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Rare But Possibly Deadly Skin Reactions Linked to Onfi Use

Rare skin reactions that can result in permanent harm or death can be a side effect of using the anti-seizure drug Onfi (clobazam), the Food and Drug Administration (FDA) is warning. Changes to the Onfi drug label and the patient Medication Guide to describe the risk of these serious skin reactions have been approved by the FDA.

These Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) skin reactions may happen any time during Onfi treatment. The chances of these reactions increase in the first eight weeks of treatment or when use of the drug is stopped and then re-started. All the cases of SJS and TEN in the FDA case series resulted in hospitalization.

One person was blinded and another died due to the condition.

Onfi is a benzodiazepine medication used with other medications to treat seizures associated with a severe form of epilepsy called Lennox-Gastaut Syndrome.

Patients using Onfi need close monitoring, according to the FDA

The FDA recommends patients be closely monitored for signs or symptoms of SJS/TEN, especially during initial treatment or when re-introducing therapy. Health care professionals are advised to discontinue use of the drug and consider alternative treatments at the first sign of a skin rash, unless it is clearly not drug-related.

Patients showing symptoms of SJS or TEN must be careful and discuss their situation with their treating physician. Those taking Onfi should get immediate medical treatment if they develop a rash, blistering or peeling of the skin, sores in the mouth or hives. However, they should not stop taking the drug without first talking to their health care professionals. Ceasing Onfi suddenly also carries risks of serious health problems, including seizures that will not stop, hallucinations, shaking, nervousness and stomach or muscle cramps.

The FDA encourages healthcare professionals and patients to report adverse events or side effects related to the use of Onfi to the FDA’s MedWatch Safety Information and Adverse Event Reporting Program.  A form is available online ( or can be obtained by calling the FDA at 800-332-1088.

No cure for Lennox-Gastaut Syndrome, but medications offer hope

There is usually no single medication that will control Lennox-Gastaut Syndrome seizures, according to the National Institute of Neurological Disorders and Stroke. Children with the syndrome who improve initially may later show tolerance to a drug or have uncontrollable seizures.  There is no cure for the disorder. Complete recovery, including freedom from seizures and normal development, is very unusual.

Lennox-Gastaut Syndrome seizures usually begin before four years of age. Seizure types vary among patients and include tonic (stiffening of the body, upward deviation of the eyes, dilation of the pupils and altered respiratory patterns), atonic (brief loss of muscle tone and consciousness, causing abrupt falls), atypical absence (staring spells) and myoclonic (sudden muscle jerks).

There may be periods of frequent seizures mixed with brief, relatively seizure-free periods.

Most children with Lennox-Gastaut Syndrome experience some degree of impaired intellectual functioning or information processing, along with developmental delays and behavioral disturbances. Lennox-Gastaut syndrome can be caused by brain malformations, perinatal asphyxia, severe head injury, central nervous system infection and inherited degenerative or metabolic conditions.