Erythema multiforme (EM) is a skin condition that often prompts questions about its ability to spread. This rash is not contagious and cannot be transmitted from person to person. It develops as an internal immune response, not an infection that can be passed on. This condition is a hypersensitivity reaction that primarily affects the skin and sometimes mucous membranes.
Understanding Erythema Multiforme
Erythema multiforme is an immune-mediated reaction affecting the skin and occasionally mucous membranes. It presents with characteristic “target lesions,” which are round, red patches with concentric rings, resembling a bull’s-eye. These lesions often appear symmetrically on the extremities, including the hands and feet, and can spread to other areas of the body.
The underlying cause is an immune system response to certain triggers. Infections are the most common, accounting for about 90% of cases. The herpes simplex virus (HSV), responsible for cold sores, is the most frequent infectious trigger, often preceding the rash by several days. Other infections, such as Mycoplasma pneumoniae, can also induce this reaction.
Medications, including certain antibiotics, nonsteroidal anti-inflammatory drugs (NSAIDs), and anti-epileptics, are less common but recognized triggers. Erythema multiforme is a self-limiting condition, meaning it usually resolves on its own over time.
Why Erythema Multiforme Isn’t Contagious
Erythema multiforme is not contagious because it stems from an individual’s immune system reacting internally. The rash itself is a manifestation of this internal immune response, specifically a type IV hypersensitivity reaction where T-lymphocytes target skin cells. This means the body mistakenly identifies certain proteins, often from a prior infection or medication, as threats and launches an immune attack against its own skin cells.
While an underlying infection, such as the herpes simplex virus, can be contagious, the resulting erythema multiforme rash is not. Someone exposed to the virus might contract the infection, but they will not develop erythema multiforme simply by touching the rash or sharing items. The condition is an individual’s unique immune reaction. Therefore, there is no risk of person-to-person spread of the rash itself.
Living With Erythema Multiforme
Living with erythema multiforme involves managing symptoms and understanding its self-resolving nature. Most cases are mild and resolve without specific treatment, typically within two to four weeks. Symptomatic relief often includes oral antihistamines or topical corticosteroids to alleviate itching and discomfort. For painful lesions, especially those affecting the mouth, oral rinses with local anesthetics can provide relief and aid in eating and drinking.
Identifying and avoiding triggers is important for management, particularly for recurrent episodes. If herpes simplex virus is a frequent cause, a healthcare provider might prescribe antiviral medications to help prevent future outbreaks of both the virus and the associated rash. Seek medical attention if symptoms are severe, involve widespread skin blistering, affect mucous membranes like the eyes, mouth, or genitals, or if there are signs of systemic illness such as fever or significant pain. While uncomfortable, erythema multiforme resolves without scarring.