Stings, insect
Introduction
Many insects sting as a defence by injecting venom into your skin. A sting often causes a swollen, red mark to form on the skin. This can be itchy and painful, but is harmless in most cases.
The affected area will usually remain painful and itchy for a few days. The mark left on the skin after an insect sting is known as a weal.
Sting or bite?
In the UK, stinging insects include:
Some other insects bite, including as mosquitoes, fleas, bedbugs and ticks. Read more about insect bites.
Allergic reactions to insect stings
Some people have an allergic reaction after a sting. This can cause symptoms that vary in severity, from pain and swelling to a potentially life-threatening allergic reaction that will require immediate medical attention (anaphylaxis). Anaphylaxis after an insect sting is rare.
Read more about the symptoms of an insect sting.
When to seek medical help
Seek emergency treatment if you have any of the following symptoms immediately after being stung:
- swelling or itching anywhere else on your body
- a skin reaction anywhere else, particularly pale or flushed (red or blotchy) skin
- wheezing or difficulty breathing
- a headache
- nausea, vomiting or diarrhoea
- a fast heart rate
- dizziness or feeling faint
- difficulty swallowing (dysphagia)
- confusion, anxiety or agitation
Call 999 and ask for an ambulance, because this type of reaction can be fatal.
Treating insect stings
If you are stung by a bee, it will leave its sting and a venomous sac in the wound. You should remove this immediately by scraping it out using something with a hard edge, such as a bank card.
Do not pinch the sting out with your fingers or tweezers because you may spread the venom.
To treat an insect sting, after you have removed the sting if you were stung by a bee:
- wash the affected area with soap and water
- put a cold flannel on the area
- raise the part of your body that has been stung to prevent swelling
- avoid scratching the area because it may become infected
If the sting is painful or swollen, you can also:
- place an ice pack on the area (try a bag of frozen peas or some ice wrapped in a towel)
- take painkillers, such as paracetamol or ibuprofen
- use a spray or cream containing local anaesthetic, antihistamine or mild hydrocortisone (1%) (available at pharmacies) on the affected area to prevent itching
- take an antihistamine tablet (available on prescription or from pharmacies) to help reduce swelling
If the redness and itching get worse or do not clear up after a few days, see your GP.
Read more about treating insect stings.
Preventing insect stings
You can avoid being stung by an insect by:
- using insect repellent
- wearing long-sleeved shirts and trousers outdoors
- not disturbing an insect’s nest
- avoiding areas where there are likely to be lots of insects, such as clusters of flowers and piles of wood
- moving away slowly without panicking if you encounter wasps, hornets or bees (do not wave your arms around or swat at them)
If you think you are allergic to insect stings, your GP will refer you to a specialist allergy clinic and may prescribe a syringe (called an auto-injector) loaded with adrenaline, including instructions on how to use it. Some people with allergies carry a card or wear a medical alert bracelet or necklace.
Read more about preventing insect stings.
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Symptoms
If you are stung by an insect, such as a wasp, the area around the sting will become swollen, go red and a raised mark will form. The raised mark is called a weal.
Some people may have further symptoms after an insect sting, although most people will not have severe symptoms. The reaction can be classed as:
- a minor localised reaction – this is normal and does not require allergy testing, although the affected area will often be painful for a few days
- a large localised reaction (LLR) – this can cause other symptoms such as swelling, itching and a rash
- a systemic reaction (SR) – this often requires immediate medical attention as it can cause a potentially life-threatening allergic reaction (anaphylaxis)
An allergic reaction occurs when the venom from the sting triggers the release of chemicals in the body, such as histamine. The chemicals can affect the blood vessels in two ways:
- they can widen, causing a drop in blood pressure
- they can leak, causing swelling, particularly in the mouth and on other parts of the skin
People who have a systemic reaction (SR) due to an insect sting may experience much more severe symptoms and will need to be referred to an allergy specialist for testing and treatment. However, although insect stings are a common cause of anaphylaxis, it is rare to experience anaphylaxis after an insect sting, and it is rarely fatal.
Large localised reactions and systemic reactions are described in more detail below.
Large localised reaction (LLR)
If you have a large localised reaction (LLR) after being stung by an insect, a large area around the sting will swell up. The area may measure up to 30cm (12in) across, or your entire arm or leg could swell up.
The swelling will usually last longer than 48 hours but should start to go down after a few days. The sting will be painful but the swelling will not be dangerous unless it affects your airways.
If you are stung many times by one or more insects, your symptoms will be more severe because a larger amount of venom will have been injected.
You may have an LLR several hours after being stung. This could include:
- a rash
- nausea
- painful or swollen joints
Systemic reaction (SR)
A systemic reaction (SR) is often less severe in children than in adults, and children are less often referred for venom immunotherapy (see treating stings for more information). It is rare for an SR to be fatal, especially in children, although someone with an existing heart or breathing problem is at increased risk.
It is also more likely that someone will have an SR if they have been stung before (sensitised), especially if it was recently. People who have been sensitised to bee stings are more likely to have an SR than people who are stung by wasps.
