Analgesia, Anaesthesia and Pregnancy. 4th Ed. Róisín Monteiro

Chapter 57. Opioid-induced pruritus

Itching can result from the administration of opioids by any route, but it is much more common following epidural and intrathecal opioids than after systemically administered opioids. The reported incidence of itching varies from 0% to 100%, and it is sometimes only discovered as a result of observing the patient or asking direct questions. Severe itching is only a problem in a very small number of cases (possibly as low as 1%). The incidence of itching associated with opioids is higher in the obstetric population, probably owing to an oestrogenic influence at the opioid receptors.

Facial itching predominates after epidural and intrathecal opioids. This is possibly related to migration of opioid in the cerebrospinal fluid to the trigeminal nucleus and the trigeminal nerve roots. More generalised itching occurs with systemically administered opioids and may be due to activation of peripheral opioid receptors and partly to histamine release (especially with morphine). The mechanism of opioid-induced itching is still not completely understood; suggested mechanisms include modulation of the serotonergic pathway and activation of the medullary dorsal horn.

Problems and special considerations

The incidence of pruritus varies considerably between different opioids, being highest with morphine and lowest with the most lipophilic drugs such as fentanyl and sufentanil. Mixed agonist-antagonist drugs such as buprenorphine and butorphanol have been used via the epidural route to reduce the incidence of itching without decreasing analgesia.

Itching following administration of intrathecal fentanyl for caesarean section does not appear to predict that itching will also occur after epidural administration of diamorphine for postoperative analgesia.

Management options

No treatment is necessary for opioid-induced itching unless the mother is distressed. Simple antihistamines may be effective, but this may be through their sedative effect. Naloxone is an effective treatment for pruritus, but reduces the duration of analgesia obtained with neuraxial opioids, although a low-dose continuous infusion (0.4-0.6 mg/h) of naloxone is said to treat itching while maintaining analgesia from intrathecal morphine. A systematic review has suggested that prophylactic 5-HT3 receptor antagonists, such as ondansetron, may reduce the severity of pruritus.

A variety of other treatments have been proposed, including intravenous droperidol, subhypnotic doses of propofol, nalbuphine and intramuscular promethazine. There is little evidence that any are effective.

Key points

 Itching can occur following the administration of any opioid drug by any route, but is most common following the epidural or intrathecal administration of morphine.

 Although the incidence of pruritus may exceed 90%, it is not often distressing for the mother and may not require any treatment other than reassurance.

Further reading

Bonnet MP, Marret E, Josserand J, Mercier FJ. Effect of prophylactic 5-HT3 receptor antagonists on pruritus induced by neuraxial opioids: a quantitative systematic review. Br J Anaesth 2008; 101: 311-19.

Kumar K, Singh SI. Neuraxial opioid-induced pruritus: an update. J Anaesthesiol Clin Pharmacol 2013; 29: 303-7.

Waxler B, Dadabhoy ZP, Stojiljkovic L, Rabito SF. Primer of postoperative pruritus for anesthesiologists. Anesthesiology 2005; 103: 168-78.



If you find an error or have any questions, please email us at admin@doctorlib.info. Thank you!