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.

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:

• Infection—primarily herpes simplex virus (HSV) and pneumonia caused by a particular type of organism called mycoplasma; influenza A and Epstein–Barr virus (the organism that causes mononucleosis) may also lead to erythema multiforme
• Medications—penicillin and other antibiotics such as a class containing sulfa; anticonvulsant medications; 5-fluorouracil used for certain forms of cancer
• Radiation therapy
• Cancer
• Chemicals

Erythema nodosum:

• Infections—including tuberculosis and HSV
• Connective tissue disorders such as lupus
• Pregnancy
• Ulcerative colitis
• Medications—oral contraceptives; a class of antibiotics containing sulfa

• Men are at greater risk than women for erythema multiforme.
• Women, on the other hand, are at greater risk for erythema nodosum.
• Excessive sun exposure increases the risk for erythema multiforme.
• Individuals with a family history of skin conditions have a greater chance of developing either erythema multiforme or erythema nodosum.

Erythema multiforme:

• Malaise, fever, itching of skin (before lesions appear)
• Sudden outbreak of spots, bumps, and lesions (typically on knees, elbows, palms, hands, feet, and mouth; trunk in severe cases)
• Target lesions (central lesion surrounded by concentric rings of normal and red skin)
• Erythema infectiosum (caused by a virus and known as fifth disease)—facial rash and rash on arms lasting about two weeks

Erythema nodosum:

• Malaise, fatigue, flu-like symptoms (before lesions appear)
• Clustures of nodules (small round masses) and lesions on shins, forearms, thighs, and trunk
• Red, hard, painful lesions become soft and bluish, and fade to yellow and brown
• Joint pain
• Arthritis

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN), perhaps the most severe forms of erythema multiforme, are characterized by a different set of symptoms. Target lesions on the trunk, hacking cough, fever, and blisters around the mouth, eyes, nostrils, and anal and vaginal areas are the key symptoms of SJS. A person with TEN will have symptoms of SJS that eventually worsen to include peeling and detachment of the skin, pus-like infections, fluid loss, and even death.

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.

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.

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.

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

• Antihistamines for itching
• Antibiotics to treat particular infections
• Antiviral medications such as acyclovir and valacyclovir
• Burrow's compresses—a solution used to soothe skin conditions, particularly blisters
• Immune-suppressing drugs, such as azathioprine, have shown mixed results
• Intravenous immunoglobulin has been used experimentally for SJS and TEN
• Steroids—topical for particular skin lesions; oral prednisone to reduce symptoms of erythema nodosum and to prevent recurrence of erythema multiforme, although this use is controversial

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
• Boost the immune system
• Prevent infections

Antioxidants found in some dietary supplements and topical preparations such as gels, ointments, or lotions may protect against skin damage caused by ultraviolet (UV) sun rays when used prior to exposure. Antioxidants are molecules that scavenge free radicals (highly active molecules that can injure cells and contribute to disease, including skin damage).

The following substances with antioxidant activity were found in studies to have benefit in protecting the skin in the circumstances described:

• Carotenoids appear to be effective at preventing skin damage when taken orally with or without vitamin E prior to sun exposure. Carotenoids can be found in fruits and vegetables as well as supplement form; beta-carotene is one common type.
• Flavonoids, such as quercetin, may help reduce the likelihood of developing erythema because they prevent inflammation and strengthen connective tissue; this, however, is only a theoretical benefit that has not been studied scientifically.
• Melatonin appears to have a protective effect when used topically in a gel, lotion, or ointment, either alone or in combination with topical vitamin E prior to exposure to UV radiation from the sun
• Vitamin C seems to be protective against developing erythema when used prior to sun exposure in either topical or oral form, although only when used in combination with topical or oral vitamin E
• Vitamin E seems to be protective when used prior to sun exposure in combination with either vitamin C or melatonin
• Zinc was used in a study as adjunctive treatment for a severe form of erythema multiforme similar to TEN; five out of eight people treated with zinc in addition to standard medical treatment had added benefit from this oral supplement

• Green tea (Camellia sinensis) may also protect against erythema caused by UV light because it contains antioxidants, like the micronutrients described in the section entitled Nutrition; this protection, when taken prior to exposure to UV radiation, has been suggested by animal studies as well as a recent preliminary human study.

Herbs traditionally used to heal damaged skin, promote lymph circulation, and possibly treat the underlying cause of various skin conditions may be helpful. Although these have not been tested scientifically for erythema specifically, some examples include:

• Burdock root (Arctium lappa) has been used topically for skin inflammation and wound healing
• Goldenseal (Hydrastis canadensis) has been used for infections, including those causing skin lesions
• Lemon balm (Melissa officinalis) can be applied to HSV lesions in the form of a cream or a wash
• Licorice root (Glycyrrhiza glabra) has been used topically for viruses and connective tissue disorders; should not be used orally in the case of high blood pressure
• Meadowsweet (Filipendula ulmaria) has been used for painful joints (as may be seen with erythema nodosum)
• Milk thistle (Silybum marianum) for chemical causes of skin lesions
• Slippery elm (Ulmus fulva) in combination with goldenseal root has been applied topically for treatment of open wounds
• Yarrow (Achillea millefolium) has been applied topically for skin inflammation and wound healing.

It is best and safest to see a trained, experienced herbalist for guidance about the use of herbs to treat erythema.

To date, only animal studies have shown that homeopathic remedies (Apis in particular) may help protect against UV radiation. However, an experienced homeopath would consider each individual case and may recommend treatments to address both the underlying condition and any current symptoms. Homeopathic remedies commonly used for skin conditions include:

• Apis, which has been studied in animals and seemed to protect their skin from the damaging effects of radiation
• Chininum sulphuricum 
• Rhus toxicodendron, which has been used traditionally for blisters and vesicles that are very itchy and worsen at night but improve with application of warm compresses; the person appropriate for this remedy is generally restless and has difficulty getting comfortable at night.

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

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.

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.

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.

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