Chronic Itch is an itch that lasts longer than 6 weeks. Some studies show that it can affect people from 8% to 25%. The prevalence also increases with age. Chronic itching is associated with higher rates of insomnia, depression, anxiety and decreased quality of life.
In chronic itching, the patient can be grouped into 1 of 2 categories.
- Having Normal Skin
- Having Lesional Skin
And then it can be broken down into 6 categories to what’s causing it.
- Dermatitis-Atopic Dermatitis (Eczema) is by far the most common cause, psoriasis, chronic urticaria. Other causes are allergic contact eczema, mastocytosis, autoimmune diseases, bullous pemphigoid, dermatitis herpetiformis, ichthyosis, cutatneous T-cell lymphoma and polymorphic exanthemas during pregnancy.
- Systemic Diseases-chronic kidney disease associated prurtisi, pruritis due to hepatobiliary disease (cholestatic pruritis), metabolic diseases (diabetes), myeloproliferative disorders (iron deficiency and lymphoma). Certain cancers such as chronic myelogenous leukemia, polycythemia vera, primary myelofibrosis and essential thrombocythemia.
- Neurologic Diseases-this can be due to the affection of the somatosensory system via metabolic, neurodegenerative, orthopedic, infectious, automimmune, malignant and iatrogenic conditions. Treatment options include gabapentin, topical anesthetics, Botox and capsaicin.
- Psychiatric/psychosomatic diseases-these patients suffer from anxiety and depressive symptoms.
- Multifactorial Causes
- Unknown Causes
For the first diagnostic steps, a general CBC including differential, C-reactive protein, Liver (AST, ALT, GGT, Alk Phos) and Kidney (Creatine, GFR), L-Lactate dehydrogenase, TSH, are all recommended with additional and more specific labs according to the clinical exam.
Based on these findings, therapy should be initiated as do what is causing the chronic itch. For the most common cause, atopic dermatitis, we have addressed the treatment in various articles published here.
The overall treatment steps can be broken down to:
Step 1: Itchy diary, use of emollients, topical steroids, topical calcineurin inhibitors, treatment of scratch-related lesions, support for sleep disturbances, stress and psychic reactions.
Step 2: Diagnose and treat the underlying cause. Consider non-sedating H1-antihistamines, topical capsaicin, UV-therapy.
Step 3: Evaluation with a specialist. Consider specific treatment options. i.e. Dupixent for eczema
Step 4: Collaboration with specialized itch centers. Consider Gabapentinoids, antidepressants, and/or opioid modulators.
Step 5: Refer to specialized itch centers. (Miami itch center, Institute of Allergy in Berlin, Itch Clinic in Singapore).
Overall the management of chronic itch relies on first diagnosing the condition and then finding the best treatment modality to treat the itch. Application of emollients to counter balance dry skin is crucial for achieving a long term reduction of itch. Addressing the skin care and prevention of further scratching related damage to the skin by interruption of the itch-scratch cycle is crucial.