OP here. We eliminated the mandarin oranges and then reintroduced them - immediate flush.

I have no clue why since he eats other citrus fruit and these are just the organic mandarin oranges in juice. Weird...

Anything acidic turns my son's cheek's pink, even cut up peppers.

It could be the acid in the fruit. Wash his face as soon as possible after he eats citrus.

Both of my kids had that from strawberries and oranges, both are now adults with no food allergies.

My irish/pink skinned son always has red cheeks because they're chapped a little in the winter. He now wears coconut oil to bed on his cheeks and it has gotten better

Is your toddler teething? Or sleeping on one side of their face?

How fair skinned is your child? If he gets red cheeks after being outside on a really windy day, that’s a sign that he’s just got very sensitive skin. Children who are extremely fair can have these kinds of reactions to acid food even if they aren’t allergic; their skin is just so pale and sensitive that it shows everything. My very pale children used to look red and splotchy if they cried hard when they were toddlers. If they ate ketchup with their food and any of the ketchup got on their cheeks, the skin that the ketchup touched would stay bright red for a little bit after they ate. They’re in middle school now and do not have any food allergies.

The red cheeks showed up on my daughter as soon as we tried regular milk after having her on goat’s milk before that. It’s a common allergy sign. Talk to your allergist.

Does he get the flashing around his mouth? My daughter gets splotchy red marks when she doesn’t wipe her mouth well after eating strawberries. I think the acid from fruits can do that to skin. But I would presume it would be more around his mouth if yes.

Otherwise, is he teething his two-year molars? My daughter gets red cheeks when she is teething, it’s almost always a sure sign for us to check her mouth.

DS, 26 months, get occasional flushed cheeks. It isn’t a rash and it doesn’t bother him at all. The only thing I can think of that seems to be related is that he gets the flushed cheeks after eating fruit salad with the only new food being mandarin oranges and orange juice (to stop apples from browning). He’s never had any kind of a reaction to citrus before.

Is it possible to not have a problem with citrus fruit but have a small reaction to canned mandarin oranges?