View source for Pruritus

== Differential Diagnosis ==

* Dermatologic disorders
** [[Xerosis]]
** [[Eczematous dermatitis]]
*** [[Atopic dermatitis]]
*** [[Contact dermatitis]]
** [[Urticaria]]
** Papulosquamous disorders
*** [[Psoriasis]]
*** [[Lichen planus]]
*** [[Pityriasis rubra pilaris]]
** Infections
*** [[Dermatophytes|Dermatophyte]] infections ([[tinea cruris]], [[tinea pedis]], [[tinea capitis]])
*** [[Scabies]]
** Secondary skin disorders
*** [[Lichen simplex chronicus]]
*** [[Prurigo nodularis]]
** Scars
** Others: [[bullous pemphigoid]], [[dermatitis herpetiformis]], [[mastocytosis]]
** Systemic disorders
*** [[Chronic kidney disease]], especially those on [[dialysis]]
*** Liver disease
**** [[Cholestatis pruritus]] from [[primary biliary cirrhosis]], [[intrahepatic cholestasis of pregnancy]], [[primary sclerosing cholangitis]], [[viral hepatitis]], [[drug-induced cholestasis]], [[obstructive jaundice]]
*** Endocrine disorders
**** [[Thyrotoxicosis]], especially with [[Graves disease]], more commonly than [[hypothyroidism]]
**** [[Diabetes mellitus]]
*** Malignancy
**** [[Hodgkin lymphoma]]
**** [[Polycythemia vera]]
**** [[Mycosis fungoides]]
**** Other hematologic malignancies
**** [[Gastric carcinoid]]
*** Infections
**** Primary [[varicella]]
**** [[HIV]]
*** Rheumatic disorders, including [[dermatomyositis]], [[systemic sclerosis]], [[Sjögren syndrome]]
*** Drug reactions, including drug-induced dry skin from retinoids or phototoxicity from [[doxycycline]]
** Neuropathic itch
*** [[Brachioradial pruritus]]
*** [[Notalgia paresthetica]]
*** [[Postherpetic neuralgia]]
*** [[Multiple sclerosis]]
*** Other small fiber neuropathy
** [[Chronic pruritus of unknown origin]]
** Psychogenic itch, including [[psychogenic excoriation]], [[delusional parasitosis]], and [[substance use disorder]]

== Investigations ==

* CBC with differential, liver tests (bilirubin, ALT, ALP), TSH, creatinine
* Consider chest x-ray