The risk of nerve damage that fluoroquinolone antibiotics carry may come on rapidly and perhaps be permanent, the FDA warned Thursday.
The agency said it is requiring an update to the drug labels and medication guides for all systemic fluoroquinolones in order to clarify the risk of peripheral neuropathy associated with the medications.
Peripheral neuropathy -- with symptoms in arms and legs such as pain, burning, tingling, numbness, or weakness -- is a known risk of the drug class and warnings to that effect were added to drug labels in 2004.
But a recent review of data from the Adverse Event Reporting System (AERS) database found that reports of peripheral neuropathy continue to come in despite the warnings.
The reason, the agency said in a , appears to be that "the potential rapid onset and risk of permanence were not adequately described."
Approved fluoroquinolone drugs include levofloxacin (Levaquin), ciprofloxacin (Cipro), moxifloxacin (Avelox), norfloxacin (Noroxin), ofloxacin (Floxin), and gemifloxacin (Factive).
The fluoroquinolones have previously been associated with other rare but severe adverse events, .
And the updated warning on peripheral neuropathy comes just a day after researchers in Taiwan described the risk of blood sugar swings in diabetics taking members of the class.
The risk of peripheral neuropathy occurs only with fluoroquinolones that are taken by mouth or by injection, the agency said; the topical formulations of the drugs "are not known to cause this risk."
The FDA urged doctors to switch patients to a nonfluoroquinolone if symptoms of peripheral neuropathy develop, unless the benefit of continued treatment outweighs the risk.
Peripheral neuropathy can occur any time during treatment with fluoroquinolones and can last for months to years after the drug is stopped, the agency said.
In some cases, the FDA added, it can be permanent.
In 2011, the agency reported, about 23.1 million patients had a prescription filled for an oral fluoroquinolone from retail pharmacies. In hospitals about 3.8 million patients were billed for an injectable fluoroquinolone.