Hives from morphine: what to know

Morphine can be followed by flushing, itch, or raised welts without proving a classic allergy. The reaction may be limited to the skin, but hives can also occur with deeper swelling of the face, lips, or tongue, known as [Angioedema](/conditions/angioedema/). The care team will consider the dose, route, timing, other medicines, and symptoms such as dizziness or breathing change. A [Skin Rash](/symptoms/skin-rash/) that stays fixed or hurts may need a different explanation.

If you are in a hospital or clinic, tell the nurse or prescriber immediately; do not leave or take another dose without guidance. If you are at home, contact the prescribing team promptly and keep the medicine information available. Do not drive if you feel faint or drowsy. A clinician may choose a different pain plan and may advise [Antihistamine Treatment](/treatments/medical-dermatology/oral-antihistamine-therapy/). Record whether the [Itchy Skin](/symptoms/itchy-skin/) began after an injection, tablet, or another opioid.

Call emergency services for slowed or difficult breathing, wheezing, throat tightness, trouble swallowing, faintness, confusion, or swelling of the tongue or mouth. Seek urgent assessment for rapidly spreading hives, severe dizziness, repeated vomiting, or worsening [Skin Swelling](/symptoms/skin-swelling/). Opioid-related drowsiness can be dangerous when it is paired with breathing changes, so do not wait for the rash to settle.

Was this likely histamine release or an allergy, and how should it be recorded? Which pain medicines are suitable alternatives? Should I avoid other opioids? What should I do if [Hives](/conditions/urticaria/) or swelling returns?