Sugar. Usually in the form of caramel, chocolate, and high fructose corn syrup.
Sugar
a main dish is a main dish & sweets are sweets
Sugar is the source and main ingredient for all sweetend foods like chocolates, Sweets, biscuits and other sugar cookies
The shake's main ingredient is milk.
The main ingredient in yoghurt is milk.
Flour ( pasta ) is the main ingredient
Sausage is the main ingredient.
Beijing food does not have a main ingredient. Anything could be the main ingredient. It depend on the food.
Sugar is the main ingredient of candy
Cabbage is the main ingredient in sauerkraut.
Main ingredient is starch
The main ingredient in ham salad is ham.
That is an unusual reaction to sweets, and I don't think that it is the sugar which is doing it, I think that you are eating sweets that contain some other ingredient, perhaps a kind of fruit, to which you are mildly allergic.