I am breastfeeding a 7 months old baby with lots of food allergies e.g. egg, milk, wheat and corn. How long do these allergens stay in my breast milk?

Breast milk. Many pediatricians and pediatiric clinics assign the diagnosis of "foor allergies" as a cause of "colic" or poor feeding by an infant. It is possible that no "true allergies" have occurred, and if your infant is thriving (putting on predicted weight) it is unlikely that your breast milk is creating a problem. Ask a pediatric dermatologist for advice if your infant is not growing appropriately.

Related Questions

How long can a baby thrive on just breast milk? Dr is pushing to start solids at 6 months but I want to wait until 10-12 months due to food allergies.

Solid Foods. The recommended time to startbsolid foods is 4-6 months of agr. This doesn't mean you have to stop breastfeeding. In fact you are encouraged to continue. But this is the time to add solids.
No rush. The push to feed solids is cultural & became popular in the 50's when mom's didn't breastfeed & made their own formula. Docs pushed solids to make up for its poor nutritional balance. Many cultures breast feed only until well past a year & their kids go directly to table foods. It is fine for you to. That said, avoiding the solids may just delay the appearance of food allergies, not stop them.