In order to make earrings this way the posts must be made with certain metals. Nickel is good but high carat gold is better. Some people can tolerate surgical steel and some may be able to wear sterling silver as a post or wire to stop the allergice reactions they might have.
You turn normal earrings into hypoallergenic earrings. Hypoallergenic quality depends on the material of the earrings like earrings made of 14-karat gold, nickel-free stainless steel, or sterling silver.