Diagnosis
H&P
DDx and Etiology.
Diagnostic studies
-CBC, CMP (fasting glucose, Alk phos, BUN, Creatinine), TSH
-Consider skin biopsy.
-Consider scraping (KOH, mineral oil)
-Consider culture (fungal, viral, bacterial)
-Consider HIV test and CXR if a systemic condition is suspected (generalized pruritus, pruritus > 3 weeks, H&P)
Algorithm from the AAFP.
Treatment
Treat based on cause.
Nonpharmacologic treatment for all patients.
Pharmacologic treatment.
Topical anti-itch mediations
-Eucerin calming itch relief lotion.
-Benadryl itch stopping cream (Diphenhydramine / Zinc acetate)
Systemic anti-itch medications
-1st and 2nd-generation antihistamines for pruritus from urticaria or allergic dermatitis.
Further Reading / Reference
Am Fam Physician. 2011 Jul 15;84(2):195-202. A Diagnostic Approach to Pruritus. http://www.aafp.org/afp/2011/0715/p195.html