Erythema multiforme
Erythema multiforme is a skin condition that appears with red patches evolving into "target lesions" (typically the lesion exists on both hands). It is a type of erythema possibly mediated by infection or drug exposure.

The condition varies from a mild, self-limited rash to a severe, life-threatening form known as erythema multiforme major that also involves mucous membranes. Invasion of the mucous membrane or the presence of bullaes are important signs of severity.

- Erythema multiforme minor: typical targets or raised, edematous papules distributed acrally
The mild form usually presents with mildly itchy (but itching can be very severe), pink-red blotches, symmetrically arranged and starting on the extremities. Resolution of the rash within 7–10 days is the norm in this form of the disease.

- Erythema multiforme major: typical targets or raised, edematous papules distributed acrally with involvement of one or more mucous membranes. Epidermal detachment involves less than 10% of total body surface area.

Treatment ― OTC Drugs
If it is accompanied by a fever (rising body temperature), it is recommended to visit the hospital as soon as possible.
Suspected drugs should be discontinued. (e.g. antibiotics, nonsteroidal anti-inflammatory drugs)
Oral antihistamines such as cetirizine and loratadine for itching.
#Cetirizine [Zytec]
#LevoCetirizine [Xyzal]
#Loratadine [Claritin]
  • Erythema multiforme minor ― Note that the centers of the lesions may blanch.
  • Target lesions on the leg
  • Urticaria may also be considered as a differential diagnosis.
  • Target lesion of Erythema multiforme ― It may also be an early symptom of TEN, which causes widespread blisters.
  • Typical manifestation of Erythema multiforme
  • Lyme disease should also be considered. cf) Bulls eye of Lyme Disease Rash
References Recent Updates in the Treatment of Erythema Multiforme 34577844 
Erythema multiforme (EM) is an immune-mediated condition that classically presents with discrete targetoid lesions and can involve both mucosal and cutaneous sites. While EM is typically preceded by viral infections, most notably herpes simplex virus (HSV), and certain medications, a large portion of cases are due to an unidentifiable cause. Treatment for acute EM is focused on relieving symptoms with topical steroids or antihistamines. Treatment for recurrent EM is most successful when tailored to individual patients. First line treatment for recurrent EM includes both systemic and topical therapies. Systemic therapies include corticosteroid therapy and antiviral prophylaxis. Topical therapies include high-potency corticosteroids, and antiseptic or anesthetic solutions for mucosal involvement. Second-line therapies for patients who do not respond to antiviral medications include immunosuppressive agents, antibiotics, anthelmintics, and antimalarials
 Use of steroids for erythema multiforme in children 16353829 
In most cases, mild erythema multiforme is self-limited and resolves in 2 to 4 weeks. Stevens-Johnson syndrome is a serious disease that involves the mucous membranes and lasts up to 6 weeks. There is no indication for using steroids for the mild form. Use of steroids for erythema multiforme major is debatable because no randomized studies clearly indicate which children will benefit from this treatment.
 Drug-induced Oral Erythema Multiforme: A Diagnostic Challenge 29363636 
We report a case of oral erythema multiforme (EM) secondary to TMP/SMX that presented with oral and lip ulcerations typical of EM without any skin lesions and highlights the importance of distinguishing them from other ulcerative disorders involving oral cavity. The patient was treated symptomatically and given tablet prednisolone. The condition improved with stoppage of TMP/SMX therapy.
 Erythema Multiforme: Recognition and Management. 31305041
Erythema multiforme is a reaction involving the skin and sometimes the mucosa, triggered by the immune system. Typically, it manifests as target-like lesions, which may appear isolated, recur, or persist. These lesions usually symmetrically affect the extremities, particularly their outer surfaces. The main causes include infections like herpes simplex virus and Mycoplasma pneumoniae, as well as certain medications, immunizations, and autoimmune diseases. Distinguishing erythema multiforme from urticaria relies on the duration of lesions; erythema multiforme lesions remain fixed for at least seven days, while urticarial lesions often vanish within a day. Although similar, it's crucial to differentiate erythema multiforme from the more severe Stevens-Johnson syndrome, which typically presents widespread erythematous or purpuric macules with blisters. Managing erythema multiforme involves symptomatic relief with topical steroids or antihistamines and addressing the underlying cause. For recurrent cases associated with herpes simplex virus, prophylactic antiviral therapy is recommended. Severe mucosal involvement may necessitate hospitalization for intravenous fluids and electrolyte replacement.