Erythema Multiforme

Erythema multiforme is a sudden skin reaction, often triggered by infections like the herpes virus or certain medications. It causes distinctive red, target-shaped rashes, usually on the arms and legs, and can sometimes affect mucous membranes like the mouth. It is not contagious and typically resolves on its own.

What is Erythema Multiforme?

Erythema multiforme (EM) is a sudden, temporary skin condition that results from an immune system reaction, most often to an infection or medication. It causes a distinctive rash, commonly featuring red, target-shaped spots, and is not contagious. EM usually clears up on its own within a few weeks.

Erythema multiforme is a type of hypersensitivity reaction, meaning your immune system overreacts to a trigger. This reaction causes inflammation in the skin and sometimes in the mucous membranes, which are the moist linings inside your body, such as in the mouth or eyes. The condition is generally divided into two forms: erythema multiforme minor and erythema multiforme major. Erythema multiforme minor is the more common and less severe type, usually affecting only the skin or one mucous membrane. Erythema multiforme major is rarer and more serious, involving widespread skin lesions and often affecting two or more mucous membranes, along with more general body symptoms. Despite its appearance, erythema multiforme is not an infection itself and cannot spread from person to person. It is a reaction to something else happening in your body.

Symptoms

The main symptom of erythema multiforme is a rash with characteristic "target lesions" — red, raised spots with a darker center and a lighter ring, resembling a bull's-eye. These lesions often appear suddenly and symmetrically on the arms and legs, but can also affect other areas, including mucous membranes like the mouth.

The rash typically starts on the hands, feet, arms, and legs, often appearing on both sides of the body at the same time. The target lesions can vary in size and may sometimes blister or crust over. They can be itchy or mildly painful. In addition to the skin rash, some people may experience other symptoms. These can include a fever, general feeling of being unwell (malaise), body aches, and joint pain. When erythema multiforme affects mucous membranes, it can cause painful sores or blisters. These might appear on the lips and inside the mouth, making it difficult to eat or drink. Less commonly, sores can develop in the eyes or on the genitals. Erythema multiforme major involves more extensive skin lesions and significant mucous membrane involvement, along with more severe general body symptoms.

Causes & risk factors

Erythema multiforme is most commonly triggered by infections, especially the herpes simplex virus (HSV), which causes cold sores or genital herpes. Certain medications, such as some antibiotics or pain relievers, can also cause this reaction. It is an immune response, not a direct infection, and anyone can develop it.

The most frequent cause of erythema multiforme is an infection with the herpes simplex virus (HSV), the same virus responsible for cold sores around the mouth or genital herpes. In these cases, the EM rash usually appears about 1 to 3 weeks after the herpes infection. Another common infectious trigger is Mycoplasma pneumoniae, a type of bacteria that can cause lung infections. Certain medications can also trigger erythema multiforme. These include some antibiotics, such as penicillins and sulfonamides, as well as nonsteroidal anti-inflammatory drugs (NSAIDs), and some anticonvulsants used to treat seizures. Less common triggers can include other infections (like fungal infections or other viruses), vaccinations, or, rarely, internal cancers or radiation therapy. While anyone can develop erythema multiforme, people who frequently experience herpes simplex virus outbreaks may have a higher risk of recurrent episodes of EM.

How it's diagnosed

A doctor usually diagnoses erythema multiforme based on a physical examination of the characteristic rash and a review of your medical history. They will look for the distinctive target lesions and ask about recent infections or medications. Sometimes, a skin biopsy may be performed to confirm the diagnosis or rule out other conditions.

During the examination, your doctor will carefully inspect your skin, looking for the classic target-shaped lesions. They will also check for any involvement of your mucous membranes, such as in your mouth or eyes. Your medical history is crucial, as it helps identify potential triggers like recent herpes outbreaks or new medications. In some cases, if the diagnosis is unclear or if the rash looks unusual, your doctor might recommend a skin biopsy. This involves taking a small sample of skin to be examined under a microscope. This can help confirm erythema multiforme and distinguish it from other serious skin conditions that can look similar, such as Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN). Blood tests are not typically used to diagnose erythema multiforme directly, but they might be done to look for underlying infections, such as Mycoplasma pneumoniae, if suspected as a trigger.

Treatment options

Treatment for erythema multiforme focuses on addressing the underlying cause and relieving symptoms. If an infection like herpes simplex virus is the trigger, antiviral medications may be prescribed. Symptom relief often includes antihistamines for itching, pain relievers, and topical corticosteroids to reduce skin inflammation.

