Differential Diagnosis for Full Body Rash
- Single most likely diagnosis
- Contact Dermatitis: The patient recently changed shampoos and creams, which could be causing an allergic reaction, leading to a full body rash. The fact that the rash is itchy and pulsating, and not responding to antihistamines like Benadryl and Zyrtec, suggests a possible allergic contact dermatitis.
- Other Likely diagnoses
- Atopic Dermatitis (Eczema): The patient's symptoms of itchiness and pulsating rash could be indicative of atopic dermatitis, especially if they have a history of eczema or allergies.
- Urticaria: The itchy, pulsating rash could be a sign of urticaria, which can be caused by an allergic reaction or other factors.
- Seborrheic Dermatitis: The patient's recent change in shampoos and creams could be causing a flare-up of seborrheic dermatitis, which can cause a rash on the body.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Stevens-Johnson Syndrome: Although rare, this condition can cause a severe, life-threatening rash that can be triggered by medications or infections. The patient's symptoms of a full body rash and lack of response to treatment warrant consideration of this diagnosis.
- Toxic Epidermal Necrolysis: Similar to Stevens-Johnson Syndrome, this condition can cause a severe, life-threatening rash that requires prompt medical attention.
- Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS): This rare condition can cause a severe rash, fever, and other systemic symptoms, and can be triggered by medications.
- Rare diagnoses
- Pityriasis Rosea: This condition can cause a rash with multiple dots of different sizes and shapes, but it is typically preceded by a herald patch and is more common in children and young adults.
- Keratosis Pilaris: This condition can cause small, itchy bumps on the skin, but it is typically more localized and not as widespread as the patient's symptoms suggest.
- Mastocytosis: This rare condition can cause a rash with itchy, pulsating lesions, but it is typically more chronic and associated with other systemic symptoms.