Codeine Allergy: Reactions, Symptoms & What to Expect

A true codeine allergy is extremely rare. Most symptoms people attribute to allergies (like itching or nausea) are caused by entirely different processes. These responses are known as pseudoallergy effects brought on by the body’s histamine response. Genuine codeine allergy symptoms involve hives, a rash, blisters, trouble breathing, dangerously low blood pressure or swelling of face, neck or mouth.

But if you’re one of the rare people with a true codeine allergy, this opioid medication could result in life-threatening consequences, such as anaphylaxis. This is a medical emergency that requires prompt treatment with epinephrine or steroids. 

Can I take opioid painkillers like Percocet, Vicodin or Norco if I am allergic to codeine?

How Common Are Codeine Allergies?

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.[1] 

Even though codeine allergies are so rare, many people believe they have them. But doctors say as many as 9 patients in 10 labeled with an opioid allergy don’t have one at all.[2] Rather, opioids like codeine can cause the body to release histamine, which can result in signs like itching, but this doesn’t indicate an allergy.[3]

Signs of a codeine pseudoallergy include:[2]

• Itching
• Hives
• Flushing
• Sneezing
• Sweating
• Low blood pressure
• Exacerbation of asthma

If you struggle with a distressing codeine reaction, you can tell your doctor about them and request a different medication or treatment. But know that you may not have a true codeine allergy.

Signs & Symptoms of a Codeine Allergic Reaction

A true codeine allergy is mediated by T-cells or IgE allergy antibodies.[2]

People with a true codeine allergic reaction develop the following symptoms:[2,][4]

• Dangerously low blood pressure
• Swelling in your tongue, lips, face or mouth 
• Respiratory distress 
• Wheezing or coughing (bronchospasm)
• Hives
• Maculopapular rash
• A rash that resembles pimples or pustules
• Erythema multiforme, including symmetrical and raised skin areas on the body, especially toes and fingers
• Angioedema, swelling under the skin

Since allergic reactions involve critical systems like your heart and lungs, you should go to an emergency room immediately. Bring your codeine pills with you, and tell the doctor how much you took. 

People May Mistake Codeine Side Effects for an Allergy

People taking codeine may experience common side effects that they mistake for a codeine allergic reaction, such as:[5]

• Nausea and vomiting
• Dizziness
• Shortness of breath (due to respiratory depression)
• Itchy skin

Although these side effects can be uncomfortable, they don’t indicate a codeine allergy—they’re simply a side effect of this opioid.

How to Treat a Codeine Allergy

If you struggle to breathe after taking codeine, go to the emergency room or call 911 immediately. The team will assess your condition and determine what to do next.

If you took oral codeine pills, the team might suction contents from your stomach, preventing more codeine from passing through the digestive tract. They may also give you fluids to help your organs process any codeine in the bloodstream. 

Medical teams can use medications like epinephrine and steroids to treat an ongoing allergic reaction.[6] These drugs quickly soothe the central nervous system and stop painful symptoms before they worsen. 

A true codeine allergic reaction is a medical emergency. It’s important to seek immediate help.

Alternatives to Codeine

If you’ve had a true allergic reaction to codeine, you shouldn’t take more. People with mild reactions may have better results with an opioid from another class. But those who had life-threatening reactions to codeine may not be willing or able to risk their health by using a similar opioid drug.

Over-the-counter (OTC) pain medications like aspirin or ibuprofen don’t work like opioids, and they can be effective painkillers. If you’re struggling with mild pain, these drugs might be a better short-term solution.

If you have long-term, chronic pain, opioids may not be the best choice available. Some people find that physical therapy, massage or yoga are more effective methods of pain control, and they don’t come with the overdose risks attached to opioids. However, if nothing else works, your doctor may prescribe a synthetic opioid like fentanyl.[2]

Ask your doctor about your solutions. Together, you can find a treatment plan that’s right for your body and your pain.