If your doctor identifies an underlying infection as the cause, treating that infection is the first step. For example, if herpes simplex virus is the trigger, antiviral medications may help shorten the duration of the EM episode or prevent future recurrences. If a medication is suspected, your doctor will advise you to stop taking it. To manage the symptoms, several treatments can help. Oral antihistamines can reduce itching. Over-the-counter pain relievers, such as acetaminophen or ibuprofen, can help with pain, fever, and body aches. Topical corticosteroids, applied directly to the skin, can help reduce inflammation and discomfort from the rash. For painful mouth sores, your doctor might recommend anesthetic mouthwashes to numb the area, making it easier to eat and drink. In severe cases of erythema multiforme major, hospitalization may be necessary for intravenous fluids, strong pain management, and specialized wound and eye care. The use of systemic corticosteroids (steroids taken by mouth or injection) for EM is debated among medical professionals, but they may be considered in severe cases.

Recovery & outlook

Erythema multiforme is usually a self-limiting condition, meaning it typically resolves on its own without specific treatment within 2 to 4 weeks. Most people make a full recovery. However, recurrences are common, especially if the trigger is the herpes simplex virus, and some individuals may experience repeated episodes.

For erythema multiforme minor, the rash generally fades within a few weeks, leaving no lasting scars. The skin may temporarily show some discoloration where the lesions were, but this usually resolves over time. Erythema multiforme major is more serious and can take longer to heal, sometimes several weeks. While most people recover fully, severe cases, especially those with extensive mucous membrane involvement, can lead to complications such as secondary skin infections, scarring in the eyes, or difficulty eating due to mouth sores. Recurrence is a significant aspect of erythema multiforme, particularly when triggered by the herpes simplex virus. Some people may experience several episodes throughout their lives. If you have recurrent EM linked to herpes, your doctor might discuss long-term antiviral therapy to help prevent future outbreaks.

When to see a doctor

You should see a doctor if you develop a new, widespread, or blistering rash, especially if it's painful or accompanied by fever. Seek immediate medical attention if you have difficulty swallowing or breathing, extensive mouth or eye sores, or if the rash is spreading rapidly, as these could indicate a more severe condition.

It is important to contact your doctor if you suspect you have erythema multiforme, particularly if it's your first time experiencing such a rash. A medical professional can accurately diagnose the condition and rule out other, more serious skin disorders that can look similar, such as Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN). Seek urgent medical care if you experience any signs of a severe reaction. These include a rash that covers a large part of your body, widespread blistering, or skin that looks like it's peeling. Also, be alert for severe pain, a high fever, or significant involvement of your eyes, mouth, or genitals that makes it hard to see, eat, or urinate. Any difficulty breathing or swallowing, or a feeling of confusion or extreme weakness, also warrants immediate medical attention. These symptoms could indicate a life-threatening emergency.

Frequently asked questions

Is erythema multiforme contagious?

No, erythema multiforme is not contagious. It is an immune system reaction within your body, not an infection that can spread from person to person.

What is the difference between erythema multiforme minor and major?

Erythema multiforme minor is less severe, typically affecting only the skin or one mucous membrane. Erythema multiforme major is more serious, involving widespread skin lesions, two or more mucous membranes, and often more general body symptoms like fever and body aches.

Can erythema multiforme come back?

Yes, erythema multiforme can recur, especially if it is triggered by the herpes simplex virus. Some people may experience repeated episodes throughout their lives.

How long does erythema multiforme last?

Erythema multiforme usually resolves on its own within 2 to 4 weeks. More severe cases, like erythema multiforme major, may take longer to heal.

Are there any home remedies for erythema multiforme?

While home remedies cannot cure erythema multiforme, cool compresses can help soothe itchy skin. Over-the-counter pain relievers like acetaminophen or ibuprofen can manage discomfort. Always consult your doctor for proper diagnosis and treatment.

Is erythema multiforme related to Stevens-Johnson syndrome (SJS)?

Erythema multiforme, Stevens-Johnson syndrome (SJS), and toxic epidermal necrolysis (TEN) are all severe skin reactions. While they share some features, EM is generally considered a distinct and less severe condition than SJS/TEN, which are life-threatening emergencies. A doctor can differentiate between them.

Sources

• MedlinePlus — Erythema Multiforme
• Mayo Clinic — Erythema Multiforme
• Cochrane Library — Erythema Multiforme