Table of Contents
- What Is a Codeine Allergy?
- How Common Are Codeine Allergies?
- Symptoms of a Codeine Allergy
- What Causes Codeine Allergy?
- Risks and Complications of Codeine Allergies
- Precautions to Take with a Codeine Allergy
- How to Avoid Codeine-Containing Medications with a Codeine Allergy
- Allergies and Codeine-Containing Drugs
Key Points
- Codeine allergies can be life-threatening, but they’re an extremely rare risk of the drug.
- Allergy-like symptoms are more common with codeine, caused by a histamine reaction similar to an allergic reaction.
- Codeine pseudoallergies can occur with common allergy symptoms like itching and hives, though a true allergy can cause anaphylaxis.
Many commonly used drugs can trigger allergies in people, including codeine. This happens when the body has an immune response to the substances found in the medication. True codeine allergies are extremely rare, but it’s possible to have a pseudoallergy reaction caused by a histamine response to the drug.
What Is a Codeine Allergy?
Codeine allergies are extremely rare. Often, allergy-like symptoms include itching, hives, and nausea, which happen from a pseudoallergy effect and the body’s histamine response to the drug.
In the rare case of a true codeine allergy, however, drugs with codeine can cause potentially dangerous complications, such as anaphylaxis. This is a severe, life-threatening allergic reaction that requires emergency medical attention.
How Common Are Codeine Allergies?
A codeine allergy is an extremely rare allergy. Based on estimates, allergic reactions to codeine and other opioids only comprise less than 2% of all hypersensitivity reactions in patients undergoing anesthesia.[1]
More commonly, the symptoms considered a codeine allergy are actually pseudoallergy—or allergy-like symptoms that are uncomfortable but not dangerous, such as itching or hives. This can lead to a misguided belief that there’s an allergy to codeine or opioid drugs, but it’s not the same as a true allergy. It’s a response to the substances in the drug that causes the body to release histamine, causing the allergy symptoms.
Symptoms of a Codeine Allergy
A codeine pseudoallergy may have allergy-like symptoms, such as:[2]
- Flushing
- Itching
- Hives
- Sneezing
- Low blood pressure
- Worsening asthma
The symptoms of a true codeine allergy are more severe and may include:[3]
- Swelling of the tongue, mouth, lips, or face
- Hives
- Low blood pressure
- Respiratory distress (trouble breathing)
- Wheezing or coughing
- A rash that resembles pimples
- Erythema multiforme (bullseye-shaped lesions)
- Swelling under the skin
Anaphylaxis from codeine can have adverse effects on the heart, lungs, and other organ systems. If you experience any allergy-like symptoms from taking codeine, seek medical attention.
What Causes Codeine Allergy?
Allergies to drugs like codeine happen when the body’s immune system reacts to the substances in the drug. The body reacts to the presence of the drug by making immunoglobulin E (IgE), which removes the triggering substance.
There are different IgE types for specific allergens. The IgE travels to the histamine (mast cells) in the airways, skin, muscle membranes, and gastrointestinal tract.[4] When the drug is detected again, the IgE attaches to the allergen, and mast cells release histamine and other chemicals. The result is allergy symptoms.
T-cells, the white blood cells that respond to infection in the body, can also cause an allergic response. The T-cells recognize that the drug is a foreign body and bind to it, triggering a slower immune response that causes skin symptoms like itching and hives.[5]
Risks and Complications of Codeine Allergies
Codeine allergies are often severe, but pseudoallergies can be mild to severe. Anaphylaxis, a life-threatening condition that includes symptoms like swelling of the face and throat, severe difficulty breathing, rapid heartbeat, and a severe drop in blood pressure, can happen with allergens like codeine, though rare.
There are other risks and side effects with codeine, however, including dry mouth, nausea, vomiting, and mental confusion. Constipation often occurs with prolonged use of codeine or other opioids. Nausea and vomiting can happen initially, but these side effects usually subside as the body adjusts to the drug.
At high doses, opioids like codeine can cause toxicity – or an overdose. Opioid overdoses can be fatal and require prompt emergency medical attention. The symptoms of an opioid overdose include shallow breathing, confusion, and loss of consciousness.[6] If you think someone is overdosing on codeine or another opioid, call 911 immediately and administer naloxone while you wait for help.
Precautions to Take with a Codeine Allergy
If you have pseudoallergies from codeine or other drugs, such as hives or itching, you may be able to relieve the symptoms with an antihistamine or a lower dose under the guidance of your doctor. A pseudoallergic reaction often occurs due to the dose or potency of the drug, so a higher-potency opioid given at a lower dose and frequency may help.[7]
If you have a known allergy-type reaction to codeine and need to take opioids, it’s possible that another opioid in a different structural class may not trigger the reaction.[8] Some opioids may trigger the same response, however.
If you have a true codeine allergy, you may not be able to take any natural opioids without an allergic reaction. Synthetic opioids, such as fentanyl, may be a suitable alternative without allergy-like symptoms. However, there are other risks, such as the high potency of fentanyl and its serious risk of addiction and overdose. Talk to your doctor about your options.
How to Avoid Codeine-Containing Medications with a Codeine Allergy
If you have severe reactions to codeine, it’s best to avoid the drug altogether. Talk to your doctor about your symptoms to ensure that you aren’t prescribed drugs with codeine or other natural opioids that may trigger your allergy.
You should also pay attention to your medications. Double-check medication labels and package inserts to ensure that drugs don’t contain codeine or similar ingredients. Prescription cold medications or pain medications can have NSAIDs with other drugs, such as codeine.
If you have a true codeine allergy, consider wearing a medical alert bracelet or carrying a medical allergy card that lists your codeine allergy. This simple measure can save your life if you’re in an accident or some other emergency and can’t alert the emergency response team of your dangerous allergy.
Allergies and Codeine-Containing Drugs
Codeine allergies are rare but possible. However, it’s more likely for people to experience a pseudoallergy to codeine-containing drugs, such as hives or itching. If you have a codeine allergy, you can experience anaphylaxis and serious complications that can be life-threatening, so you shouldn’t take any drugs that contain codeine.
Frequently Asked Questions
Below are some of the most frequently asked questions regarding codeine allergies.
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