Why You Need to Stop Scratching Those Mosquito Bites, According to a Derm

Woman looking at palm trees

If you were to look at my legs, you’d notice they’re speckled with scars. You’d have to examine them closely — most are the diameter of a pencil eraser — but they’re there nonetheless. I blame most of these markings on mosquito bites . . . and, I suppose, my inability to resist scratching those infuriatingly itchy lumps into scabs (which eventually turn to brown spots).

The question of how to make mosquito bites stop itching is age old. It’s one of the reasons why mosquitoes are so deeply unpopular among humans. But, let’s imagine for a moment that these little creatures are merely doing what they must to survive (yes, there is a reason they bite). Below, the buzz on why mosquitoes bite, why mosquito bites itch, and what we can all do to soothe those bites — before scratching them into oblivion and leaving scars in their wake.

Why do mosquitoes bite?

Interestingly, human blood contains necessary nutrients (specifically, proteins) for egg laying; ergo, only female mosquitoes bite. 

Mosquitoes are lured by numerous factors — some of which are still too complex even for scientists to decipher. One of the most salient and agreed-upon attractors, though, is carbon dioxide — which is unfortunate for humans, who emit CO₂ through their skin and with every exhale. To make matters trickier, mosquitos can detect CO₂ emissions from up to 115 feet away (you can run, but you can’t hide!). Many researchers theorize that larger people tend to get more bites because they have more surface area and emit more CO₂. 

And, you might want to steer clear of exercising in a mosquito-ridden area. Lactic acid (which our bodies produce as we work out) and increased body heat are both instigators for a mosquito bite. When we sweat, the smell itself also seems to be another attractant, though why mosquitoes enjoy your post-run musk is still somewhat unclear. 

If you’re a couch potato who rarely perspires, you’re probably still wondering: why do mosquitoes deem me as a tasty snack!? Your blood type might just provide some answers. A study published in the Journal of Medical Entomology found that, among 64 participants, mosquitoes were significantly more attracted to people with O blood types than others. When released to groups of people separated by blood type, a whopping 83 percent of mosquitoes landed on those with O blood types versus 47 percent of mosquitoes slurping on subjects with A blood types. (I imagine this study is akin to putting humans in a room with pizza and kombucha.)

Why do mosquito bites itch?

When a mosquito pierces the skin to suck your blood, she also deposits her saliva. (Imagine sipping from a straw — despite the sucking motion, inevitably you’ll still leave some spit behind.) Mosquito spit contains proteins that our bodies don’t recognize. As a result, our immune systems interpret the skeeter spit as an unwelcome intruder. 

Once our internal alarm bells sound, our immune system releases histamines — chemical compounds responsible for our body’s allergic inflammatory response. Cue redness, itchiness, and various other signs of a blossoming allergic reaction. 

So, yes — most humans are, essentially, allergic to mosquito bites. And, just as the severity for other allergies can range, some people react more dramatically to those bites. According to Rachel Pritzker, MD, a Chicago-based board-certified dermatologist, “It has to do with your histamine release — or how hard your body reacts to fight the bite.” Some people’s bodies fight vigorously and overreact. The result: welts and extreme redness.

How to calm a mosquito bite

Once you’ve been bitten, it’s best to don a pair of mittens and sit on your hands. But, our modern world prohibits such idleness, so there are some alternate solutions to soothe a mosquito bite. 

Most importantly, don’t start scratching. “Just like an acne bump, these lesions are very inflammatory from the start,” Dr. Pritzker notes. “If you pick, you are increasing the inflammation and risking a scar, which could be permanent.” (Case in point: My dotted legs.)

Of course, once you start scratching, it’s difficult to stop. In these cases, Dr. Pritzker recommends applying an over-the-counter steroid cream. “Hydrocortisone can help with the itch and reduce the inflammation faster,” she says, “hopefully preventing a scar.” If you’re particularly reactive to mosquito bites, Dr. Pritzker advises asking your dermatologist for a stronger prescription cream to have on hand.     

[Editor’s note: As always, talk to your doctor before starting or stopping any new treatment.]

How to prevent mosquito bites 

If you want to avoid mosquito bites in the first place, spritz on some repellent. DEET, or diethyl-meta-toluamide, is a tried-and-true option contained in many commercial mosquito repellants. The ingredient has stirred up some controversy in the past due to potential health concerns, but according to the CDC, it should not be harmful when used as directed. Safety aside, DEET has a distinct, pungent odor that’s arguably just as effective for repelling your fellow humans as it is repelling insects.

If you prefer spending time in the great outdoors without smelling like a camper, consider a fragranced repellent like Kinfield Golden HourTM ($22), which contains citronella with hints of vanilla and clove. Interestingly, fragrance fans swear that Victoria’s Secret Bombshell® ($25) effectively repels the little bloodsuckers — and science has since backed these claims. 

Now that I’m armed with mosquito knowledge, I’m hopeful that my constellation of skeeter scars is part of a finite universe — one that I can control with perfume, lounging indoors, and a touch of hydrocortisone as needed. 

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