Clobazam (Onfi) Can Cause Serious Skin Reactions, FDA Warns

December 03, 2013

The antiseizure drug clobazam (Onfi, Lundbeck) can trigger rare but potentially fatal skin reactions, the US Food and Drug Administration (FDA) announced today.

The agency approved clobazam, a benzodiazepine, in 2011 as an add-on therapy to treat seizures that accompany a severe form of epilepsy called Lennox-Gastaut syndrome. The FDA said other benzodiazepines generally are not associated with serious skin reactions.

For clobazam, the skin reactions to watch for are Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN). Patients taking clobazam can experience these disorders at any time, but the risk goes up during the first 8 weeks of treatment or when treatment resumes after it was stopped. All the cases of these 2 adverse events identified by the FDA landed patients in the hospital, with 1 patient going blind and another dying.

The FDA advises clinicians to closely monitor patients taking clobazam for SJS and TEN, especially at the start of therapy or when the drug is reintroduced. Signs and symptoms include rashes, blistered or peeling skin, mouth sores, and hives. Clobazam should be halted at the first appearance of a rash, and if other signs and symptoms point to a serious skin reaction, the therapy should not be resumed.

Clinicians also should instruct patients taking clobazam to seek medical care immediately if they spot a rash or some other sign of hypersensitivity, according to the FDA. However, patients should not stop taking clobazam without first consulting their healthcare provider, because suddenly halting treatment on their own can trigger serious withdrawal problems such as persistent seizures, nervousness, and hallucinations.

More information on today's announcement is available on the FDA Web site.

To report problems with clobazam, contact MedWatch, the FDA's safety information and adverse event reporting program, by telephone at 1-800-FDA-1088; by fax at 1-800-FDA-0178; online at; with postage-paid FDA form 3500, available at; or by mail to MedWatch, 5600 Fishers Lane, Rockville, Maryland 20852-9787.


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