Overview

Many insects, such as the following, cause mild reactions:

• Bedbugs.
• Kissing bugs.
• Chiggers.
• Fleas.
• Flies.
• Mites.
• Mosquitoes.
• Non-poisonous spiders.
• Ticks.
• Scabies.
• Lice. For more information on lice, see the topic Body Lice, Head Lice, or Pubic Lice.

Some insects are more likely than others to cause allergic or toxic reactions.

Bites and stings are more serious if you develop one or more of the following conditions after an insect or spider bite or sting:

• A severe allergic reaction (anaphylaxis)
• A toxic reaction
• A large skin reaction with swelling and redness that spreads away from the site of the bite or sting. It may be as large as swelling across two major joints, such as from the elbow to the shoulder.
• Signs of a skin infection
• Serum sickness