Medical Advisory BoardAll articles are reviewed for accuracy by our Medical Advisory Board
Educational purpose only • Exercise caution as content is pending human review
Article Review Status
Submitted
Under Review
Approved

Last updated: June 16, 2025View editorial policy

Personalize

Help us tailor your experience

Which best describes you? Your choice helps us use language that's most understandable for you.

Differential Diagnosis for Bright Red Erythematous Rash on Trunk and Upper Thighs

  • Single Most Likely Diagnosis
    • Contact Dermatitis: This is a common condition that can cause a bright red erythematous rash, especially if the patient has come into contact with an allergen or irritant. The rash is often itchy and can appear on any part of the body, including the trunk and upper thighs.
  • Other Likely Diagnoses
    • Eczema (Atopic Dermatitis): A chronic skin condition characterized by itchy, inflamed skin, which can appear as a bright red erythematous rash on the trunk and upper thighs.
    • Psoriasis: An autoimmune condition that can cause red, scaly patches on the skin, including the trunk and upper thighs.
    • Allergic Reaction: An allergic reaction to a medication, food, or other substance can cause a bright red erythematous rash on the trunk and upper thighs.
  • Do Not Miss Diagnoses
    • Toxic Epidermal Necrolysis (TEN): A life-threatening condition that can cause a bright red erythematous rash, often accompanied by blistering and peeling of the skin. It is usually caused by a medication reaction.
    • Stevens-Johnson Syndrome: A rare but serious condition that can cause a bright red erythematous rash, often accompanied by blistering and peeling of the skin, as well as mucous membrane involvement.
    • Septicemia: A bacterial infection that can cause a bright red erythematous rash, often accompanied by fever, chills, and other systemic symptoms.
  • Rare Diagnoses
    • Erythema Multiforme: A rare skin condition that can cause a bright red erythematous rash, often accompanied by target-shaped lesions.
    • Kawasaki Disease: A rare condition that can cause a bright red erythematous rash, often accompanied by fever, lymphadenopathy, and other systemic symptoms.
    • Sweet Syndrome: A rare condition that can cause a bright red erythematous rash, often accompanied by fever, neutrophilia, and other systemic symptoms.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

Have a follow-up question?

Our Medical A.I. is used by practicing medical doctors at top research institutions around the world. Ask any follow up question and get world-class guideline-backed answers instantly.