The FDA formally approved new warnings Thursday for a powerful class of antibiotics known as fluoroquinolones.

The move comes after numerous investigations into reports of serious complications and even deaths related to the fluoroquinolone Levaquin (levofloxacin).

The new warnings say fluoroquinolones should not be used for patients with acute bacterial sinusitis, acute exacerbation of chronic bronchitis or uncomplicated urinary tract infections unless all other treatment options have been exhausted.

“Fluoroquinolones have risks and benefits that should be considered very carefully,” said Edward Cox, M.D., director of the Office of Antimicrobial Products in the FDA’s Center for Drug Evaluation and Research. “It’s important that both health care providers and patients are aware of both the risks and benefits of fluoroquinolones and make an informed decision about their use.”

The FDA announced its intent to add new warnings to the antibiotics in May. Fluoroquinolones already come with warnings of an increased risk of tendinitis and tendon rupture, worsening symptoms for those with myasthenia gravis and the potential for irreversible nerve damage.