Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis

This is a rare but life-threatening reaction in which the skin peels away and the mucous membranes — mouth, eyes and genitals — break down. A medicine causes it almost every time. Stevens-Johnson syndrome and toxic epidermal necrolysis are not two different illnesses but one, divided by how much surface is involved: the more skin comes off, the more severe it is and the more often it is called necrolysis. It is treated only in hospital, often in intensive care or a burns unit. There is no option here of waiting until morning or taking an antihistamine: if it is suspected, you call an ambulance and stop the suspected medicine at once.

How it begins

The deceptive thing about this condition is that the rash is not what arrives first. One to three days beforehand comes something easily taken for flu:

• high temperature, chills, exhaustion, aching all over;
• a sore throat that makes swallowing difficult;
• stinging, burning or a gritty feeling in the eyes, discomfort in bright light;
• cough, headache, muscle and joint pain.

On its own this means nothing. But if it turns up in someone who started a new medicine in the past few weeks, it needs watching closely, and the first sign on the skin or in the mouth calls for action without delay.

What shows on the skin and the mucous membranes

The rash usually starts on the face and trunk and spreads within hours to a day. It does not look like allergic hives and it behaves differently:

• the patches are dark red, purplish or greyish, often with a darker centre, and run together in places;
• the skin hurts and burns rather than itching — one of the key distinctions;
• flaccid blisters appear, break, and the skin comes away in sheets, leaving a weeping surface like a burn;
• the skin slides and lifts even where there is no rash yet, if you run a finger across it.

What identifies the condition, though, is the mucous membranes — involved in nearly everyone, and often before the skin:

• mouth and lips: painful ulcers, bloody crusts on the lips, no eating, no drinking and no swallowing even of saliva;
• eyes: redness, swollen lids, purulent discharge, severe pain and an unbearable intolerance of light;
• genitals and the area around the anus: ulcers and sharp pain on passing urine;
• sometimes pain behind the breastbone on swallowing and a hoarse voice, when the throat and voice box are involved.

The combination of a painful rash plus mouth ulcers and red eyes plus fever is precisely the picture worth remembering this whole page for.

What to do right now

Call an ambulance (in Europe, the single number 112) or take the person straight to hospital if even this much is present:

• a painful rash with blisters or peeling skin, particularly after starting a new medicine;
• ulcers in the mouth or on the lips together with a rash or a temperature;
• red, painful eyes with light intolerance alongside a rash or fever;
• a rash with fever in someone who began a new drug within the past month;
• difficulty breathing or swallowing, swelling of the tongue, lips or face. That is a different reaction — anaphylaxis — but the response is the same: an ambulance immediately.

Stop the suspected medicine at once, without waiting for a doctor. It is the one thing a person can do for themselves, and it changes the outcome: the sooner the drug is withdrawn, the smaller the area affected. If several medicines are involved, do not sit and work out which one is guilty — simply do not take the next dose, and tell the doctor everything that was being taken.

What else matters in those hours:

• bring every packet along, including over-the-counter medicines, supplements and herbal remedies, or photograph them;
• do not put ointments or creams on the skin just in case, and do not burst the blisters;
• antihistamines, paracetamol and home remedies do nothing here and only cost time;
• do not drive in this state, and do not send the person on their own.

What sets it off

In the great majority of cases the cause is a medicine taken over the past few weeks. The reaction does not usually begin with the first tablet but somewhere between the fourth day and the fourth week after starting; if that drug has caused it once before, everything unfolds faster.

The classes most often linked to it are:

• anticonvulsants, which are prescribed for epilepsy, for pain and in psychiatry alike;
• sulfonamide antibiotics and drugs related to them;
• allopurinol, used for gout;
• certain other antibiotics, including the penicillins and the group used in tuberculosis and HIV infection;
• non-steroidal anti-inflammatory painkillers, especially the long-acting ones.

