Bed Bugs: Bites, Signs of an Infestation and Where They Hide

A bed bug on a human host. Image from CDC's page on bed bugs.

In brief

• Bed bugs are not known to spread diseases to people.
• Their bites can cause itching and lost sleep, and in rare cases an allergic reaction.
• The way to prevent them is to check regularly for signs of an infestation.

What bed bugs are

Bed bugs (Cimex species) are small, flat insects that bite people and animals at night, while they sleep, and feed on their blood. They are reddish-brown and wingless, and measure 1 mm to 7 mm — roughly the size of Lincoln's head on a penny. They can go several months without feeding.

They do not carry disease, but they cause irritation, itching and loss of sleep, and getting them out of a home can be expensive and inconvenient.

Where they are found

Everywhere: North and South America, Africa, Asia and Europe. They turn up in five-star hotels and resorts too. How clean a place is does not decide whether it has bed bugs.

Infestations are usually where people sleep — apartments, shelters, houses, hotels, cruise ships, buses, trains and dorm rooms. By day the bugs hide on or near the bed:

• in the seams of mattresses
• in box springs
• in bed frames and headboards
• in dresser tables
• in cracks and crevices
• behind wallpaper

They can travel more than 100 feet in a night, but tend to live within 8 feet of where people sleep.

How they spread

Bed bugs are experts at hiding: their slim, flat bodies fit into very small spaces. They ride along in the seams and folds of luggage, overnight bags, folded clothes, bedding and furniture. Most people carrying them do not know it, and spread them as they travel.

Anyone visiting an infested place can pick them up. The risk is higher for people who travel often and share living and sleeping spaces where others have slept before.

Bites

Bites affect people differently. Some people show no marks at all; some get small bite marks; a few have serious allergic reactions.

When a bed bug bites, it injects fluids — an anesthetic and an anticoagulant — so the person does not feel it. Most people only notice the marks one to several days later, and in some people they take as long as 14 days to appear.

The marks look like mosquito or flea bites: a slightly swollen red patch that may itch. They may be scattered or in a straight line. Bites can also bring insomnia, anxiety, and skin problems from intense scratching — which can lead to a secondary skin infection.

An allergic reaction can show as enlarged bite marks or painful swelling at the bite, and on rare occasions as anaphylaxis. If you think you are reacting to bed bug bites, speak to your health care provider.

Signs of an infestation

Bite marks on the face, neck, arms, hands or elsewhere after sleeping are one of the easiest signs — but since they can take up to two weeks to appear, look for other clues as well:

• shed skins (exoskeletons, left after molting)
• bed bugs in the folds of mattresses and sheets
• rusty-colored blood spots on mattresses or nearby furniture
• a sweet, musty odor

Finding and getting rid of them early makes an infestation easier to control. Travelers can check sleeping areas for shed skins or bugs in the folds of mattresses and sheets. CDC's DPDx page shows the bed bug's life cycle.

Treatment

Bites usually need no medical treatment. Antiseptic creams or lotions help with the itching; avoid scratching, which can infect the skin. For itchy, inflamed reactions, an antihistamine may help.

An infestation is a job for a professional pest control company that has experience with bed bugs. They will usually treat the area with insecticide sprays.

Sources

Based on "About Bed Bugs," Centers for Disease Control and Prevention; a work of the United States government in the public domain. A misspelling in the source ("loss off sleep") is corrected.