Why do mosquito bites itch?

“I was outside for a few minutes and now I have this red, itchy bump that won’t stop bothering me. Why do mosquito bites itch and sometimes swell up more than usual?”

Daisy Oliveira
Registered Nurse CNO #13564387

When a female mosquito bites you, she injects a small amount of saliva into your skin to keep your blood from clotting while she feeds. Your immune system identifies the proteins in this saliva as foreign invaders and releases a chemical called histamine to fight them off. This natural immune response is what causes the classic red bump and that familiar, persistent itch.

The itching and swelling usually appear within minutes and can last for several days. While most reactions are mild, some people experience more intense swelling or heat at the bite site, often referred to as skeeter syndrome. It is important to remember that mosquitoes can also carry various diseases, so you should monitor your symptoms closely.

To manage the discomfort, you can use over-the-counter antihistamines or topical creams, but avoid scratching the area as this can lead to an infection. Using insect repellent and wearing long sleeves are the best ways to prevent bites when you are outdoors. If you notice a fever or a rash that spreads quickly, you should consult a doctor or a dermatologist for a professional evaluation.

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