Insect bites and stings

By Dr Ananya Mandal, MD

Insect bites and stings may cause minor pain and irritation but some may be extremely painful and may also trigger a serious allergic reaction.

In the United Kingdom common insect bites include mosquitoes, fleas, ants, midges, bedbugs, spiders, mites and ticks. The last three are not insects but arachnids.

Insects that may sting include bees, wasps and hornets. While an insect bites to puncture the skin often to feed on human blood, an insect stings as a defence and may inject venom into the skin. 1-5

What are the symptoms of insect bites & stings?

If an insect bites, it wets the area with its saliva. This may lead to an allergic reaction in the skin making the area around the bite to turn red, itchy and sometimes swollen.

After a sting too the venom causes a local allergic reaction to make the skin swollen, itchy and red and is termed a weal. The pain and itchiness may remain for a few days and is usually mild and harmless.

The severity of the reaction, however, depends on the sensitivity of the bitten person. If the person is allergic to the venom or to the bite there may be a mild to severe general allergic reactions. One such reaction is hypersensitivity reaction or anaphylaxis. This requires immediate medical treatment and even hospitalization to prevent death.

When to see a doctor?

A doctor needs to be consulted if the swelling and blistering covers large areas of the body or if there are other features like fever, pus formation (indicating infection) or allergic reactions with difficulty breathing, swelling of face and neck etc.

The following signs should see a doctor as soon as possible:

  • nausea

  • vomiting

  • diarrhoea

  • rapid heart rate

  • shallow breathing

  • difficulty swallowing

  • rapid fall of blood pressure

  • shock

  • confusion

  • agitation

What is the treatment of insect bites and sting?

The most common treatments may be done at home and are usually enough to cure the symptoms.

The affected area needs to be washed with soap and water to remove the allergenic venom or sting. The sting, if visible may be removed before washing or any treatment is attempted. A cold compress may be placed over the area to reduce the swelling and ease the pain. Pain relievers like Paracetamol or Ibuprofen may be taken.

Those with a more serious allergy usually need therapy at the hospital. Those with anaphylaxis or severe allergies may need to be given adrenaline injection as an emergency life saving measure and may need hospital admission.

How can insect bites and stings be prevented?

Insect bites and stings are common if time is spent out of doors especially in the wild. Common measures to prevent bites include wearing covered clothes, wearing or using an insect repellent, staying indoors after dusk and using insect screens etc. Avoidance and backing away gently from stinging insects like bees, wasps and hornets helps prevent stings.

Those travelling abroad like Africa, Asia and South America are at risk of insect bites like mosquito bites that may transmit malaria and other diseases like:

  • Yellow fever from mosquitoes in Venezuela

  • relapsing fever and Chagas disease from bed bugs in Mexico

  • Lyme disease and Rocky Mountain spotted fever from ticks in eastern US states

Other insect bourne diseases include dengue, onchocerciasis, trypanosomiasis, leishmaniasis and loiasis.

Necessary precautions, medication or vaccination before travel is essential. Studies have shown no evidence of HIV transmission through mosquito or other insect bites however.

Reviewed by , BA Hons (Cantab)

Further Reading

Last Updated: Sep 11, 2012

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