If you have any of the following symptoms immediately after being stung, seek emergency treatment. Call 999 and ask for an ambulance immediately as this kind of reaction can be fatal:
- swelling or itching anywhere else on your body
- a skin reaction anywhere else, particularly pale or flushed (red or blotchy) skin
- wheezing, hoarseness or difficulty breathing
- a headache
- nausea, vomiting or diarrhoea
- a fast heart rate
- dizziness or feeling faint
- difficulty swallowing (dysphagia)
- a swollen face or mouth
- confusion, anxiety or agitation
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Treatment
As soon as you have been stung by an insect, remove the sting and the venomous sac if it has been left in the skin. Do this by scraping it out, either with your fingernails or using something with a hard edge, such as a bank card.
When removing the sting, be careful not to spread the venom further under your skin and do not puncture the venomous sac.
Do not pinch the sting out with your fingers or a pair of tweezers because you may spread the venom. If a child has been stung, an adult should remove the sting.
Wasps and hornets do not usually leave the sting behind, so could sting you again. If you have been stung and the wasp or hornet is still in the area, walk away calmly to avoid being stung again.
Basic treatment
To treat insect stings:
- Wash the affected area with soap and water.
- Put a cold flannel on the area.
- Raise the part of the body that has been stung to prevent swelling.
- Avoid scratching the area because it may become infected (keep children’s fingernails short and clean).
See your GP if the redness and itching gets worse or does not clear up after a few days.
Additional treatment
If the sting is painful or swollen, you can also:
- Wrap an ice pack (such as a bag of frozen peas) in a towel and place it on the swelling.
- Take painkillers, such as paracetamol or ibuprofen (children under 16 years old should not be given aspirin).
- Use a spray or cream that contains local anaesthetic, antihistamine or mild hydrocortisone (1%) on the affected area to prevent itching and swelling.
- Take an antihistamine tablet to help reduce swelling (antihistamine tablets are available on prescription or from pharmacies).
If you have an allergic reaction after a sting, even if it is just a skin rash (hives), you may be prescribed an adrenaline pen (called an auto-injector) by your GP and shown how to use it. You will also be referred to an allergy clinic to see an immunologist for further tests and treatment.
Emergency treatment
If you have swelling or itching anywhere else on your body after being stung, or if you are wheezing or have difficulty swallowing, you will need emergency medical treatment. Call 999 immediately and ask for an ambulance.
Read more about the symptoms of an insect sting.
If you have the symptoms of a systemic reaction (SR), it could lead to anaphylactic shock. If you experience anaphylaxis, you may need to have an adrenaline injection, antihistamines, oxygen or an intravenous drip (a drip directly into a vein).
Immunotherapy treatment
Your GP or immunologist (an immune system specialist) may also suggest venom immunotherapy (VIT). This is sometimes known as hyposensitisation. It involves being injected with small doses of venom every week and being observed to check for an allergic reaction.
Your body soon becomes used to the venom (desensitised) and will start to make antibodies to prevent further reactions.
When a high enough dose has been reached, the injections will be given monthly and could last for a further two or three years.
Your immunologist will decide how much venom is injected and how long the injections need to continue for. This will depend on your initial allergic reaction and your response to the treatment.
Infection
If the sting becomes infected, you may need treatment with antibiotics.
See your GP if the sting fills with pus and feels tender to touch, your glands swell up and you feel unwell with flu-like symptoms.
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Prevention
There are several things you can do, in the home and outside, to help prevent an insect sting or the severe consequences of an allergic reaction.
The advice below will help you avoid getting stung by an insect:
- Move away slowly without panicking if you encounter wasps, hornets or bees. Do not wave your arms around or swat at them.
- Use an insect repellent if you are planning to spend time outdoors, particularly in the summer or early autumn when stings are most likely to occur.
- Never disturb an insect nest and avoid clusters of flowers and piles of wood where insects gather. If you find a nest in your garden or near your house, call an exterminator from your local council to have it removed safely. Wasps build nests in sheltered areas including trees and roof spaces.
- Keep food and drink covered when eating or drinking outside, particularly sweet things. Wasps or bees can also get into open drink bottles or cans that you are drinking from.
- Fallen fruit and open dustbins can also attract wasps. It may help to regularly and carefully remove any fallen fruit in your garden, and keep a well-fitting lid on any dustbins.
- Wearing a long-sleeved top and trousers is the best way to avoid getting stung while you are outside. Wearing socks and shoes will help protect your lower legs and feet. Insects are often attracted to brightly coloured clothing and strong perfume or body lotion.
- Keep the windows of your car closed to stop insects getting inside.
- Keep doors and windows closed or put thin netting or door beads over them to prevent insects getting inside the house.
Systemic reaction (SR)
Someone who has a history of allergies to insect venom will be referred to an allergy specialist. They may be given a syringe (called an auto-injector), which is pre-loaded with adrenaline, as well as instructions about how to use it. The auto-injector can be prescribed by an allergy specialist.
You will be taught how to use it, and your close relatives and friends can also be given training. Make sure the adrenaline is not out of date.
Some people with known severe allergies choose to carry a card or wear some form of tag, such as a medical alert bracelet or necklace. It will make others aware of your allergy and the required treatment. Speak to your GP if you are thinking about doing this.
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