Insect Bites and Stings

Introduction

Insects

  • Stinging insects - those that use some sort of venom as a defence mechanism or to immobilize their prey. Examples include bees, wasps and ants.
  • Biting insects - those that feed off the blood supply of humans and other creatures. Examples include mosquitoes, ticks and fleas.



Clinical Features

Reactions to insect bites or stings are generally mild, but local or systemic reactions can occur due to hypersensitivity, allergic reaction, transmission of infection, or envenomation.

Itching papules, which can be intense, is the hallmark symptom of insect bites.

  • Weals, bullae and pain can occur, especially in sensitized individuals.
  • Lesions are often localized and grouped together, and occur on exposed areas, for example hands, ankles and face.
  • Scratching can cause excoriation, which might lead to secondary infection.

In contrast, stings are associated with intense burning pain.

  • Erythema and oedema follow but usually subside within a few hours.
  • If systemic symptoms are experienced, they occur within minutes of the sting.



Referral

Patients with systemic symptoms (e.g. anaphylaxis results in immediate angioedema, urticaria, and bronchospasm and can be life-threatening) should be referred to the emergency department immediately.



OTC Treatment

Insect bites and stings are common, and many patients will self-manage mild reactions at home.

Small local reactions

  • If needed, remove stinger immediately (within 20 seconds) may decrease venom injection.
  • Wash the area with soap and water.
  • Local pain and swelling is best treated with cold compresses/ice and, if needed, oral pain killers (ibuprofen or paracetamol).
  • Local itching can be treated with calamine lotion or topical crotamiton or low potency corticosteroids (hydrocortisone 1%).
  • If itching interferes with sleep, then oral sedating antihistamine might be helpful at night.

Large local reactions

  • Occasionally, severe pain and swelling can extend beyond the immediate surroundings of the lesion.
  • They should be managed with oral pain killers and antihistamines.

NOTE: Following an insect bite or sting, itching and redness of the skin are common and may last for up to 10 days. As long as your symptoms are improving and you feel well in yourself, you don't need to seek help.



Prevention

  • Wear fully covering clothing.
  • Keep windows and doors closed at night.
  • Apply insect repellents to exposed skin.



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