Insect bites and stings - Complications 

Complications of insect bites and stings 

A number of complications can develop after being bitten or stung by an insect.


Secondary bacterial infections are a common complication of insect bites and stings. They include:

  • impetigo – a highly contagious bacterial infection that causes sores or blisters
  • cellulitis – an infection that makes your skin red, swollen and painful
  • folliculitis – inflammation of one or more hair follicles (the small holes in your skin that hair grows out of)  
  • lymphangitis – an infection that causes red streaks in your armpit or groin and swollen lymph nodes (small glands that are part of the immune system) 

An infection can occur if you scratch an insect bite or sting, or it may be introduced at the time you're bitten.

Infections are usually treated with antibiotics.

Lyme disease

Lyme disease is an infection caused by a species of tick known as Ixodes ricinus. Ticks aren't insects – they're small arachnids.

There are an estimated 2,000-3,000 cases of Lyme disease in England and Wales each year, with about 15 to 20% of cases occurring while people are abroad.

Your risk of developing Lyme disease is increased if you spend a lot of time in woodland or heath areas as these areas are where tick-carrying animals, such as deer and mice, live.

The initial infection is characterised by a red rash that gradually expands outwards from the site of the bite. Antibiotics are usually used to treat the infection.

If untreated, the long-term effects of Lyme disease include problems with the nervous system, such as:

  • meningitis – an infection of the protective membranes that surround the brain and spinal cord
  • facial palsy – weakness of the facial muscles that causes drooping of one or both sides of the face
  • encephalitis – an uncommon but serious condition that causes inflammation of the brain

The condition can also damage the joints, which can lead to arthritis and, occasionally, heart problems, such as inflammation of the heart muscle (myocarditis) and inflammation of the fluid-filled sac that surrounds the heart (pericarditis).

West Nile virus

West Nile virus is an infection with flu-like symptoms that is spread by mosquitoes. 

There have been no reported cases of West Nile virus in the UK, but there have been cases elsewhere in the world. 


Malaria is a tropical disease caused by an infection of the red blood cells. It can be transmitted to humans by the bite of an infected mosquito.

Each year, there are around 1,500 cases of malaria in travellers returning to the UK. A certain type of malaria caused by the parasite Plasmodium falciparum is potentially fatal. It accounts for more than half of all cases of malaria in the UK each year.

Page last reviewed: 27/06/2014

Next review due: 27/06/2016


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The 3 comments posted are personal views. Any information they give has not been checked and may not be accurate.

Anya311 said on 16 August 2012

I noticed pain in my finger at a wedding in Somerset on July 5 2012 (now 16/08/12) and when returning home I visited the hospital as my finger was really painful and the joint above my ring was swollen and red. I was told it was an insect bite with "scissor" teeth, as it was a little gash, and not a hole. Three subsequent visits to hospital, one to have my ring cut off, two courses of anti-bitotics, an X-ray, now a course of strong antihistamines, and my finger is still really painful and the joint distorted.

I have had other bites which resulted in great swelling (three times on my other hand), itchyness and redness, but they went away after about a week.

When my ring was cut off, the redness and swelling spread to my hand, but it is just my finger now. I have been told to "rest it". It is my right hand and despite elevation, ice etc, it is not getting better.

I have other more recent bites, but I feel they will go away in a few days. Does anyone have a similar experience please? My doctors are very helpful, but are at a loss as to any further treatment, other than time. It has been 42 days now.

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judidw said on 27 July 2012

I was bitten by something on the 25 July 2012 as well. it seems in the same place. My ankle has swollen to the point that the skin feels like it is going to burst. Tried to see my GP yesterday afternoon as I was in pain and could not walk, but there was no one on duty! The Chemist gave me Cetirizine too but they have done nothing except given me dry mouth. I am at the end of my tether with this.

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digerd said on 25 July 2012

Biting insects have always liked me, and people with me have not been bitten, they just make a bee line for me

Hot weather at beginning of dusk is when I must be indoors!!

On 23rd July 2012 at 9'15 pm I was suddenly attacked by several, but the ones that bit my right ankle caused cellulitis, which had not happened before in my life
I saw the nurse at GPs who diagnosed cellulitus and prescribed antihistamine - Cetirizine-10mg once a day and Antibiotic Ciproloxacin 500mg twice a day
Next day it got worse and the hard swelling of the ankle spread up the whole shin to calf muscle by 2pm on Wednesday
The ankle stops me from walking as will not bend much as skin so tight, but today's advice is to wait until the morning and if crept up into thigh, or ankle skin has split open, I must go to A&E
At the rate of it spreading up my leg farther, I fear I may be there before the morning and will need intravenous antibiotics, which I have never had before and is all very worrying

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Lyme disease

Lyme disease is a bacterial infection spread to humans by infected ticks. Find out how to avoid being bitten and what to do if you are