Mosquito bump
An intensely itchy red or white bump that usually disappears within a few hours. Sometimes a blister forms on the bite. Scratching causes small sores and itchy bumps that last longer.
Allergic
Medically reviewed by Dr. A.M. van Coevorden, dermatologist, on
± 7 min read
Insect bitesan itchy bump after a bite or sting
An insect bite usually causes an itchy bump, redness or a dark spot that clears up by itself. Sometimes the bite becomes infected or you react allergically; then it needs assessing.
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- What is an insect bite?
- Why does a mosquito bite cause a bump?
- What does an insect bite look like?
- Normal reaction, infected or allergic?
- How does the dermatologist make the diagnosis?
- Treating an insect bite: what eases the itch?
- How long does an insect bite keep itching?
- What can you do yourself?
- When to see a dermatologist or GP?
- Frequently asked questions about insect bites
What is an insect bite?
Mosquitoes, bees, wasps, hornets, bumblebees, ticks, ants and horseflies bite or sting mainly in summer. Bed bugs and fleas can bite all year round. At the site of the bite or sting your skin reacts with an itchy bump, pain, redness or a dark spot. In most people this clears up by itself. Dermatologists call the normal reaction to a mosquito bite culicosis.
Why does a mosquito bite cause a bump?
The bump is your skin's reaction to substances the insect leaves behind when it bites or stings. With a bee or wasp that is venom, which hurts immediately. Some people, especially children, react more strongly: they get large swellings that last much longer than usual. This is called a persistent insect bite reaction. If you scratch the bump open, bacteria can enter the skin and the bite becomes infected.
What does an insect bite look like?
The location and pattern often tell you which insect bit you.
Bed bugs
Small red, itchy bumps, often in rows, on the legs, arms, neck and back: the skin covered by bedding. Mosquitoes bite exposed skin instead. The itch lasts about a week. Blood spots in the bed point to bed bugs.
Bee or wasp
A painful bump that turns red and can itch a lot. Without an allergy the swelling is gone within a few days.
Normal reaction, infected or allergic?
Three situations you want to tell apart.
Normal reaction
Itch, a bump, a red or dark spot and some pain. This clears up by itself, usually within a few hours to a week.
Infected insect bite
A few days after the bite the pain increases, the redness or dark spot keeps growing, or you get a fever and feel unwell. That fits a bacterial infection and needs assessment by a doctor.
Allergic reaction
Bumps all over the body, including the palms and soles, with intense itching and swollen eyes or lips. It becomes serious with difficulty breathing, a swollen tongue, stomach cramps, dizziness or fainting. This usually starts within fifteen minutes of a sting. Call 112.
How does the dermatologist make the diagnosis?
The dermatologist recognises an insect bite from the picture: the shape of the bumps, the place on the body and the pattern, such as rows with bed bugs. Your story helps: when the bump appeared, whether you were outdoors or slept in an unfamiliar bed. After a severe allergic reaction to a bee or wasp you are referred for allergy testing: a skin prick test and blood tests show which insect causes the allergy. At 247dermatologist you send photos of the bumps; within 12 to 48 hours the dermatologist assesses whether it is an ordinary bite, an infection or something else, such as hives or folliculitis.
Treating an insect bite: what eases the itch?
You treat an ordinary bite yourself. With infection or allergy, a doctor steps in.
Cool it
Hold ice wrapped in a cloth or a wet flannel on the spot for about 10 minutes. That reduces swelling and pain.
Remove a bee sting
Get the stinger out of the skin as fast as possible: scrape it away with a fingernail, tweezers or the edge of a bank card.
Soothe the itch
Levomenthol gel or zinc oxide lotion from the pharmacy helps against the itch. For a strong reaction, an antihistamine tablet from the pharmacy (cetirizine or loratadine) can calm the itch.
Through the doctor
For severe swelling the doctor may prescribe a corticosteroid cream for a short time. An infected bite needs antibiotics. For a persistent reaction that itches for months, the dermatologist assesses which treatment fits.
With a severe allergy
If you have a known severe allergy to bees or wasps, use your adrenaline auto-injector immediately and call 112. An allergist can treat the allergy with immunotherapy: injections of venom in increasing amounts so your body gets used to it.
