Insects, stings and bites
Stinging insects which are common in the UK include: wasps, honey bees, and hornets. The sting is due to venom (like a poison) which the insect injects' into the skin.
Biting insects which are common in the UK include: midges, gnats, mosquitoes, flies, fleas, mites, ticks, Horse Fly's and bedbugs.
The rest of this document just deals with insect stings not insect bites..
What may happen after an insect sting?
In most cases
An insect sting typically causes an intense, burning pain. This is quickly followed by a patch of redness and a small area of swelling (up to 1 cm) around the sting. This usually eases and goes within a few hours.
In a few cases
Some people also have an allergic reaction to the venom in the sting. The reaction can cause localised and/or generalised symptoms
A localised allergic reaction causes swelling (oedema) at the site of the sting. This becomes larger over several hours, and then gradually goes away over a few days. The size of the swelling can vary, but can become many centimeters across. The swelling may even extend up an entire arm or leg. The swelling of a local reaction is not dangerous unless it affects your airway. However, if it is severe the skin may break out in blisters.
A generalised (systemic) allergic reaction can cause one or more of the following:
- itchy skin in many parts of the body, followed by an itchy blotchy rash which can appear anywhere on the body.
- swelling of your face which may extend to include swelling of the lips, tongue, throat, and upper airway
- abdominal cramps and feeling sick.
- general redness of your skin.
- a fast heart rate.
- low blood pressure which can make you feel faint, or even to collapse.
- wheezing or difficulty in breathing due to an asthma attack or throat swelling.
A generalised reaction usually develops within 10 minutes of a sting. It can be fairly mild, for example, a generalised itchy rash and some mild facial swelling. In some cases it is severe and life-threatening, for example, severe difficulty breathing and collapse. A severe generalised allergic reaction is called anaphylaxis and is a medical emergency. If you have many bee or wasp stings at the same time, this can also cause serious illness. This is usually due to the high dose of venom directly, rather than to an allergy.
What is the treatment for an insect sting?
Scrape out the sting left in the skin as quickly as possible. Under no circumstances try to pluck or pull it out. Use the edge of a knife, the edge of a credit card, or a finger nail. The quicker you remove the sting the better, so use anything to scrape out the sting.
If any symptoms of an allergic reaction develop shortly after being stung (see above) then:
Call an ambulance immediately.
If there is no allergic reaction (most cases) then:
A cold compress will ease the pain and help to minimise any swelling. For example, use a cold flannel or an ice pack.
A painkiller may help to ease the pain
If there is a localised allergic reaction (swelling around the site of the sting) then:
Take an antihistamine tablet as soon as possible. You can buy these at pharmacies, or get them on prescription. (Antihistamines block the action of histamine which is a chemical that is released by certain cells in the body during allergic reactions.)
Use a cold compress to ease pain and to help reduce swelling. For example, use a cold flannel or an ice pack.
Consider taking painkillers to ease the pain. Continue with regular antihistamine tablets until the swelling eases. This may be for a few days.
What are my chances of having an allergic reaction to a sting?
Most people do not have an allergic reaction to insect stings.
About 3 in 100 people who are stung have some kind of allergic reaction. Only in some of these is the reaction severe.
Some points about allergies to insect stings
In the UK most allergic reactions are caused by wasp stings.
You do not get an allergic reaction after a first sting by a particular type of insect. You need one or more stings to 'sensitise' your immune system.
Sometimes it takes many stings to sensitise you. This is why some bee keepers who have had many previous stings may suddenly develop an allergic reaction to a bee sting.
Bee and wasp venoms are different. People who are sensitised and 'allergic' to wasp venom are rarely allergic to bee venom.
Up to half of people who have had a previous generalised reaction to a sting have no such reaction, or only a milder reaction, to a further sting.
But, the course can be variable. A series of stings may result in a generalised reaction, no reaction, and then another generalised reaction. The reason why some people have variable reactions to a series of stings is not clear. So, if you have a generalised reaction to a sting, it does not necessarily mean it will happen again if you are stung again. However, you cannot predict what will happen next time you are stung, so your doctor may refer you to an allergy clinic.
Advice and treatment following a reaction to as sting
An allergy clinic will be able to do tests to confirm which type of sting you are allergic to. There are then two possible options which may then be considered:
1. To give you a supply of emergency medication to use when necessary Some people are given a pre-loaded syringe of adrenaline together with a written treatment plan to cope with any future stings. You (and relatives) can be taught how and when to use the treatments provided.
2. Desensitisation This is where you are given injections of tiny amounts of venom from the type of insect that causes your allergic reaction. Repeated doses of venom over several weeks can 'desensitise' your immune system, and so you will not react severely next time you are stung.