22nd August, 20218 min read

When to see a doctor about an infected insect bite

Medical reviewer:
Dr Adiele Hoffman
Dr Adiele Hoffman
Dr Ann Nainan
Dr Ann Nainan
Last reviewed: 13/08/2021
Medically reviewed

All of Healthily's articles undergo medical safety checks to verify that the information is medically safe. View more details in our safety page, or read our editorial policy.

What is an infected insect bite?

Sometimes, when you’re bitten or stung by an insect, the wound can become infected. This is because bacteria can get into the break in your skin caused by a bite or sting, and then cause an infection. Or you may scratch an itchy bug bite and damage your skin, which can also allow bacteria from your hands to infect your skin.

Insect bites are usually harmless and your skin gets better by itself within a few days. But if your skin gets infected, the bite or sting may hurt more, swell up a lot and become very red.

Skin infections aren’t the only type of infection you can get from an insect bite. Some, like tick or mosquito bites, can lead to a serious internal infection like Lyme disease or malaria.

If you think you have an infected insect bite or symptoms of any disease like Lyme disease or malaria, see a doctor immediately.

When to see a doctor about an infected insect bite

Call an ambulance or go to the emergency department immediately if you have painful, hot and swollen skin and:

  • a high temperature
  • feel hot and shivery
  • your heart is racing
  • you’re breathing fast
  • it has purple patches on it
  • you feel dizzy or very unwell
  • you feel confused or faint
  • you look pale, feel cold and clammy, or your body has lost its normal colour
  • your nose or gums are bleeding
  • you’re vomiting blood or see blood in your poo
  • bad tummy pain

Sometimes, an insect bite can cause a severe allergic reaction called anaphylaxis. Call an ambulance immediately if you have symptoms of anaphylaxis, including trouble breathing, dizziness, and face, mouth, lips, tongue, throat and airways swelling.

See a doctor if you have an infected bite or sting and your symptoms are getting worse or aren’t getting better. This includes if the bite or the skin around it:

  • is getting more painful, red and hot
  • is swelling up more
  • is producing pus
  • has turned into a big circular rash that looks like a ‘bull’s eye’ on a dartboard

See a doctor as soon as possible too if you’ve been bitten recently and:

  • are vomiting
  • have a fever
  • have a bad headache
  • feel dizzy or faint
  • are shivering
  • have muscle, joint pains or body aches
  • feel very tired and don’t have any energy (fatigue)

What are the symptoms of an infected bite?

It’s common to have a mild reaction like redness, itchiness and some swelling shortly after an insect bite or sting, but it’s rare for a bite to cause a skin infection.

Even though it’s uncommon, an infected bite is still possible, especially if:

  • your symptoms get worse over time
  • the skin near or around the bite is sore, hot and swollen – your skin will usually be red, but if you have darker skin it may be less obvious
  • the area of affected skin around the bite or sting getting bigger
  • there’s pus in the bite or sting
  • you have a high temperature (fever) or feeling warm, chills and a headache
  • you have swollen, painful glands
  • you have red sores or blisters
  • you have a red or dark line or streak that runs from the bite or sting
  • you have a circular rash

You’re more at risk of getting a skin infection from a bite if you:

  • have had skin infections before
  • have a condition causing fluid build-up under your skin like lymphoedema
  • inject drugs into your body
  • have poor circulation in your arms and legs because of other conditions like obesity
  • have a weakened immune system
  • have diabetes

Read more about the different types of insect bites, including flea bites.

Infected insect bite can cause cellulitis

What kinds of infections are caused by insect bites?

An insect bite can cause skin infections such as:

Serious parasitic and bacterial infections you can get from being bitten by an insect include malaria and dengue (spread by mosquitoes in certain parts of the world) and Lyme disease (spread by some ticks, in places like the UK).

Read more about the symptoms of malaria, dengue and Lyme disease.

Tick bites can lead to an infection like Lyme disease, which may cause a big circular rash on your skin that looks like a ‘bull’s eye’ on a dartboard

What’s the treatment for infected insect bites?

If a doctor thinks you have a skin infection, you may need antibiotics. This could be antibiotic tablets or creams. It’s important to keep a close eye on your infection, which should start to get better after about 2 days. But always finish the course of antibiotics even if you start feeling better, as this will make sure the infection clears up completely.

If your infection isn’t getting better after a few days, see a doctor again. Sometimes, if your infection is serious, you may need to go to hospital to get antibiotics given by vein, or intravenously (IV).

Most infected insect bites clear up within 10 days. But if the infection has spread over a large area of your body or you have other health problems like diabetes, for example, you may get complications and need to be treated for longer.

If you’ve got Lyme disease, you’ll usually need to take antibiotics – you may need to take them for a few weeks, depending on your symptoms. Read more about the treatment for Lyme disease.

If you have malaria, you’ll usually be treated with antimalarial drugs, which also prevent malaria.

There’s no specific treatment for dengue, so it’s about managing your symptoms until the infection has gone. This includes staying hydrated and taking painkillers like paracetamol to relieve your pain and fever – speak to a pharmacist about how to safely get and use these medicines. But don’t take ibuprofen or aspirin, as these medicines may cause bleeding problems. Sometimes dengue can cause a severe infection which can be life-threatening and needs treatment in hospital.

Read more about the treatment for malaria and dengue.

If you have a skin infection from an insect bite, try these self-care measures:

  • take painkillers to help with any pain you’re in – but first speak to a pharmacist about how to safely get and use these medicines
  • raise the part of the body that’s swollen to help bring down the swelling
  • keep moving the joint near the infected insect bite, like your ankle, to stop it from getting stiff
  • stay hydrated by drinking enough water
  • keep your skin clean and use antiseptic cream
  • check if the infected area is getting worse by drawing a circle around it with a pen and checking the area regularly to see if the redness or swelling is spreading past the circle

How to prevent an insect bite from getting infected

The best way to stop insect bite infections is to avoid getting insect bites in the first place. You can do this by covering up as much of your skin as possible when you’re outside, using insect repellent and safely removing ticks, for example. Read more about the best treatment for insect bites and how to get rid of bedbugs.

If you do get bitten or stung, don’t scratch or touch the insect bite or sting as this could cause an infection.

The best way to stop an insect bite infection is to avoid getting bitten, so try insect repellent when you're outdoors.

Your health questions answered

Why do my insect bites always get infected?

Anyone can get an infected insect bite. If your body can’t get rid of bacteria when it gets into your wound, you can get an infection. And if you have a condition like diabetes, eczema or obesity – or you’ve had an insect bite infection before – you’re more likely to get an infected insect bite or sting. These conditions affect your immune system badly and so your body can’t fight off infections.

Key takeaways

  • if you have an infected insect bite or sting, your skin may become more painful, swollen and red
  • insect bites can cause different skin infections like impetigo, cellulitis and lymphangitis
  • you can also get serious infections from ticks and mosquitoes like Lyme disease and malaria
  • it’s better to see a doctor if you’re worried or have symptoms of an infection, as you may need antibiotics
  • call an ambulance if you have symptoms of a severe allergic reaction (anaphylaxis), including finding it hard to talk, trouble breathing, dizziness, or your mouth, face or throat swelling up
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