Is itchy skin a common side effect of morphine (opioid)?

From the Guidelines

Itchy skin is a common side effect of morphine, occurring in 10% to 50% of patients receiving opioids. This is according to the most recent and highest quality study available, which was published in 2019 in the Journal of the National Comprehensive Cancer Network 1. The study states that pruritus or itchiness is a particularly common and distressing complaint, and that it can occur even with attentive skin care.

Some key points to consider:

• The incidence of pruritus can vary depending on the route of administration, with higher rates seen in patients receiving intravenous, epidural, or intrathecal opioids 1.
• The itching typically occurs on the face, neck, and upper torso, but can be generalized.
• Opioids activate mu-opioid receptors that trigger histamine release and also directly affect the central nervous system's itch pathways.
• If you experience itching while taking morphine, don't stop the medication abruptly, but consult your healthcare provider.
• They may recommend antihistamines like diphenhydramine (25-50mg every 4-6 hours as needed), adjust your opioid dose, switch to a different opioid that causes less itching (like fentanyl), or prescribe opioid antagonists that specifically target this side effect without reducing pain control 1.

It's worth noting that the management of opioid-induced pruritus may involve a combination of these approaches, and that careful titration of mixed opioid agonist-antagonists or mu-opioid receptor antagonists may help reduce opioid-induced adverse effects 1. However, the most important thing is to consult with your healthcare provider to determine the best course of action for your specific situation.

From the FDA Drug Label

Skin and Appendages: dry skin, urticaria, pruritus The most relevant text from the drug label is the section on Skin and Appendages, which lists pruritus (itchy skin) as a common adverse reaction associated with morphine use.

• Pruritus is directly mentioned as one of the adverse reactions.
• This indicates that itchy skin is a known side effect of morphine. 2

From the Research

Opioid-Induced Itch

• Itchy skin, or pruritus, is a known side effect of morphine and other opioids 3, 4, 5, 6, 7.
• The exact mechanisms of opioid-induced pruritus are not fully understood, but possible causes include histamine release, opioid-receptor mediated effects, and idiosyncratic drug reactions 3.
• Opioid-induced pruritus can be troublesome and affect patients' quality of life and motivation to continue opioid treatment 5.

Incidence and Treatment

• The incidence of opioid-induced pruritus differs with different opioids and routes of administration 7.
• Various treatments have been used for opioid-induced pruritus, including opioid receptor antagonists, mixed agonist and antagonists, and serotonin 5-HT(3) receptor antagonists like ondansetron 4, 5, 7.
• A multimodal analgesic treatment regimen combined with a mixed antagonist and κ agonists, especially μ-opioid antagonists, and κ-opioid agonists, seems to be the current best treatment modality for the management of opioid-induced pruritus and pain 7.

Morphine-Specific Effects

• Morphine, in particular, has been associated with pruritus, as well as other cutaneous adverse reactions like urticaria, erythema, and pseudoallergic anaphylactoid reactions 6.
• A case study reported severe morphine-induced itch that was unrelieved by antihistamines but responded to a change to hydromorphone 3.