After being sued by the advocacy group Public Citizen, the Food and Drugs Administration agency has requested makers of antibiotics of a certain class to add ‘black box’ label warnings for these products, since studies have shown that they increase the risk of patients to suffer a tendon rupture.

The products that are requested to show this type of labeling are ciprofloxacin, which is produced by Bayer under the name of Cipro, Ciproxin and Ciprobay, and levofloxacin, a drug produced by Ortho McNeil and sold under the name of Levaquin. Both products are part of the class called fluoroquinolone antibiotics.

Studies have shown that fluoroquinolone antibiotics increase the risk of a person suffering a tendon rupture three times. The risk is even bigger for persons over the age of 60, or which have suffered heart, lungs or kidney transplant operations. Patients that undergo a steroid treatment and that are simultaneously administered this type of antibiotics also present an increased risk.

Most tendon ruptures involve the Achilles tendon, which connects the calf muscle to the heel, but ruptures of tendons located in the shoulders, hands, biceps and thumbs have also been encountered.

People realize they experience a tendon rupture when they hear a popping or snapping sound accompanied by an acute pain in the area where the tendon is located. While most of the times the tendon that is about to snap hurts people up to two weeks before the actual lesion happens, in some cases this takes place without any previous symptoms.

People who take the medication and feel pain in their tendons are advised to stop taking the drug, stop any exercise and request help from a doctor.