How do I know if I have bed bugs, and what do I do?

Confirming it is actually bed bugs rather than something else, the containment steps that matter before anyone treats, and why this one is not a DIY job.

Difficulty: advanced
Time: 4 hr
Read: 5 min
Safety: restricted

Short answer

Look for live insects and dark spotting along mattress seams, the bed frame joints and the headboard — bites alone prove nothing. If you find them, do not start moving furniture around: contain the room, bag and hot-wash textiles inside the room, and call a professional. Widespread insecticide resistance means amateur treatment usually makes it worse.

Bed bugs are the household pest where the standard advice is unambiguous: get a professional. They hide in cracks a millimetre wide, they survive months without feeding, resistance to common insecticides is widespread, and the single most effective way to spread them through a building is to start carrying infested items about. Everything below is written around those facts.

Safety

Bed bugs are a professional job in almost every case, and attempting to treat them yourself usually spreads them through the property. Never move a mattress, bedding or furniture out through the house — that is the main way an infestation reaches other rooms and neighbours. Do not use unlicensed insecticides, foggers or petrol-based products; there have been house fires and poisonings from improvised treatments. If you live in a flat, tell the managing agent, because adjoining properties are almost certainly involved.

What you'll need

A bright torch and a magnifier or a phone camera
Sealable bags or plastic boxes
Mattress and box-spring encasements, after treatment (optional)
A steam cleaner, used carefully (optional)

Step by step

Do not rely on bites to diagnose it.Bites vary enormously — some people react strongly, some not at all, and the classic line of three is far from universal. Carpet beetle hairs, fleas, scabies and skin conditions are all commonly mistaken for bed bugs. You need to find the insect or its traces.
Search the bed itself first, thoroughly.Strip it. Look along mattress piping and seams, in the label folds, into every joint of the frame, inside screw holes and under the headboard — including where it meets the wall. Use a bright torch at a low angle.
Learn what you are looking for.Adults are 4-5mm, flat, oval and reddish-brown, like a small apple pip. Also look for dark ink-like spotting on the fabric, pale shed skins, and tiny pale eggs in crevices. A sweet musty smell in a heavy infestation is real but not reliable.
Widen the search only after the bed.Bedside furniture, the skirting behind the bed, curtain hems, sockets, picture frames and the seams of a chair used at night. They stay close to where people sleep — usually within two metres.
Stop moving things.The instinct is to strip the room and carry everything to the washing machine or the tip. That is how an infestation in one bedroom becomes an infestation in the whole house and, in a flat, in the block. Contain first.
Bag textiles inside the room.Seal bedding and clothes in bags where they are, carry the sealed bags to the machine, and wash at 60 degrees followed by a hot tumble dry. Heat kills all stages; the sealed bag is what stops the journey spreading them.
Keep sleeping in the room.This sounds wrong and it matters. Moving to the sofa or a spare room takes the bugs with you and spreads the infestation. Stay put until it is treated.
Call a professional early.A BPCA or NPTA member, or your council's pest service. Treatment is normally two or three visits, and may combine heat treatment with residual insecticide. Ask specifically about their approach to resistance and whether follow-up visits are included.
Tell the landlord or managing agent if you rent.In writing, immediately. In a flat, adjoining properties are very likely involved and a treatment of one flat alone frequently fails. This is a building-wide problem more often than a household one.
Prepare the room the way the controller asks.They will give a preparation list — usually declutter, wash and bag textiles, pull furniture from the walls. Follow it exactly, because poor preparation is one of the main reasons treatment fails.
Encase the mattress after treatment.A proper bed bug-proof encasement on the mattress and base traps anything remaining and makes future monitoring straightforward. Leave it on for at least a year.
Monitor for months, not weeks.Interceptor cups under the bed legs are cheap and give a clear read. Do not declare it over until several weeks have passed with nothing caught after the final treatment.

Tips

Never take a discarded mattress or upholstered furniture from the street. It is one of the most common ways an infestation starts.
When you come home from a hotel or a hospital stay, unpack in the bathroom or the hall, and put everything washable straight through a hot wash and dryer.
Keep the treatment paperwork. If you rent, it matters; and if it recurs it tells the next controller what was used.

Common mistakes

Throwing the mattress out immediately — It spreads bugs through the house on the way out, costs money that is better spent on treatment, and a new mattress in an untreated room is infested within weeks.
Buying a supermarket spray and treating it yourself — Resistance to common amateur actives is widespread, partial treatment scatters the population deeper into the structure, and it makes subsequent professional treatment harder and longer.

If it doesn't work

Bites but nothing found after a thorough search

Cause: Often not bed bugs at all — Fix: Check for carpet beetle larval skins along carpet edges, and consider fleas or a skin condition. Interceptor cups under the bed legs for a fortnight will confirm or rule out bed bugs.

Treated once and they came back

Cause: Single treatment, poor preparation, or an untreated adjoining property — Fix: Insist on the full course of visits, prepare exactly as instructed, and in a flat push for adjoining properties to be inspected.

Found them in a sofa rather than a bed

Cause: Someone sleeps there, or the infestation has spread — Fix: Tell the controller — the treatment plan changes. Do not move the sofa out of the room in the meantime.

Questions people ask

Do bed bugs mean the house is dirty?

No. They are entirely unrelated to cleanliness — they are carried in on luggage, second-hand furniture and clothing, and they occur in immaculate homes and hotels alike. Clutter makes treatment harder, but it does not cause them.

Can I use a steam cleaner myself?

Steam kills on contact and can help along seams and edges, but it only reaches what you touch and it puts moisture into furniture. It is a supplement to professional treatment, not a substitute, and it will not reach bugs in the frame or the wall.

Who pays if I rent?

It depends on the tenancy and how it arose, and it is often disputed. Report it in writing immediately, keep the correspondence, and involve the letting agent early. In a block, the managing agent usually has to coordinate treatment across flats for it to work at all.