How long does an insect bite keep itching?
The itch, the bump, the red or dark spot and the pain clear up by themselves, usually within a few hours to a week. Bed bug bites itch for about a week. A persistent insect bite reaction can keep itching for months. An infected bite heals after treatment with antibiotics.
What can you do yourself?
This is how you limit the damage:
- do not scratch: scratching causes sores that let bacteria into the skin
- cool the spot and use an anti-itch gel or lotion
- outdoors, use an insect repellent containing DEET against mosquitoes and ticks
- with bed bugs: wash all clothing and bedding at 60 degrees or hotter, seal cracks and call in a professional pest controller for a large infestation
- if you have a severe allergy: always carry your adrenaline auto-injector and tell people around you about your allergy
- with a bee or wasp allergy, avoid flowers, overripe fruit, perfume, bright clothing and bare feet outdoors
When to see a dermatologist or GP?
Please note
Call 112 for difficulty breathing, swollen lips or tongue, stomach pain, dizziness, fainting, or itching and a rash that spread quickly over the whole body after a sting. If you have an adrenaline auto-injector, use it straight away.
Call your GP immediately (or the out-of-hours GP service) if:
- you were stung in the mouth or throat
- you have a known severe allergy to insect stings
- you become short of breath or hoarse, feel dizzy or get severe stomach cramps
Make an appointment or have photos assessed if:
- the pain increases after a few days, the redness or dark spot grows, or you get a fever
- the bump or bumps do not clear up despite self-care
- you keep getting new bumps and do not know why
Not sure whether it is an insect bite or something else? Send photos of the bumps. A dermatologist at 247dermatologist assesses them within 12 to 48 hours, no referral needed, and writes a prescription where necessary.
Frequently asked questions about insect bites
Not sure whether this needs a look? Have a dermatologist assess it: you get an answer within 12 to 48 hours, no referral needed. In an emergency, contact your GP straight away or call 112.
How do I know if an insect bite is infected?
When, a few days after the bite, the pain increases, the redness or dark spot keeps growing, or you get a fever and feel unwell. That points to a bacterial infection. Have the spot assessed; antibiotics are usually needed.
What helps against the itch of a mosquito bite?
Cooling with ice in a cloth or a wet flannel, and a levomenthol gel or zinc oxide lotion from the pharmacy. For a strong reaction an antihistamine tablet can help. Do not scratch.
Why do I get such big mosquito bumps?
Some people, especially children, react more strongly to the insect's substances. They get large swellings that last longer. Unpleasant, but usually not dangerous. Bumps all over the body or shortness of breath do mean an allergic reaction.
How do I recognise bed bug bites?
Small red, itchy bumps in rows on the legs, arms, neck and back: the skin under the bedding. Blood spots in the bed are an extra clue. You only know for sure when you find the insects, in seams, cracks or behind wallpaper.
When is an insect bite an allergic reaction?
With bumps all over the body, swollen eyes or lips, and certainly with difficulty breathing, a swollen tongue, stomach cramps, dizziness or fainting, usually within fifteen minutes of the sting. Call 112.
How long does a mosquito bite keep itching?
Usually a few hours to a week. Bed bug bites itch for about a week. If a bump keeps itching for months, it may be a persistent insect bite reaction.
Can I scratch an insect bite open?
Better not. Scratching creates sores that let bacteria in, and then the bite gets infected. Cool the spot and use an anti-itch gel.
Have a dermatologist look at your skin
Upload photos and answer a few questions. A BIG-registered dermatologist replies within 12 to 48 hours, no referral needed, from € 39.
If more is needed, the dermatologist refers you to a medical specialist.
Want to know what a dermatologist does, when you can see one and how quickly that can happen? Read more about the dermatologist.
Sources and more information
- Ik ben gestoken door een insect, wat nu? (thuisarts.nl)
- Insecten steken, muggenbeten (culicosis) (huidziekten.nl)
- Insectenbeten en persisterende insectenbeetreacties (huidziekten.nl)
- Bed bugs, patient leaflet (huidziekten.nl)
- Bee and wasp stings, patient leaflet (huidziekten.nl)
Source: Thuisarts.nl (NHG) and huidziekten.nl.
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