have to find an airway for the patient, to help them breathe," he says.
In his 40 years of experience, he says he's had 4 deaths.
Overall, it happens in about 1 per cent of those taking ACE inhibitors, but in about 5% of African American patients.
Dr.Roberts says doctors have asked for a "black box" warning on the drugs, however, the food & drug administration refused.
So he wants people taking ACE inhibitors to be on the lookout for it.
"It can kind of come and go for a couple of days. Some people think they have an insect bite on their lip, because it got swollen. Or they think it's a food allergy. They take Benadryl, and it goes away. It would have gone away anyway. But they;re convinced, so they stay on the medicine," he says.
