Peanut Allergy Prevention: When and How to Introduce Peanut to Infants

For years, parents were told to wait. Wait until age two or three to give their baby peanut butter. Wait until the child was older, safer, less likely to react. But the data didn’t match the advice. In 1997, about 0.4% of U.S. children had a peanut allergy. By 2010, that number had jumped to 2%. The more we delayed, the more allergies grew. Something was wrong.

The Turning Point: What the LEAP Study Changed

In 2015, a study called LEAP - Learning Early About Peanut Allergy - turned everything upside down. Led by Dr. Gideon Lack in London, researchers followed 640 babies at high risk for peanut allergy because of severe eczema or egg allergy. Half were told to avoid peanut completely. The other half got 2 grams of peanut protein - about two teaspoons of peanut butter - three times a week, starting between 4 and 11 months of age.

By age five, the difference was shocking. In the group that avoided peanut, 17% developed an allergy. In the group that ate it regularly, only 3% did. That’s an 80% drop in allergy risk. It wasn’t just a small trend. It was a revolution.

The National Institute of Allergy and Infectious Diseases (NIAID) responded quickly. In January 2017, they released new guidelines based on LEAP and other studies. These weren’t suggestions. They were clear, evidence-based rules for parents and doctors. And they worked.

Three Risk Levels, One Simple Rule

The current guidelines don’t treat all babies the same. They split infants into three groups based on risk:

• High-risk: Babies with severe eczema or egg allergy. These are the ones most likely to develop peanut allergy.
• Moderate-risk: Babies with mild to moderate eczema.
• Low-risk: Babies with no eczema or food allergies.

For high-risk babies, the window is narrow: introduce peanut between 4 and 6 months. But not just any way. Before you start, talk to your pediatrician. They may refer you to an allergist for a skin prick test or blood test. If the test is negative, you can begin. The first dose is often given in the doctor’s office - just to be safe. After that, you give 2 grams of peanut protein (about 2 teaspoons of smooth peanut butter mixed with warm water or breast milk) three times a week. Keep going until age 5.

For moderate-risk babies, no testing is needed. Just start around 6 months at home. Mix peanut butter into oatmeal, pureed fruit, or yogurt. Use smooth peanut butter only. Never whole peanuts or chunky peanut butter - choking risk.

Low-risk babies? You can introduce peanut anytime after starting solids, usually around 6 months. No special steps. Just make sure it’s safe and smooth.

Why Timing Matters - And Why 6 Months Is Key

It’s not enough to just introduce peanut. You have to do it at the right time. Studies show the sweet spot is before 6 months. A 2023 analysis combining LEAP and EAT studies found that babies who started peanut before 6 months had up to a 98% lower chance of developing an allergy - if they stuck to the plan.

Babies with mild eczema saw an 85% drop. Those with moderate eczema? 87%. Even babies with severe eczema, who were at the highest risk, had a 67% reduction. The earlier they started - and the more consistently they ate it - the stronger the protection.

And it’s not temporary. Follow-up studies from the original LEAP trial showed that even after a year of avoiding peanut, most kids who ate it early still didn’t react. That means their bodies didn’t just get used to it - they learned to accept it. That’s called tolerance, not just desensitization.

What About Oral Immunotherapy (OIT)?

You might hear about OIT - Oral Immunotherapy - as a way to treat peanut allergy. But here’s the big difference: OIT is for kids who already have the allergy. It’s not prevention. It’s treatment.

In OIT, a child eats tiny, increasing amounts of peanut under medical supervision, slowly building up their tolerance. It can reduce the chance of a severe reaction from a accidental bite. But it doesn’t cure the allergy. And it’s not risk-free - some kids have reactions during treatment.

Early introduction is the opposite. It’s for babies who don’t have peanut allergy yet. It’s about teaching the immune system not to see peanut as a threat. And it works better than anything else we’ve tried.

What Doesn’t Work - And What’s Misleading

A lot of things have been tried to prevent food allergies. Probiotics? Vitamin D? Avoiding peanut during pregnancy or breastfeeding? None of them show strong, reliable results.

Cochrane reviews - the gold standard for medical evidence - found no proof that probiotics or vitamin D reduce peanut allergy risk. And studies on maternal diet during pregnancy show no consistent benefit. The only strategy with strong, repeated, real-world results? Early peanut introduction.

And don’t be fooled by myths. You don’t need to wait for your baby to get teeth. You don’t need to wait until they’re 8 months old. You don’t need to give them whole peanuts. You don’t need to start with a tiny crumb. You need smooth peanut butter - mixed into something safe - and you need to give it regularly.

Why So Many Parents Still Wait

Even with clear guidelines, many parents don’t follow them. A 2022 study found only 38.7% of high-risk infants received early peanut introduction. Why?

Fear is the biggest reason. Parents worry about choking. They worry about a reaction. They worry they’ll do it wrong. And honestly? Some doctors don’t help. A 2023 survey found only 54% of pediatricians knew the current NIAID guidelines.

The solution? Education. Clear instructions. Support. If you’re high-risk, ask your doctor for a referral to an allergist. If you’re moderate-risk, talk to your pediatrician about how to safely introduce peanut at home. There are now products made just for this - spoonable peanut butter pouches, peanut powder mixed with baby food. They’re easier than mixing peanut butter yourself.

Disparities Still Exist

The good news? Peanut allergy rates are dropping. FARE reports a drop from 2.2% in 2015 to 1.6% in 2023 - that’s about 300,000 fewer children with peanut allergy in the U.S.

But not everyone is benefiting equally. A 2023 study found Black and Hispanic infants were 22% less likely to get early peanut introduction than White infants. That’s not just a gap - it’s a health inequity. It’s why public health efforts now focus on reaching families who need it most: community clinics, WIC programs, culturally tailored materials.

What’s Next?

Researchers are still learning. The PRESTO trial, funded by NIAID, is testing whether giving peanut even earlier - at 3 months - works better. Other studies are looking at introducing multiple allergens at once: peanut, egg, milk, wheat. Early signs suggest it might protect against more than one allergy.

The goal isn’t just to prevent peanut allergy. It’s to change how we think about food allergies altogether. We used to see them as unavoidable. Now we know: for many kids, they’re preventable.

What You Can Do Today

If you have a baby under 12 months:

• Check if they have severe eczema or egg allergy. If yes - talk to your doctor now.
• If they have mild eczema - start peanut around 6 months at home.
• If they have no eczema or allergies - introduce peanut when you start solids.
• Use smooth peanut butter. Never whole peanuts, chunks, or crunchy.
• Give 2 teaspoons of peanut butter (or equivalent) three times a week.
• Keep going, even if they don’t seem to like it. Consistency matters.

It’s not about perfection. It’s about progress. Even if you start a little late - at 7 or 8 months - you’re still helping. But don’t wait until 12 months. The window is closing.

Peanut allergy isn’t a mystery anymore. We know how to stop it. Now we just need to do it - for every child, everywhere.