Allergies to bites and stings

Bites and stings usually cause irritation of the skin. This irritation is not an allergic response, but some people do develop allergic symptoms that can range from mild to severe and life threatening. Stinging insects such as bees, wasps and ants are among the most common causes of these reactions. Biting insects such as mosquitoes, midges and ticks are less likely to trigger a severe reaction, although their bites can still cause milder allergic symptoms.

How insects cause allergic reactions#

The venoms of stinging insects such as bees, wasps and ants are one of the most common causes of severe allergic reactions (anaphylaxis). Being allergic to one type of stinging insect does not mean you will be allergic to another. Biting insects such as midges and mosquitoes are more likely to cause local reactions, such as redness and swelling, but can occasionally cause broader allergic reactions.

When you are allergic to an insect, your immune system reacts to specific triggers known as allergens. It produces antibodies that detect the allergen and set off inflammatory reactions, including the release of chemicals such as histamine. The resulting reactions range from mild local symptoms at the site of the sting or bite to severe, life-threatening anaphylaxis.

Bees#

Bees can sting only once, because they inject a venom sac into the skin and then die. Honey bees are a very common cause of insect-sting allergy, and native bees can also cause allergic reactions.

Wasps#

Unlike bees, wasps do not leave a sting behind and can sting several times.

Stinging ants#

Some ants can deliver very painful stings that cause generalized or severe allergic reactions, and certain species are an important cause of anaphylaxis in some regions.

Ticks#

The saliva of some ticks causes an allergic reaction in certain people. Ticks live on vegetation and attach to and bite into the skin of people and animals. If you disturb or try to remove a tick, it can inject more saliva, which can cause a life-threatening reaction in people who are allergic. People with tick allergy can sometimes also become allergic to red meat (mammalian meat) and to gelatine.

Symptoms#

Adults are generally at greatest risk of a severe allergic reaction. Stings and bites often hurt and can cause minor redness and itching at the site, but these symptoms on their own are not caused by an allergic reaction.

Local skin reactions#

Some people have a reaction that causes a rash or a large area of swelling around the site of the sting or bite. These local reactions are not life threatening.

Generalized reactions#

A generalized allergic reaction affects parts of the body beyond the site of the sting or bite. Symptoms can include red, swollen skin, a rash or hives (urticaria). Although these symptoms are not life threatening, you should see your doctor if you have had a generalized reaction, as you may be referred to a clinical immunology/allergy specialist.

Severe allergic reaction (anaphylaxis)#

Severe allergic reactions after an insect bite or sting are potentially life threatening. Symptoms can include:

• difficult or noisy breathing
• swelling of the tongue
• swelling or tightness of the throat
• difficulty talking or a hoarse voice
• wheezing or coughing
• persistent dizziness or collapse
• floppiness in young children

Milder symptoms such as swelling of the lips, face and eyes, hives or welts, a tingling mouth, abdominal pain or vomiting can come before a severe reaction and are warning signs of anaphylaxis.

If you have had any of these symptoms after an insect sting or bite, you are at greater risk of another severe reaction if you are stung or bitten by the same type of insect. Ask your doctor to refer you to a clinical immunology/allergy specialist.

Diagnosis#

If you think you may have an allergy after being bitten or stung, keep a diary of your symptoms to help you and your doctor understand the cause. Note whether your symptoms occur inside, outside or both, how long they last, the time of day or year, and whether you were near animals.

To diagnose your allergy, your doctor may refer you to a clinical immunology/allergy specialist, who can test for allergies using several methods depending on the suspected cause. Testing for a bite or sting allergy may use skin testing or allergy blood testing. Testing for related allergies, such as to red meat and gelatine, is more complicated, so talk to your doctor or specialist.

Avoid unproven allergy tests#

A number of methods claim to test for allergies but have not been scientifically proven. They are often costly and can lead to dangerous avoidance of certain foods. Unproven methods include cytotoxic food testing, electrodermal testing, hair analysis, iridology, kinesiology, pulse testing, reflexology and Vega testing. Always speak with your doctor before using a complementary medicine or therapy.

Reducing the risk of bites and stings#

The best strategy is to reduce your risk of being bitten or stung:

• Cover up with long-sleeved shirts and long trousers.
• Tuck your shirt into your trousers and your trousers into your socks.
• Wear light-coloured clothing.
• Wear shoes when outdoors.
• Use an insect repellent containing DEET.
• Avoid being outdoors near dawn or dusk.
• Check whether ticks are common in your area.
• Avoid bees and wasps, and have professionals remove wasp, bee and ant nests near your home.

People who are older or have breathing problems are at greatest risk of a severe reaction and should be seen by a clinical immunology/allergy specialist. If you have had a severe allergic reaction to a stinging insect, you are more likely to have one again if stung.

If you are at risk of anaphylaxis#

• Carry an adrenaline injector (such as EpiPen® or Anapen®) to treat a severe allergic reaction, along with a means of calling for help such as a mobile phone.
• Consider wearing medical identification jewellery, which increases the likelihood that adrenaline will be given in an emergency.
• Where possible, avoid medication that may increase the severity of a reaction or complicate its treatment, such as beta blockers.

Always dial your local emergency number (for example 911 in the US and Canada, 112 across the EU and many countries, 999 in the UK, or 000 in Australia) to call an ambulance in a medical emergency. Do not allow the person to stand or walk.

First aid#

Bee stings#

Bees often leave a barbed sting in the skin. Flicking the sting out of the wound within about 30 seconds helps reduce the amount of venom entering your body. Use the edge of a fingernail, a credit card or a key to flick the sting out. Do not pull or squeeze the venom sac, as this may inject more venom. Wasps do not leave a sting behind but can sting several times.

Minor allergic reactions#

• Apply a cold pack to the area.
• Apply soothing creams.
• Take oral antihistamines to help reduce itching.

For large, painful areas of swelling, you may need to see your doctor for cortisone tablets to reduce the swelling.

Tick bites#

For all tick bites, first kill the tick with a rapid-freezing spray so it cannot inject saliva into your body. Once the tick is dead, remove it as soon and as safely as possible. This reduces the risk of infection or tick paralysis. If you are not allergic to ticks, correct and rapid removal can reduce the risk of developing an allergy.

Avoid the common advice of using tweezers to pull a live tick out of the skin. If you are allergic to ticks, you are at risk of anaphylaxis if bitten, so:

• Kill the tick by freezing it with a rapid-freezing spray to stop it injecting saliva.
• Have the tick removed in a hospital emergency department, especially if you are highly allergic.

Some people who are less highly allergic can be trained by a healthcare professional to safely remove ticks. Ether-containing sprays that freeze and kill ticks are available at pharmacies. Freezing and killing ticks before removal is also recommended for people who are not allergic.

Venom immunotherapy#

In some cases, a clinical immunology/allergy specialist may suggest venom immunotherapy (VIT), also known as desensitization. It involves a series of injections of commercial venom preparations, usually over 3 to 5 years. This can help improve tolerance of the insect venom and reduce symptoms. Venom immunotherapy is not available for tick allergies.

Key points#

• Stings from bees, wasps and ants are a common cause of severe allergic reactions (anaphylaxis).
• Being allergic to one type of stinging insect does not mean you are allergic to another.
• Bees can sting only once and then die; wasps do not leave a sting and can sting several times.
• People with tick allergy can sometimes become allergic to red meat and gelatine.
• If you are at risk of anaphylaxis, carry an adrenaline injector and seek urgent medical help if stung or bitten.

Where to get help#