Erythema is redness of the skin caused by increased blood flow to the capillaries. There are many causes and manifestations of erythema, including photosensitivity, erythema multiforme, and erythema nodusum. Photosensitivity refers to a skin reaction in response to the sun; it tends to occur when something, such as an infection or a medication, increases a person's sensitivity to ultraviolet radiation. Erythema multiforme is characterized by spots, blisters, or other lesions on the skin and usually results from a reaction to medications, infections, or illness. Erythema nodosum is a form of erythema that is accompanied by nodules, small round masses, typically on the arms and legs.

What Causes It?

In half of all cases of either erythema multiforme or erythema nodosum, the exact cause is not identified. The following are examples of what may precipitate these skin reactions.

Erythema multiforme:

  Who's Most At Risk?

  Signs and Symptoms

Erythema multiforme:

Erythema nodosum:

  What to Expect at Your Provider's Office

  Healthcare providers will perform a physical exam and may use procedures such as a skin biopsy, throat culture, blood test, or X ray to determine the type of erythema. Not only will these procedures help identify the type of skin condition, they may also reveal any infections or medications that are contributing to the symptoms.

Treatment Options


Treat any underlying diseases and avoid any known triggers (certain medications, for example); it is also important to avoid being outside in the sun when taking certain medications that contribute to photosensitivity.

  Treatment Plan

Healthcare providers will treat any underlying diseases, eliminate drugs that may contribute to symptoms, and take steps to control current symptoms. While mild cases may not require treatment, bed rest and medication may be necessary for more severe cases.

Drug Therapies

Healthcare providers may prescribe various medications in the appropriate clinical setting, including:

  Complementary and Alternative Therapies

In order to heal any type of erythema, the underlying cause of the skin condition must be treated. Certain complementary and alternative therapies, though, help to:

Reduce inflammation





Massage should be avoided in cases of erythema because it may make any inflammation worse.

Prognosis/Possible Complications

When treated properly, signs and symptoms of erythema multiforme usually disappear in four to six weeks; symptoms of erythema nodosum, however, may reappear for up to two years. Symptoms of SJS typically disappear in a month, but when the condition is not treated properly it may lead to blindness. Ten percent may die from more severe forms of SJS. Up to 40 percent of those with TEN may die of the condition. If the drug causing either SJS or TEN is identified and discontinued quickly, a person's chance of survival significantly improves.

  Following Up

Healthcare providers will monitor fluid and electrolyte levels, protein loss, and any organ damage. Persons with erythema multiforme may need treatment in a hospital burn unit if 20% or more of their body is affected.

Special Considerations

Erythema raises special issues related to pregnancy. If a pregnant woman develops erythema infectiosum (fifth disease), the virus can infect the fetus and cause fetal anemia, heart failure, hydrops (collection of watery fluid), and even death. Studies have also shown that pregnancy may trigger erythema nodosum. Finally, certain medications must be avoided during pregnancy; your healthcare provider will be able to direct your care appropriately.