This does not make those medicines dangerous or something to avoid: the reaction is extremely rare, a handful of cases per million people a year, and the drugs listed are needed and effective. The list serves a different purpose — to know that when the signs described appear, the first thing checked is the link with a recently started treatment.

In children the same picture is set off more often by an infection than by a medicine, chiefly mycoplasma pneumonia and, less commonly, herpes simplex. The risk is also higher in people whose immune system is weakened, and in anyone who has had this before or has a close relative who has: inherited susceptibility counts here.

What happens in hospital

Treatment is supportive, which does not mean second best: when a large area of skin is involved the body loses fluid and heat exactly as it does with a burn, and it is good nursing care that decides the outcome. In hospital the following is done:

• the culprit drug is withdrawn, along with everything else that can be spared;
• fluids and nutrition are replaced, often by tube, because swallowing is impossible;
• the skin is dressed with non-adherent dressings, as for burns;
• pain is treated properly — it is severe here and there is no need to endure it;
• infection is watched for;
• the eyes are examined daily to stop the lids adhering to the eyeball, and an ophthalmologist takes that on.

Whether systemic treatment to damp down the reaction itself is also needed is decided case by case: there is as yet no single agreed standard.

The outlook depends on how much skin is involved and how fast the drug was stopped. With limited involvement most people recover; in the most severe form a substantial proportion of patients die. The skin heals in two or three weeks, but getting your strength back takes months.

What it can be mistaken for

An ordinary drug rash is many times more common and carries no danger: it is pink, it itches, the mucous membranes are clear, the person feels reasonably well, and there is no fever or only a slight one. Those four features are what tell them apart, and in doubtful cases it is a doctor who looks, not the internet.

Chickenpox and hand, foot and mouth disease also produce blisters and mouth ulcers, but neither brings severe pain in the skin, sheets of peeling, or a gravely ill patient. Erythema multiforme stands slightly apart — a related but far milder reaction, often triggered by herpes.

Where there is doubt, it is settled by examination rather than by watching at home. An error in that direction is expensive: time here is measured in hours.

After discharge: what stays for good

The main thing a person takes home from hospital is a prohibition. The medicine that caused the reaction, and drugs chemically close to it, must never be taken again: a second episode tends to be worse than the first.

• Get a discharge summary with the exact name of the drug, and ask the doctor to list what else must be avoided.
• Carry that information on you — a card in your wallet or a bracelet, not only a note on your phone. Ambulance crews and emergency departments look where it is written down, and if you are seriously ill you may not be able to tell them.
• Name this reaction to every doctor, dentist, anaesthetist and pharmacist, and do not let it be recorded as "intolerance" or "allergy" without qualification: the difference is that a test dose here is out of the question in principle.
• Warn your blood relatives: their risk of the same reaction to the same drug is above average.

The second thing, rarely mentioned in advance: the eyes suffer for longer than the skin does. Dryness, light intolerance, grittiness, scarring of the lids and conjunctiva, clouding of the cornea and loss of vision can develop months after recovery. Ophthalmology follow-up has to continue after discharge, not only while you are on the ward. Marks and scars on the skin, altered nails and a dry mouth can also remain, and after genital involvement, scarred narrowing that is dealt with by a gynaecologist or a urologist. And almost everyone is left for a long while with fatigue and a fear of medicines; that is to be expected, and it is worth raising with a doctor rather than managing alone.

Online consultation

Stevens-Johnson syndrome itself is neither treated nor confirmed remotely: the signs described mean an ambulance. But an online appointment has two sensible uses. The first is before anything goes wrong: working out whether a rash that appeared while taking a new medicine really is harmless or means hospital immediately, and what to do about the treatment itself. The second is after recovery: putting together a clear list of what you must not take, setting it down so that it will be seen in an emergency, finding replacements for the drugs you need, and deciding which specialists to see and how often — the ophthalmologist first of all.

This material is for information only and does not replace medical advice.