"Allergenic" means something that can cause an allergic reaction in some people. It refers to substances or things that may trigger allergies for individuals who are sensitive to them. Full definition
Additionally, delaying the introduction of highly allergenic foods such as peanuts, tree nuts, and seafood until after the age of 3 years may help prevent allergy to these foods. (verywell.com)
Peanut allergy develops early in life and is rarely outgrown.7 - 9 Clinical practice guidelines from the United Kingdom in 19989 and from the United States in 200010 recommended the exclusion of allergenic foods from the diets of infants at high risk for allergy and from the diets of their mothers during pregnancy and lactation. (nejm.org)
In most cases, you don't even have to wait to introduce highly allergenic foods like eggs, fish, and peanuts. (babycenter.com)