Erythema multiforme

Erythema multiforme is a skin reaction that can be triggered by an infection or medication. It's usually mild and goes away in a few weeks.

But there's also a rare, severe form that can affect the mouth, genitals and eyes and can be life-threatening. This is known as erythema multiforme major.

Erythema multiforme mainly affects adults under 40, although it can occur at any age.

Symptoms of erythema multiforme

Most people with erythema multiforme will just have a rash, but other symptoms can also sometimes occur.

Rash

The rash comes on suddenly and develops over a few days. It tends to start on the hands or feet, before spreading to the limbs, upper body and face.

The rash:

starts as small red spots, which may become raised patches a few centimetres in size
often has patches that look like a target or "bulls-eye", with a dark red centre that may have a blister or crust, surrounded by a pale pink ring and a darker outermost ring
may be slightly itchy or uncomfortable
usually fades over two to four weeks

In more severe cases, the patches may join together to form large, red areas that may be raw and painful.

Other symptoms

Additional symptoms of erythema multiforme can include:

a high temperature (fever) of 38C (100.4F) or more
a headache
feeling generally unwell
raw sores inside your mouth, making it hard to eat and drink
swollen lips covered in crusts
sores on the genitals, making it painful to pee
sore, red eyes
sensitivity to light and blurred vision
aching joints

These symptoms are more common in erythema multiforme major or a similar condition called Stevens-Johnson syndrome.

When to get medical advice

See your GP as soon as possible if you think you or your child may have erythema multiforme.

Your GP may be able to diagnose it just by looking at the rash, but they can refer you to a skin specialist (dermatologist) if they're not sure.

If erythema multiforme major or Stevens-Johnson syndrome is suspected, you'll be referred to hospital immediately because these conditions can be serious.

If you're unable to see a GP, contact your local out of hours service or NHS 111 for advice.

Causes of erythema multiforme

The cause of erythema multiforme is often unclear, but some cases are the result of a reaction to an infection or medication.

The condition can't be passed from person to person.

Infections

Most cases are caused by a viral infection – often the herpes simplex (cold sore) virus. This virus usually lies inactive in the body, but it can become reactivated from time to time.

Some people will get a cold sore a few days before the rash starts.

Erythema multiforme can also be triggered by mycoplasma bacteria, a type of bacteria that sometimes cause chest infections.

Medication

Medication can occasionally cause the more severe form of erythema multiforme. Possible medication triggers include:

antibiotics, such as sulfonamides, tetracyclines, amoxicillin and ampicillin
non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen
anticonvulsants (used to treat epilepsy), such as phenytoin and barbiturates

Treatments for erythema multiforme

Treatment aims to tackle the underlying cause of the condition, relieve your symptoms and stop your skin becoming infected.

Your doctor may recommend:

stopping any medication that may be triggering your symptoms – do not try this without speaking to your doctor first
antihistamines and moisturising cream to reduce itching
steroid cream to reduce redness and swelling (inflammation)
painkillers for any pain
antiviral tablets, if the cause is a viral infection
anaesthetic mouthwash to ease the discomfort of any mouth sores

More severe cases may be treated in hospital with:

stronger painkillers
wound dressings to stop your sores becoming infected
a softened or liquid diet if your mouth is badly affected – some people may need fluids given through a drip into a vein
steroid tablets to control the inflammation
antibiotics if you have or develop a bacterial infection
eye drops or ointment if your eyes are affected

Complications of erythema multiforme

Most people with erythema multiforme make a full recovery within a few weeks. There aren't usually any further problems and the skin normally heals without scarring.

But there is a risk the condition could come back at some point, especially if it was caused by the herpes simplex virus.

You may be given antiviral medication to prevent attacks if you experience them frequently.

In severe cases, possible complications can include: