Erythema marginatum in rheumatic fever is a rash that appears on the trunk and the upper parts of the arms and legs. It does not itch or cause pain.

Along with joint pain, involuntary movements, and heart problems, skin symptoms are among the main indications of rheumatic fever. However, erythema marginatum is one of the least common major signs.

Rheumatic fever and its effects on the body are caused by a group A streptococcus (GAS) infection, such as strep throat, that does not receive proper treatment.

This article explains what erythema marginatum in rheumatic fever is, including the symptoms, diagnosis, treatment, outlook, and prevention, as well as when to see a doctor.

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Erythema marginatum is a rash that usually appears early in the course of rheumatic fever and disappears quickly. While it is one of the major signs of rheumatic fever, it is one of the least common, occurring in fewer than 6% of people with the condition.

What is rheumatic fever?

Rheumatic fever — sometimes called acute rheumatic fever — is an inflammatory condition that can cause swelling in the joints, brain, heart, and skin. Aside from skin symptoms, the effects of the swelling may include:

  • arthritis
  • involuntary body movements
  • carditis, which is inflammation of the heart

Carditis can lead to heart conditions such as heart failure, in which the heart cannot pump enough blood throughout the body.

What is erythema marginatum?

Erythema margination is a rare type of skin discoloration. It happens more often in children (ages 5–15 years) than in adults. Although it has links to other conditions, it most commonly occurs in rheumatic fever.

Learn more about rheumatic fever.

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Binotto, M., Guilherme, L., & Tanaka, A. (2002). Rheumatic Fever. Images in paediatric cardiology, 4(2), 12–31.

Erythema marginatum causes painless, non-itchy spots of discoloration on the trunk and the upper parts of the arms and legs. The lesions spread outward, with the central part becoming clear.

The rash may worsen with exposure to heat. When it disappears, it leaves only a mild reduction in skin pigment. No scaling or wasting away of tissue occurs.

Rheumatic fever is the most common cause of erythema margination. This condition may occur when a person’s immune system responds in an atypical manner to an earlier GAS infection that did not receive proper treatment.

GAS bacteria can cause strep throat, scarlet fever, and a skin infection called impetigo, but strep throat is the infection that most often has a link to rheumatic fever.

If a person has a sore throat that does not improve or worsens after a few days, they should seek medical advice. A doctor can test for strep throat and provide treatment if necessary. This could help prevent rheumatic fever and its effects, including erythema marginatum.

A person should also consult a doctor if they have a rash or any other concerning symptoms.

A medical history and a physical examination can provide key information for a diagnosis because carditis associated with rheumatic fever generally appears 2–5 weeks after strep throat. Erythema marginatum can occur before, after, or at the same time as carditis.

Doctors may find the rash challenging to identify on darker skin.

Lab tests may also be necessary. These can include:

  • throat culture for GAS
  • blood culture
  • blood tests for various substances, such as complete blood counts
  • skin biopsy

If heart symptoms are present, a doctor may order additional tests, including an EKG, which measures the electrical activity of the heartbeat, and an echocardiogram, which shows the structure and function of the heart.

Treatment can address the cause of rheumatic fever but does not change the course of the rash. There is no treatment for the rash itself since it disappears on its own.

Because a GAS infection is the cause of rheumatic fever, first-line treatment involves a long-term regimen of the antibiotic penicillin. If a person has an allergy to penicillin, a doctor will prescribe an antibiotic from another class.

Learn more about penicillin allergies.

The rash can come and go repeatedly or linger for a few days during or after rheumatic fever.

Because erythema marginatum most commonly has an association with rheumatic fever, which can lead to rheumatic heart disease, it is beneficial to try to prevent rheumatic fever. This involves avoiding strep infections.

Frequent handwashing is the best means of prevention.

It can also be helpful to avoid eating or drinking with the same dishes and utensils as someone who is sick. Only after someone has washed these items are they safe for another person to use.

Learn more about rheumatic heart disease.

Erythema marginatum in rheumatic fever can happen if a person contracts strep throat and does not receive proper treatment. It is a non-itchy, painless rash that appears on the trunk and the upper parts of the arms and legs.

The diagnosis may entail a medical history, a physical examination, and lab tests such as cultures and blood tests. A skin biopsy is rarely necessary.

Since the rash disappears on its own, doctors do not treat it. However, they do treat the infection — the cause of rheumatic fever — with an antibiotic. Erythema marginatum can recur or persist for a few days.

Prevention involves measures to avoid contracting strep throat, such as frequent handwashing.

A person should consult a doctor if they have a rash or if they have a sore throat that lingers or worsens.