How to Avoid the Disease That Burns Your Skin From the Inside Out

A year ago, 32-year-old Melissa Mok wasn't feeling well. She developed flu-like symptoms that quickly escalated into mysterious blisters that covered her entire body, head to toe, inside and out. Puzzled, Melissa's doctors placed her into quarantine while trying to figure out what was overtaking her otherwise healthy body.

It took several days, but Melissa was eventually diagnosed with Stevens-Johnson syndrome, an early stage of toxic epidermal necrolysis syndrome (TENS). Melissa was transferred to Sunnybrook, where she spent time in the intensive care unit and burn centre, unable to walk for weeks because of the blisters on her feet.

One out of five people will die from TENS, and four out of five people will suffer the rest of their lives from having had it

Sunnybrook's head of dermatology, Dr. Neil Shear, describes TENS as a horrible, painful and life-threatening disease that literally causes a patients' skin to burn off their body from the inside out. While rare (there are about 20 cases in Ontario every year), Dr. Shear says the effects are devastating: one out of five people will die from it, and four out of five people will suffer the rest of their lives from having had it.

So what could cause this horrible disease? Dr. Shear says they are able to determine the cause in about seven out of 10 people, and he says it's usually one of a few well-known drugs that can trigger the problem. Those drugs include allopurinol, often prescribed for gout, and carbamazepine, used for pain disorders and epilepsy. Dr. Shear says these are important drugs and help many people, but for some, they can cause TENS. And that's where a simple blood test can make all the difference.

Dr. Shear says this genetic blood test has been available for some time. The problem is, few patients know about it and it's not widely discussed. Patients need to pay for it (he says it's under $200), but knowing the possible alternative, he says it's money well spent.

If you've been on these drugs for some time, Dr. Shear says a test isn't necessary as most cases of TENS appear in the first month of treatment.

About 70 per cent of TENS cases are triggered by a few well-known drugs

So who needs the blood test? Dr. Shear says anyone newly prescribed allopurinol. And for carbamazepine, that includes anyone with origins from Southeast Asia.

These medications aren't the only cause of TENS, and Melissa still isn't sure what triggered her symptoms. But having survived TENS -- and still recovering from its aftermath -- she is a firm supporter of people being aware.

"It's not just the heartache but it's also all the time spent in the hospital," she says. "The possibility of what could have happened is scary to think about." She'll continue her care at Sunnybrook, now a leading centre in the treatment for TENS. And for anyone who will listen, she says to ask about the blood test. She's living proof that even though side effects are rare, they can still happen.