My kid had a wasp sting 9 days ago. last night it got itchy and he got hives in the same spot again. does this need to be treated?

What the evidence says

What your son has sounds like a large local reaction, a swollen, itchy patch that forms around a sting site. The Canadian Paediatric Society explains that these local reactions usually grow for a day or two and then take three to ten days to fully settle, and some studies of insect stings have found local swelling can last anywhere from one to three weeks. So itching and hives at day nine, right at the old sting site, still fits inside a normal, if slow, healing pattern.

This type of reaction is different from anaphylaxis, which is a whole-body allergic emergency. Canadian guidance is clear that a large local reaction, even a big or itchy one, does not need epinephrine, an epinephrine auto-injector, or a referral for allergy shots, because on its own it does not predict a dangerous reaction to a future sting.

For treatment, the same Canadian guideline says a cold compress, a non-drowsy oral antihistamine, and plain pain relief if needed are the usual steps. If the swelling is unusually large or uncomfortable, a doctor might add a short course of an oral steroid, but that is only needed for more severe cases.

There is a rarer pattern worth knowing about too: some children develop a delayed, serum-sickness-like reaction one to two weeks after a sting, with hives, swollen lymph nodes, and sometimes joint aches, again usually just from skin studies, not big trials. If your son develops swollen glands, joint pain, fever, or hives spreading well beyond the sting site, it is worth a call to his doctor.

Any sign of a whole-body reaction, hives all over, swelling of the face, lips, or throat, trouble breathing, vomiting, or dizziness, is different and needs urgent medical attention right away, even though that was not the case here based on what you described.