Author: Dr Tim Aung, Primary Care Practitioner, Brisbane & Logan, Queensland, Australia. DermNet Editor in Chief: Adjunct A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand. Copy edited by Gus Mitchell/Maria McGivern. April 2019.
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 primaryrash is present — just scratch marks.
Pruritus can begin within hours or up to several weeks after the drug responsible has first been administered.
Pruritus can be classified as acute (ie, present for < 6 weeks) or chronic (ie, 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 with back scratcher
Pruritus
Scratch marks
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:
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
Antimicrobials and antibiotics that cause pruritus include:
The cessation of the causative drug is an immediate priority [1,4–6]. Treatment depends on how the causative drug triggered the itching and its severity.
Topicalcapsaicin 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 the activation of mu 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 second- or third-line antipruritic agents.
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