Fleas are small, wingless parasitic insects that have a hard, shiny surface and travel by jumping. Flea bites usually cause only mild symptoms in humans that can be relieved by home treatment measures, such as nonprescription cortisone cream.

Signs and symptoms of flea bites may include:

• Zigzag lines, especially on the feet and legs and in the waist areas.
• Intense itching.
• A single hive or wheal.
• Dull red spots that last even after other symptoms disappear.
• Blisters or open sores in highly sensitive people.

Adult fleas may live in floor crevices, debris, and carpeting for years and can survive for months without feeding. In rare cases, they can carry disease, such as plague. Destroying household fleas (extermination) is an important part of treatment.