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 also supports this diagnosis.
- Other Likely diagnoses
- Allergic reaction to collagen supplement: The patient started drinking collagen the day before symptoms appeared, which could be causing an allergic reaction.
- 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 other allergies.
- Urticaria: The patient's symptoms of itchiness and rash, as well as the fact that Benadryl and Zyrtec are not working, could suggest urticaria.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Stevens-Johnson syndrome: Although rare, this condition is a medical emergency that can be caused by an allergic reaction to medications or supplements. The patient's symptoms of full body rash and lack of response to antihistamines warrant consideration of this diagnosis.
- Toxic epidermal necrolysis: Similar to Stevens-Johnson syndrome, this condition is a medical emergency that can be caused by an allergic reaction to medications or supplements.
- Rare diagnoses
- Pityriasis rosea: This condition is characterized by a full body rash and can be caused by a viral infection. However, the patient's symptoms of itchiness and pulsating rash are not typical of pityriasis rosea.
- Psoriasis: Although psoriasis can cause a full body rash, the patient's symptoms of itchiness and pulsating rash, as well as the recent onset, make this diagnosis less likely.