There are a couple of different reasons why your mosquito bite may be extremely big, or at least bigger than normal. The first is that you may be experiencing a more severe allergic reaction to the saliva injected by that specific mosquito.
Some people have hardly any allergic reaction at all, while other people experience enormous mosquito bites that can severely affect quality of life. There are hundreds of different species of mosquito, each one having its own chemical signature in the saliva that it injects into your skin, causing a mosquito bite. You may be more allergic to one type of mosquito that another.
In extreme cases, mosquito bites can cause an allergic reaction so severe that it can become life-threatening or even fatal. In some unlucky people, mosquito bites can grow to fantastic sizes and become large welts which take many days to dissipate and heal.
Another reason for having a very large mosquito bite, which is very common, is that it is not actually a mosquito bite at all, but has been misidentified as such. The reason for this is that many different types of insect bites look extremely similar to a mosquito bite, and it can be difficult for even doctors and professionals to determine the difference. You may have been bitten by another insect such as a spider, which has a much more powerful venom that it injects into the skin, causing a much larger bite mark.
If you have what seems to be an unusual and severe reaction to mosquito bites, in which the bites grow to alarmingly large proportions, you should seek medical advice as there are medications that can help to reduce the suffering that you are experiencing.
