The increasingly popular anticonvulsant and mood stabilizer Lamictal, used to treat epilepsy and bipolar disorder, contains a black box warning about life-threatening skin reactions, including Stevens Johnson syndrome and its more deadly form, Toxic Epidermal Necrolysis (TEN).

Lamictal, which in addition to receiving U.S. Food and Drug Administration (FDA) approval to treat epilepsy, seizures and Lennox-Gastaut syndrome (a severe form of epilepsy whose onset is typically before age 4), has also been approved since 2003 to treat Bipolar I disorder, characterized by severe mood episodes ranging from mania to depression.

While Lamictal is commonly associated with side effects such as dizziness, insomnia, nausea and vivid dreams, between 1968 and 2009 it was linked —  more than any other drug — to cases of Stevens Johnson Syndrome and Toxic Epidermal Necrolysis. A person taking Lamictal has a 14 times greater likelihood of getting one of those diseases, according to one study.

First FDA-approved in December 1994 for the treatment of partial seizures, Lamictal has gone on to receive approval for the treatment of a variety of other conditions. In epileptics, Lamictal treats focal seizures, primary and secondary tonic-clonic seizures. The drug was the first mood stabilizer approved by the FDA since Lithium some three decades earlier.

Of 200 reports of “severe cutaneous adverse reactions” (a category that encompasses scores of skin reactions) reported, 119 of them involved Lamictal. Eighty-six of those reports were linked directly to SJS and TEN.

The onset of Stevens Johnson Syndrome or Toxic Epidermal Necrolysis symptoms can occur immediately or take years to manifest. Most cases appear in the first two to eight weeks of therapy, or if the medication is suddenly stopped then resumed, but can take years to develop in adults who take Lamictal to treat bipolar disorder.

Stevens Johnson Syndrome is marked by flu-like symptoms that ultimately produce a potentially life-threatening skin disease manifested by a rash similar to a burn, open sores and skin peeling. Lamictal’s SJS symptoms have been reported as a purplish rash that spreads, painful blisters of the mucous membranes, blisters on the eyes, nose, mouth, and genitals, sloughing off of skin in large patches, joint and muscle pain and a burning sensation all over the body.

The FDA’s black box warning advises medical attention for any unexpected skin rash since it could be an indication of an SJS or TEN reaction.

Between 5 percent and 10 percent of patients will develop a rash, but only one in 1,000 patients will develop a serious rash. Rashes and other skin reactions are more common in children, so this medication is often reserved for adults.

Less serious Lamictal side effects include dizziness, drowsiness, headache, nausea, vomiting, constipation, diarrhea, blurred vision, indigestion, congestion, poor coordination, slurred speech, weight loss, insomnia, anxiety, confusion, depression, irritability, dry mouth, weakness, chest pain, rolling eye movements, infection, and abdominal pain.

Results of a study published in the journal Pediatrics showed that Lamictal posed an increased risk for TEN, which is diagnosed when the top layer of skin (the epidermis) detaches from the body, especially the mucous membranes, such as the mouth, eyes, and vagina.

Up to 40 percent of people who suffer TEN die from complications associated with the painful disease, compared with 5 to 15 percent of those with SJS. Survivors may experience lifelong health problems such as a secondary skin infection (cellulitis), sepsis (a blood infection), blindness, internal organ damage and permanent skin damage.