Hives 4 Yr Old Son

Have your doctor/Pediatrician test him for food allergies/intolerances (and if he/she won't, take him to a naturopathic doctor). A food intolerance/allergy can make you break out in hives. I can't eat anything with mint oil (the real stuff, not something that's been made/fabricated)--peppermint oil, spearmint oil, creme de menthe, wintergreen oil, etc. I break out in huge hives all over my body.

I also have what's called cold-induced hives. It can be from cold weather, working outside in the cold, taking a cold shower in the summer, being outside where it's cold and coming indoors where it's warm--I break out in hives. Unlike a food intolerance/allergy--where you can avoid the food--there's nothing that can be done for this.

Good luck.

I will get hives if I am too stressed.
My son got them when he was about 4, I gave him benedryl and instead of it helping the hives or making him sleepy he got really hyper, bouncing off the walls. My oldest daughter, 20 at the time, came over and stayed at the house with us to help me with him. Nothing worked. She was talking to her boyfriend and his Mom had gotten hives many years before and had gone from doctor to doctor to doctor seeking relief. At a doctor's office she happened to sit next to a woman who told her to put Crisco (liquid) on the hives and they would go away. It worked. I didn't have Crisco but had olive oil and we poured some in a bowl and put it on his hives and watched them disappear. I don't know why it worked but it did.
The big caution with hives is they can appear in the throat and are then called anaphylactic shock and can swell and close off his air way. Watch his breathing and be sure he is breathing okay. If he starts to have difficulty breathing call 911, don't drive him to the ER yourself. The ambulance will have oxygen, you probably don't.
Often you don't find the cause of hives. It may have been a reaction to the antibiotics or any one of a number of things.
It's not my intent to scare you I hope I didn't, just want to be sure you understand how bad it can get. Luckily most of the time it doesn't get that bad.

You can actually get hives as a reaction to a virus. It happened to my son at about the same age--I think he was 5. He had such horrible hives all over that they had to put him on predinisone. Turns out it was a reaction to a virus. Hasn't happened since and he's 11 although he did have seasonal allergies last Spring.

Sometimes hives can be a reaction to a virus or other infection. When my son was younger, he had very reactive skin, sometimes would break out in hives with a cold, and for no other discernible reason. Skin is weird. You might never know what triggered the hives. Keep an eye on it, and if it happens repeatedly, he is old enough for an allergy test, it might be worth while. But as long as it stays an isolated skin reaction (not over his entire body, and not progressing to respiratory symptoms) it's irritating (no pun intended) but not something to worry too much about.

I suggest seeing a pediatric allergist instead og your regular ped for anything allergy related. My youngest actually breaks out in hives if he does not get zyrtec daily but he tests negative for everything. My oldest gets hives every time he gets sick whether it's viral or bacterial it's just his immune systems response.

Have you switched laundry detergent or soap? Maybe something in his room is bothering him. Is it duster in the new home? Rent a carpet cleaner and clean all the rugs in your home.