Many insects sting as a defence mechanism by injecting venom into the skin. In the UK, stinging insects include:

• bees (honeybees and bumblebees)
• wasps
• hornets

Insect stings usually cause a swollen, red, raised mark to form on the skin. This is known as a weal. The affected area will often be painful and itchy. This will usually last for a few days. See the symptoms section for more information.

Sting or bite?

As well as insects that sting, some insects bite. In the UK, insects that bite include:

• mosquitoes
• fleas
• ticks

See the encyclopaedia topic about insect bites for more information, including how to treat them.

Outlook

After stinging someone, bees leave behind their sting and a venomous sac in the wound. This should be removed immediately by scraping it out with something that has a hard edge, such as a bank card. Wasps and hornet can continue to sting so you should move away from the area.

Insect stings can be painful but most are harmless and only affect the area around the sting.

However, some people can have an immediate and more widespread allergic reaction to being stung. This is known as anaphylactic shock, which can sometimes be fatal. See the encyclopaedia topic for more information about anaphylaxis.

Anaphylactic shock after an insect sting is quite rare, affecting approximately three people in 100. It usually only occurs after a wasp sting.

If you are stung by an insect, such as a wasp, the area around the sting will become inflamed (swollen), go red and a raised mark (weal) will form. The affected area will often be quite painful and itchy. This will usually last for a few days.

People who have an allergic reaction to an insect sting will experience more symptoms. 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

The allergic reaction can either be:

• a localised allergic reaction: which will be more painful than a normal insect sting
• a systemic allergic reaction: which will require immediate medical assistance

Localised allergic reactions and systemic allergic reactions are described in more detail below.

Localised allergic reaction

If you have a localised allergic reaction 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 experience a localised reaction several hours after being stung. This could include:

• a rash,
• nausea
• painful or swollen joints

Systemic allergic reaction

A systemic allergic reaction can cause anaphylactic shock and will present the same symptoms as anaphylaxis.  

Seek emergency medical treatment if, immediately after being stung, you experience any of the following:

• swelling or itching anywhere else on your body
• a skin reaction anywhere else, particularly pale or flushed (red or blotchy) skin
• wheezing, hoarseness or any 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

Call 999 to request an ambulance immediately as this kind of reaction can be fatal.

Bee stings have a venomous sac attached. After you have been stung, the sting and the venomous sac will remain behind and the bee will die.

Wasps and hornets do not usually leave the sting behind and therefore could continue to sting you. If you have been stung and the wasp or hornet remains in the area, walk away calmly to avoid getting stung again. 

Remove the sting immediately

As soon as you have been stung by an insect, you should remove the sting and the venomous sac. Do this by scraping it out, either with your fingernails, or 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 that you do not puncture the venomous sac. Do not attempt to pinch the sting out with your fingers or a pair of tweezers, as you may spread the venom. If a child has been stung, an adult should remove the sting.

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 (see below)
• keep children’s fingernails short and clean

Visit your GP if the redness and itching get worse or do not clear up after a few days.

Advanced treatment

If the sting is painful, you can take the following further measures:

• place a bag of frozen peas on the swelling or some ice wrapped in a towel
• take painkillers, such as paracetamol or ibuprofen (children who are under 16 years of age should not be given aspirin)
• use a spray or cream containing local anaesthetic, antihistamine or mild hydrocortisone (1%) on the affected area to prevent itching and inflammation (swelling)

Emergency treatment

If you experience swelling or itching anywhere else on your body after being stung or, if you are wheezing or having difficulty swallowing, you will require emergency medical treatment. Call 999 immediately to request an ambulance.

See the symptoms section for the full list of symptoms associated with a systemic allergic reaction.

If you have the symptoms of a systemic allergic reaction, 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).

Further treatment

Following treatment for an insect sting, you may be referred to an allergy clinic, or immunologist (a specialist on the immune system). If you have had a severe or potentially life threatening allergic reaction, it is very likely that you will be referred.

Your GP may also suggest venom immunotherapy treatment, which is sometimes known as hyposensitisation. This involves having injections on a weekly basis with small doses of venom, and being observed for about an hour or so to check for an allergic reaction.

The regular injections will desensitise you to the venom (make you used to it), as well as encouraging your body to make antibodies to stop further reactions. The injections will carry on with increasing amounts of venom and will change to monthly appointments when a high enough dose has been reached. The injections could last a further two or three years.

The actual amount of venom injected and the length of time that the injections continue for will be decided by your immunologist. This will depend on your initial allergic reaction and your response to the treatment.

Infection

If the sting becomes infected, it will be more painful, turn redder, and pus may build up inside the affected area. Your glands may swell up as they fight the infection, and you may feel unwell with flu-like symptoms. The affected area will feel tender and you may need treatment with antibiotics. You should visit your GP if you suspect that the insect sting has become infected

There are several measures that you can take, both in the home and outside, to help prevent an insect sting or the severe consequences of an allergic reaction.

The advice outlined below will help you to 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.
• Never disturb an insect’s 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 to have it removed safely.
• Keep food and drink covered when eating or drinking outside, particularly sweet things. Beware of wasps or bees getting into open drink bottles or cans that you are drinking from.
• 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.

Allergic reactions

If you are allergic to wasp or bee stings, carry a syringe (auto-injector) that is pre-loaded with adrenaline (as well as instructions about how to use it) with you at all times. The auto-injector will be prescribed by your GP or allergy specialist.

You will be taught how to use it and, if necessary, your relatives and/or close friends can also be given training. Make sure that the adrenaline is not out of date.

Some people who are known to have severe allergies decide to carry a card or wear some form of tag, such as a medical alert bracelet or necklace. This will help to make others aware of your allergy and the required treatment. Speak to your GP if this is something that you are considering.