In conclusion, while caution is appropriate, the evidence suggests that morphine can be safely administered to most patients with a codeine allergy, particularly when the reported allergy represents an adverse effect rather than a true immunologic reaction. Having a codeine allergy is a problem some people face, making them unable to take the prescription opioid for pain or treat a cough. The following overview covers what codeine is, what a codeine allergy reaction is like and alternative options that may be available. Codeine is used to manage mild to moderate pain, where treatment with an opioid is appropriate, and when other pain treatments such as non-opioid pain medicines do not treat your pain well enough or you cannot tolerate them. Learn about what a codeine allergy is, and how to recognize true allergic reactions. Expert guidance on treatment options and safe alternatives. A histamine reaction to codeine happens when codeine activates the skin mast cells to release histamine, causing allergy-like symptoms like flushing, itching, low blood pressure, and sweating. Codeine allergies are extremely rare, but codeine can cause a histamine reaction with allergy-like symptoms. Pseudoallergies with codeine have symptoms like hives and itching, while true codeine allergies can cause life-threatening complications like anaphylaxis. Very few people have true allergies to codeine. In fact, doctors say allergic reactions to opioids like codeine make up less than 2% of all hypersensitivity reactions in patients undergoing anesthesia. Does the patient have any known allergies? When patients say they're allergic to an opioid, are all opioid analgesics off limits? The key is getting a detailed description of the reaction. Answer the questions below and follow the instructions to find the best options for your patient. Codeine reactions are often mistaken for allergies. Learn how to distinguish common side effects and histamine release from a true, dangerous immune response. True allergic reactions to codeine exist but are exceedingly rare. For patients allergic to codeine, NSAIDs (ibuprofen 400–600 mg or naproxen) should be the first-line therapy for mild-to-moderate pain, and when opioids are required, tramadol, oxycodone, hydrocodone, morphine, fentanyl, or hydromorphone are all safe alternatives that do not cross-react with codeine allergy. 1.