What are the aims of this leaflet?

This leaflet has been written to help you understand more about erythema multiforme. It tells you what it is, what causes it, what can be done about it, and where you can find out more about it.

What is erythema multiforme?

The term ‘erythema’ is a redness of the skin, often because of inflammation or increased blood flow to the affected area. It is a common symptom for many inflammatory skin conditions, among others. The term ‘multiforme’ means in multiple forms.

Erythema multiforme (EM) is a hypersensitivity reaction (when the immune system mistakenly identifies a harmless substance as harmful) which tends to develop suddenly. Usually, it will disappear on its own, but sometimes treatment may be required. It can occur in any age group but is seen mainly in young adults. EM is slightly more common in men.

EM often starts with the development of multiple red spots on the affected area. The spots usually begin on the feet and hands and spread upwards towards the trunk. The face is often affected. Over time, these spots change to plaques (raised patches) that look like targets (concentric circles). They have a dusky red (dark red) centre, a paler area surrounding it, and a dark red ring around the edge. Because of this, they are called ‘target lesions’. Sometimes, the centre of the target can be crusted or blistered. Sometimes the centre of the target can be crusted or blistered.

EM is usually mild - 'erythema multiforme minor' – with only the skin affected and clearing up in days to weeks. If it's worse we call it, 'erythema multiforme major', which has similar skin features to EM minor, but additionally there is involvement of one or more mucosal membranes (e.g. the lips, the inside of the mouth, the windpipe, the oesophagus (food pipe), the anus or genital area, and the eyes) and usually some associated symptoms, such as fever or joint pain.

What causes erythema multiforme?

The cause of EM is not fully understood. It is thought to be a skin reaction which occurs following a trigger. It is thought that around 9 in 10 cases are triggered by infections such as the herpes simplex virus (the cold sore virus) or mycoplasma bacteria which can cause lung infection.

Medications (tablets/drugs) can be a trigger of EM. Drugs which can cause EM include non-steroidal anti-inflammatory drugs (given for joint and muscle pain, for example, ibuprofen or aspirin), antibiotics and anticonvulsants (used to treat epilepsy or nerve pain) as well as statins, immunotherapy drugs, and vaccinations.

Is erythema multiforme hereditary?

No.

What are the symptoms of erythema multiforme?

If EM is mild, you may feel perfectly well, and your rash may not cause any symptoms or it may cause a mild itch or burning sensation.

If your EM is more severe (EM major), you may have a fever and a headache, and feel unwell for a few days before the rash appears. Blisters on your skin may burst and leave painful areas. If your eyes are affected, you may become sensitive to light and notice blurring of your vision. Raw areas inside the mouth can make it hard to eat and drink. Genital soreness can make passing urine painful.

What does erythema multiforme look like?

In erythema multiforme minor: 

• The spots usually develop over the course of 3 - 4 days, starting on the hands and feet, and then spreading up the limbs to the trunk and face.
• At first the spots are small, round, slightly raised red areas, some of which turn into the ‘circular lesions’ described above. Small blisters form in the centre of some of the circles.
• The rash usually fades over 2 - 4 weeks.
• People usually recover fully from this type of erythema multiforme.
• Recurrences are common in some individuals, especially where herpes simplex virus (cold sores) is the cause.

In erythema multiforme major: 

• You may feel ill and have a high temperature.
• The spots are usually larger and run into each other. ‘Circular lesions’ can usually still be seen.
• Large blisters may form, and then burst to leave red oozing areas.
• Your lips may be covered with crusts, large raw areas may appear inside your mouth, and your eyes may swell up and turn red.
• Complications are rare and are mainly from scars left after the EM has healed on the skin, in the mouth or the eyes.

How is erythema multiforme diagnosed?

There are no specific tests for EM. The diagnosis is usually made by looking at the skin and a story of recent exposure to one of the possible causes mentioned above. Occasionally it is necessary to do a skin biopsy (to remove a small sample of skin under a local anaesthetic) to confirm the diagnosis under the microscope and exclude other possibilities. Sometimes, EM may be caused by viruses like herpes simplex virus (HSV). To test for this virus, a swab from your mouth or a blood test might be taken.

Can erythema multiforme be cured?

Most patients with EM recover completely; however, there can be a risk of further attacks, particularly following cold sores.

How can erythema multiforme be treated? 

Your doctor will look for known causes for the skin condition. If a particular medication is suspected, it should be stopped straight away. If an infectious cause is found, it should be treated.

The treatment will then depend on the severity and symptoms of the EM:

• Mild rashes will clear up in a few weeks spontaneously. Moisturisers and topical corticosteroids can be prescribed to speed up recovery and reduce symptoms of itch or burn.
• Severe rashes: Patients may need to be nursed in hospital as the skin may need regular dressings, pain relief and fluid and salt replacement. Antibiotics may be needed if the damaged skin is infected. An eye specialist may be needed if the eyes are affected. Oral steroids are sometimes given, especially in the early stages. Other immunosuppressant medications may also be used in cases that are difficult to treat.
• Recurrent attacks may be a problem. If they always follow a cold sore and come up several times a year, then it may be worth taking a small twice daily dose of a drug called aciclovir which is designed to suppress the herpes simplex virus (the virus responsible for cold sores) for several months.
• Secondary bacterial infections may occur in the site of rash, which can be treated with appropriate antibiotics.
• Scarring around mouth may cause restriction to mouth movements. To prevent this, if the rash involves the mouth, regular mouth opening exercises can be beneficial.

Self-care (What can you do?)

• If you have had one attack of EM, remember there is a risk that you will have another.
• If a medication was suspected to be the cause, it is vital that this is avoided in the future.
• If your attacks follow cold sores, you may want to ask your doctor about taking antiviral tablets long-term.
• Sun exposure can trigger herpes simplex virus (cold sore). To reduce the risk of reactivation it is advised to regularly apply sunscreen. This helps shield your skin from the sun, which can decrease the number of flare-ups. 

Where can I get more information about erythema multiforme?

Web links to other relevant sources:

www.nhs.uk/conditions/erythema-multiforme/

www.dermnetnz.org/reactions/erythema-multiforme.html

Jargon Buster: www.skinhealthinfo.org.uk/support-resources/jargon-buster/

Please note that the British Association of Dermatologists (BAD) provides web links to additional resources to help people access a range of information about their treatment or skin condition. The views expressed in these external resources may not be shared by the BAD or its members. The BAD has no control of and does not endorse the content of external links.

This leaflet aims to provide accurate information about the subject and is a consensus of the views held by representatives of the British Association of Dermatologists: individual patient circumstances may differ, which might alter both the advice and course of therapy given to you by your doctor. 

This leaflet has been assessed for readability by the British Association of Dermatologists’ Patient Information Lay Review Panel 

BRITISH ASSOCIATION OF DERMATOLOGISTS PATIENT INFORMATION LEAFLET

PRODUCED | AUGUST 2004

UPDATED | FEBRUARY 2010, APRIL 2013, JUNE 2016, JANUARY 2020, JULY 2024

NEXT REVIEW DATE | JULY 2027