American drug safety officials issued their most urgent warning on a popular class of antibiotics, saying that using drugs like Cipro may lead to ruptured tendons and tendonitis.

The U.S. Food and Drug Administration ordered makers of fluroquinoline drugs -- a potent class of antibacterials -- to add a prominent "black box" risk warning to their products, which include Cipro, Floxin and Levaquin.

Tendons are the tissues that connect muscles to joints, such as the Achilles tendon in your heel.

Usually, tendon ruptures are thought of as sports injuries, generally occurring among men in their mid-30s.

But it was antibiotics that led to injuries that can include a snap or a pop in the tendon area, bruising after an injury, or inability to move the affected area or bear weight.

Scientists don't fully understand the link, but FDA officials said that many of the serious injuries appear to be preventable if patients stop taking the drug at the first sign of pain or swelling in a tendon, call their doctor, and switch to another antibiotic.

Gardasil Vaccine Warning

More than 7,800 people who took an STD vaccine have reported adverse effects in the past two years.

Many complainants linked taking Gardasil to nausea, paralysis, and even death, according to the Centre for Disease Control.

The CDC is investigating the reports of illness, and the vaccine's manufacturer Merck and Co. Inc. said it was looking into the adverse reactions.

Gardasil is designed to prevent the spread of human papilloma virus. Certain strains of HPV can cause cervical cancer in girls and women.

What should parents do -- should they allow their child to get the vaccine?

First, we need to say that linking an unexpected event to the shot doesn't yet mean the shot caused it -- it could be a coincidence. It seems that no deaths are related to the shot but definitely more investigations are needed.

Many parents in my practice are now asking me if their daughter should get this shot during the upcoming school year. My answer is: you don't necessarily have to give them the shot -- it's an individualized situation. You can only get HPV if you're having sex, so you need to talk with your child and assess the situation.

If you anticipate that your 11 or 14-year-old may become sexually active in the next few years, then they should have the shot.

With a report from CTV British Columbia's Dr. Rhonda Low