Fluoroquinolones, which include Cipro, can cause aortic and mitral regurgitation, where the blood backflows into the heart. The risk is greatest in the first 30 days of taking the drug.
The problem could affect up to 10 per cent of people taking the antibiotics, say researchers at the University of British Columbia. They discovered 12,505 cases of valvular regurgitation among 125,020 people taking the antibiotic and compared them to others taking different antibiotics.
The risk was greatest within the first 30 days, and then started to decline over the following 30 days.
Doctors like to prescribe fluoroquinolones because they are broad-spectrum pills that are easily absorbed. But, says researcher Mahyar Etminan, the drugs are convenient, but not essential, especially for community infections. "The inappropriate prescribing may cause both antibiotic resistance as well as serious heart problems," he said.