16 Feb 2012
By: NG WAN CHING
Every year, more than 100 people here suffer from a painful and severe skin condition which is a serious allergic reaction to certain types of medication.
Some may even end up dying.
Last month, an 18-year-old polytechnic student tragically became the first casualty this year of Stevens-Johnson syndrome (SJS).
It is believed he developed the rare and serious skin disease after taking acne medication.
The adverse reaction causes skin cells to die and the skin to blister badly on mucosal surfaces around the face and genitalia.
In rare cases, SJS leads to toxic epidermal necrolysis, in which large pieces of the skin die and fall away, leaving the person vulnerable to life-threatening infections.
Certain drugs tend to cause SJS, including some kinds of antibiotics, anti-epileptic drugs (carbamazepine and phenytoin) and allopurinol (for gout), said Dr Bernard Thong, head and senior consultant at the department of rheumatology allergy and immunology at Tan Tock Seng Hospital.
Though such an adverse reaction cannot be predicted, the risk of getting SJS is fortunately very low and the risk of death, even lower.
In the last two years, the Health Sciences Authority recorded 213 cases of adverse drug reactions which led to SJS and toxic epidermal necrolysis.
The risk of death from SJS is estimated to be about 10 per cent and toxic epidermal necrolysis about 30 per cent.
Patients with medical conditions, such as HIV infections or active or recent cancers, tend to have a higher risk of developing SJS, said Dr Thong, but even young healthy individuals can fall prey to it.
The reaction may be associated with fever, abnormal blood cell counts and abnormal liver function tests.
Sometimes, the cause of the condition is unknown but, in many cases, the drug has been taken continually for a period of at least seven to 10 days before it causes a reaction.
However, it is very unlikely that someone would develop a reaction to a medication that they have tolerated for a long time, said Dr Lee Haur Yueh, associate consultant dermatologist at Singapore General Hospital.
And while it can occur in children and young people, the syndrome is far more common in the elderly, who tend to take a lot more medication, said Dr Lee.
Cases can also range from mild to severe, said Dr Derrick Aw, senior consultant at the University Dermatology Clinic at National University Hospital.
Patients with a mild case of SJS would usually have a small, itchy rash.
In severe cases, the rash is more extensive and there is also some tenderness.
In the most serious cases, there are painful ulcers or blisters on the mucosal surfaces, such as the lips, eyes, oral cavity, anal margin and external genitalia.
The worst occurs when SJS overlaps with or evolves into the closely related toxic epidermal necrolysis, in which up to 30 per cent of the epidermis (the outer layer of the skin) dies and falls away.
This is exceedingly painful and also exposes the patient to infection, as the protective skin layer is gone.
Indeed, most deaths occur from infections.
Therefore, it is vital that SJS is diagnosed early and the culprit drug identified and stopped, said Dr Aw.
Most patients with SJS are admitted to hospital, where they can be closely watched in case their conditions progress to dangerous levels.
Patients with very severe symptoms are treated in the hospital’s Burns Unit (see facing page).
Treatment usually aims to provide relief from the pain, as well as to make sure the patient is adequately hydrated and fed, by feeding tube, if necessary, said Dr Aw.
A short course of steroids may be given especially if the cause is suspected to be an adverse drug reaction, he added. Steroids suppress the immune system, which caused the overreaction to the drug.
Email: wanching@sph.com.sg
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