Recent research has shown that children are less likely to develop peanut allergies if they are exposed to peanut as an infant. The best age to start peanut-containing foods depends on whether the child has eczema or other food allergies. Infants with severe eczema and/or other food allergies benefit the most if they have peanut between 4 and 6 months of age. These infants are also at the highest risk for allergic reaction, however, and may need allergy testing before they try peanut. Babies with mild eczema should be offered peanut-containing foods around 6 months old. Babies without eczema and without food allergies are at low risk of developing peanut allergy, so timing of introduction is less critical; it's fine to introduce peanut-containing foods anytime after 4 months of age.
Once you've determined with your doctor that your baby is ready to try peanut, click here* for instructions on how to feed peanut-containing purees safely, signs of allergic reaction, and recipes for purees with a good amount of peanut protein. Offering one of these purees 3 times in a week is considered an adequate exposure to peanut.
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* Source: National Institute of Allergy and Infectious Diseases