Mosquito Bites: Is There a Problem?

[Jujubee]

We have a friend who unfortunately got stung by some mosquitoes right in his room two nights ago while his window was kept open. I also got some "bites" from them. Strangely, all of the areas where he was stung still swelled, hot, red and speaded around a little, whereas all of ours have become milder and some have disappeared already.
He tells us that it is actually normal and those red bites will go away soon tomorrow, because it has always been late like that since he was born.
Do you think his blood has some problem that needs to be checked out at once ?

thanks a lot in advance

 

[Moonbear]

He's probably just allergic to the bites. When a mosquito bites, they "inject" an anti-coagulant to facilitate drinking your blood, which is the cause of the itching you'll feel after getting bitten. I suppose if someone were especially allergic to the protein that acts as the anticoagulant, they might have more persistent swelling or itching at the site of a bite.

 

[Jujubee]

Thank you,
But is it good or bad anyway ?