Why Does Codeine Make You Itch?

In codeine prescribing information approved by the FDA, officials list “pruritus” as a common side effect.[1] Pruritus is another word for itching, and many people experience this problem the first time they take codeine.

Like many opioids, codeine can trigger your body’s histamine response and cause full-body itching. Typically, the issue fades quickly. An over-the-counter antihistamine medication may help too.

Histamine reactions are rarely life-threatening, and a histamine response is not the same thing as an allergy to opioids–a true opioid allergy is more rare. But if you’re concerned about your itching or it worsens, talk to your doctor right away.

Why Can Codeine Make You Itch?

Your body is lined with cells that release histamine in reaction to a threat. Opioids like codeine trigger histamine cells, and when they do, significant itching begins. 

Researchers say people with histamine reactions to codeine typically experience symptoms within minutes, but the problem doesn’t last for long.[2] The body thinks you’re experiencing a threat, releases histamine to expel it, and then settles into a new normal with codeine present. 

In addition to itching, you may experience the following symptoms:[3]

• Flushed skin
• Sneezing
• Hives  
• Low blood pressure 

Higher codeine doses produce stronger histamine reactions and more significant itching. 

Ways to Reduce the Codeine Itch

People with histamine responses to codeine often get relief with over-the-counter antihistamines.[3] These drugs work directly on the cells pumping out histamine, reducing the reaction and easing your itch. 

Researchers say people have fewer symptoms with repeat administration.[4] In other words, if your cells release a lot of histamine the first time you take codeine, they may release a little less the next time you take it. Your cells can learn that the drug isn’t a threat and shouldn’t cause alarm. 

But codeine itching can be uncomfortable, especially if it comes with other symptoms like hives. If you need opioids for pain relief, your doctor may switch to a different type of medication. Researchers say drugs like Demerol don’t cause itching in the same way codeine does.[5]

People with itching due to opioids aren’t allergic to the drug. Their itches won’t progress to life-threatening symptoms (like cardiac arrest or closed airways). But anyone who has experienced itching after taking codeine might think twice about using opioids again. 

Other painkillers like aspirin work via different metabolic pathways and won’t cause itching. They could be a better choice for you, so discuss this with your doctor if you persistently itch when you take prescribed codeine.

How to Get Medical Attention if Symptoms Won’t Go Away

Most people with codeine itching don’t need emergency medical attention. You may be uncomfortable, but over-the-counter medications can ease your discomfort quickly. But some people do have life-threatening allergic reactions to codeine, and they need quick help.

A true opioid allergy can produce the following symptoms:[3]

• An uneven rash that looks flat in some areas and raised in others
• Red, raised areas all over the body, including on the fingers and inside the mouth
• Significantly low blood pressure, which might cause fainting
• Swelling around the eyes, lips or tongue
• Difficulty breathing

These symptoms are life-threatening, and they require quick medical treatment. Call 911 immediately, and explain what’s happening. The operator can tell you what to do next, and the emergency medical team can administer prescription-grade antihistamines to help. Don’t hesitate, as quick action can save a life.

If you’ve experienced a significant reaction like this, you shouldn’t take codeine again. And you should talk with your doctor before using any other type of opioid. These drugs may not be safe for you, so you can discuss alternative pain management options with them.