(CNN) The US Food and Drug Administration warned on Thursday that the benefits of fluoroquinolone antibiotics do not outweigh the risks -- which include aortic aneurysm -- for certain patients, according to the latest research. The research is based on reports of patient problems and on studies published between 2015 and 2018.

Fluoroquinolone antibiotics are often used to treat serious respiratory infections, pneumonia, urinary tract infection, and even plague and exposure to anthrax. They include drugs sold under the names ciprofloxacin (Cipro), gemifloxacin (Factive), levofloxacin (Levaquin), moxifloxacin (Avelox), norfloxacin (Noroxin) and ofloxacin (Floxin).

Patients take them orally or through injection.

The drugs may cause aortic aneurysm , a bulge in an artery that can grow and burst, causing dangerous or fatal bleeding.

Patients most at risk for an aortic aneurysm after taking these antibiotics are the elderly, those with high blood pressure, people who have a history of blockages of the aorta or other blood vessels, and those who have genetic conditions like Marfan syndrome or Ehlers-Danlos syndrome