Itching in the ED

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I think one of the most uncomfortable things in the world is being itchy. As a girl who has been taking an Allegra every single day since I was 8 years old, I thought we could do a bit of a deep dive into being itchy. 


The medical term for itch is defined as pruritus. Itches can be categorized into four big groups: Neurogenic, psychogenic, neuropathic, and pruitrioceptive causes. 


  1. Neurogenic itching: thought of as more of a systemic itch, the itch starts from the central nervous system as a result of other disorders of organ systems besides the skin. 

    1. This can be seen in patients with chronic renal failure, liver disease, hematologic and lymphoproliferative diseases and malignancies

    2. The pathophysiology behind this is not completely understood but it is not through a direct neuronal pathway and often improves with opioids 

    3. The thought behind this is that these pathologies cause increase secretion of intraspinal endogenous opioids which is why it is partially responsive to opioid antagonists 

  2. Psychogenic itching: usually a diagnosis of exclusion as the pathophysiology is not fully understood

    1. Usually presents with impulses to scratch or pick 

    2. Often associated with depression, OCD, anxiety, mania, substance induced psychosis, or somatoform disorders 

    3. Most well known is parasitosis: a specific delusion where patients believe there is some sort of insect or parasite living under their skin that they must scratch away 

  3. Neuropathic itch: caused by central or peripheral neurons that are damaged that inappropriately fires pruritic neurons causing the sensation of itching without any cutaneous etiology. 

    1. Often accompanied by paresthesia, hyperesthesia, hypoesthesia  

    2. The exact mechanism is unknown though thought to be due to specific damage due to the C fibers

  4. Pruritoceptive Itch: most common encountered. Usually generated by through inflammation thorough skin damage 

    1. This is a plug to TRULY look at a patient’s skin. If there is a rash besides urticaria or wheals, that sets you down an entirely different pathway, which is not the purpose of this discussion. This discussion is for good old, generalized, full body itching. 

    2. To avoid a true histologic lecture, the short of it is that itching is perceived through C fibers that are unmyelinated that are able to interact with keratinocytes in skin that react directly to pruritogens. 

    3. There is a theory that the nerves that perceive pain (nocireceptors) are able to block the sensation of itching therefore scratching does not relieve itching but rather it just blocks the sensation of itching providing temporary relief 

    4. Certain mediators are able to trigger the response of itching: 

      1. Histamine

      2. Triptase

      3. Interleukin 34

      4. Leukotrine B4

      5. Substance P


Okay- so now that we understand at a cellular level what is causing a patient to itch- now what? 

  1. As always the first step is determining if this is a systemic or local process: 

    1. Is this coming from a neurogenic perspective for example does this patient have renal failure or CKD and maybe this pruitius is a symptom of their worsening uremia? 

    2. Does this patient have a systemic rash, swelling of the oropharynx and recently ate a dish with peanuts that they have a known allergy to? Consider anaphylaxis and a hypersensitivity reaction and treat appropriately 

    3. Does the patient have an infectious reason for their itching? Are they covered in little insect bites? Do they have lice in their hair? Consider there are many little critters that will cause generalized itching 

  2. Stabilize the patient 

    1. Go back to your ABCs 

  3. Determine if there is a need for additional work up?

    1. Does this patient need labs to see if there is an infectious etiology or end organ damage? Consider a CBC, BMP, LFTs, lipase 

  4.  If truly just urticaria: treat!

    1. Non-pharmacological interventions:

      1. Moisturizer: avoid fragrances 

      2. Cool environments: cold packs, ice, cool shower

      3. Avoid irritants 

    2. Topical therapies: 

      1. Corticosteroids 

        1. Avoid the face and long term use 

      2. Capsicin

    3. Systemic therapies:

      1. Antihistamines: Benadryl (sedating) vs cetirizine/loratadine (nonsedating)

      2. Other more extreme causes with other systemic, noncutaneous causes can consider opioids, SSRIs, or immunosuppressants

      3. Corticosteroids
        I would be wary about starting any of these in patients outpatient or long term and encourage these patients to follow up outpatient


Well, now that we are all sufficiently scratching, heres at least a start to approaching that itchy patient in 22 hallway!

Garibyan L, Rheingold CG, Lerner EA. Understanding the pathophysiology of itch. Dermatol Ther. 2013 Mar-Apr;26(2):84-91. doi: 10.1111/dth.12025. PMID: 23551365; PMCID: PMC3696473.


Lerner EA. Pathophysiology of Itch. Dermatol Clin. 2018 Jul;36(3):175-177. doi: 10.1016/j.det.2018.02.001. Epub 2018 Mar 20. PMID: 29929590; PMCID: PMC6022764.


Macy E. Practical Management of New-Onset Urticaria and Angioedema Presenting in Primary Care, Urgent Care, and the Emergency Department. Perm J. 2021 Nov 22;25:21.058. doi: 10.7812/TPP/21.058. PMID: 35348101; PMCID: PMC8784078.


Nowak DA, Yeung J. Diagnosis and treatment of pruritus. Can Fam Physician. 2017 Dec;63(12):918-924. Erratum in: Can Fam Physician. 2018 Feb;64(2):92. PMID: 29237630; PMCID: PMC5729138.

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