Drug-induced pruritus

Author: Dr Tim Aung, Primary Care Practitioner, Brisbane. DermNet NZ Editor in Chief: Adjunct A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand. Copy edited by Gus Mitchell. April 2019.


What is drug-induced pruritus?

Pruritus is the medical name for itching. Drug-induced pruritus is an itch caused or triggered by medication. There are various itchy drug eruptions, but generally, the term ‘drug-induced pruritus’ implies that no primary rash is present — just scratch marks.

  • Pruritus can begin within hours or up to several weeks after the responsible drug has first been administered.
  • Pruritus can be classified as acute (present for < 6 weeks) or chronic (present for > 6 weeks).
  • It can be localised or generalised.
  • Following the cessation of the causative drug, the itch may persist for days to months before resolving.
Scratching due to drug-induced pruritus

Who gets drug-induced pruritus?

The epidemiology of drug-induced pruritus is unknown. Generally, adverse drug reactions are more common in older patients and in patients taking multiple medicines.

What is the cause of drug-induced pruritus?

The cause of drug-induced pruritus is often unknown and depends on the drug. It may involve:

  • A genetic predisposition
  • Vasodilation
  • Phototoxicity
  • Neural pathways
  • Cutaneous deposition of drugs or their metabolites
  • Dry skin
  • Cholestatic liver injury
  • Another unknown mechanism [1,2].

Which drugs cause pruritus?

The most commonly reported drugs to cause pruritus are opioids (especially during spinal anaesthesia), chemotherapeutic agents, and chloroquine (affecting 60–70% of black Africans prescribed this medicine).

The main groups of drugs that cause pruritus through various mechanisms are listed below.

Antimicrobials and antibiotics

Cardiovascular medicines

  • Amlodipine
  • Diltiazem
  • Verapamil
  • Clonidine
  • Methyldopa
  • Amiodarone
  • Captopril
  • Enalapril
  • Lisinopril
  • Candesartan
  • Irbesartan

Metabolic medicines

  • Metformin
  • Gliclazide
  • Allopurinol

Neuroleptic and psychotropic drugs

Opioids and analgesics

  • Morphine
  • Codeine
  • Fentanyl
  • Oxycodone
  • Tramadol
  • Aspirin

Steroids and hormones

Chemotherapeutics and biologics

Other drugs

  • Enoxaparin
  • Hydroxyethyl starch (plasma expanders)
  • Radiopaque contrast agents [1–3]

What is the treatment of drug-induced pruritus?

Cessation of the causative drug is an immediate priority [1,4–6]. Treatment depends on how it causes itching and its severity.

  • If the pruritus is associated with dry skin or secondary dermatitis, topical steroids and moisturisers may be of benefit.
  • Topical capsaicin has been reported as useful for treating localised drug-induced pruritus.
  • Oral antihistamines are effective if the pruritus is associated with an urticaria-like mechanism. 
  • Systemic corticosteroids may be effective if there is an inflammatory pathway suspected to be involved.
  • Naloxone or naltrexone is used for pruritus caused by activation of μ-receptor in the nervous system (in the case of opioids and plasma volume expanders).
  • Ursodeoxycholic acid and cholestyramine can reduce pruritus due to cholestatic liver injury.
  • Doxepin, amitriptyline, gabapentin, paroxetine, and ondansetron can also be used as 2nd or 3rd line antipruritic agents.
  • Phototherapy can also be of benefit.

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References

  1. Reich A, Ständer S, Szepietowski JC. Drug-induced pruritus: a review. Acta Derm Venereol 2009; 89: 236–44. doi: 10.2340/00015555-0650. Journal
  2. Szepietowski JC, Reich A, Legat F. Cutaneous drugs reaction and drug-induced pruritus. In: Pruritus. Misery L, Ständer S (eds). London: Springer-Verlag 2016: 169–74.
  3. Habif TP. Exanthems and drug eruptions. In: Clinical dermatology: a color guide to diagnosis and therapy. 6th ed. Philadelphia: Elsevier Inc; 2016: 562–76.
  4. Ebata T. Drug-Induced Itch Management. Curr Probl Dermatol 2016; 50: 155–63. doi: 10.1159/000446084. Journal
  5. Page EH. Itching - dermatologic disorders. In: Manual of diagnosis and therapy by Merckmanuals. Available at: https://www.msdmanuals.com/professional/dermatologic-disorders/approach-to-the-dermatologic-patient/itching (accessed 28/06/2018).
  6. Patel T, Yosipovitch G. Pruritus. In: Dermatologic principles and practice in oncology: conditions of the skin, hair, and nails in cancer patients (Ed by Lacouture ME). Hoboken, New Jersey: John Wiley & Sons Inc; 2014: 122–8.
  7. Sim DW, Park KH, Park HJ, Son YW, Lee SC, Park JW, Lee JH. Clinical characteristics of adverse events associated with therapeutic monoclonal antibodies in Korea. Pharmacoepidemiol Drug Saf. 2016 Nov;25(11):1279-1286. doi: 10.1002/pds.4049. Epub 2016 Jun 30. PubMed PMID: 27364925.

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