A mattress is the first place to look when you suspect bed bugs. It is also where most evidence collects, because the insects stay close to where people sleep. This guide shows you how to check it methodically, without panic and without special kit.
Before you start
Gather a torch, a magnifying glass or phone camera, a ruler and a pair of gloves. You will also want a clear plastic bag or a sealable tub, in case you find a live insect. Strip the bed and put the bedding straight into a bag so nothing is shaken around the room.
Work in good light and take your time, because small details matter. The NHS describes bed bugs as roughly 5mm long and dark yellow, red or brown. That is small enough to miss at a glance.
Keep a note of what you find and where. A simple list on your phone is enough, since it will help if you later use the five-question checker or ask someone to confirm what you have seen.
What you are looking for
There are four kinds of evidence worth knowing. Each one looks different, and none of them is proof on its own. However, several together build a much clearer picture.
The first is the insect itself. Adults are flat, oval and wingless, and nymphs are smaller and paler. If you are unsure about shape, our bed bug signs guide shows what to compare.
The second is dark spots. The NHS lists small brown spots on bedding or furniture, which are bed bug droppings. The US EPA says these can look like marks made by a marker pen on fabric.
The third is blood spots. The EPA notes rusty or reddish stains on sheets or mattresses, caused by bugs being crushed. The fourth is eggs and shed skins. Eggs are tiny and pale, around 1mm, and our guide to what bed bug eggs look like explains how to tell them from lint and fabric fibres.
Step 1: Check the seams and piping
Start with the mattress seams, because the CDC lists mattress folds and seams among the main places to look. Run your torch slowly along the piping on the top edge. Then turn to the sides and repeat.
Pay special attention to the corners. Bed bugs are flat, and the EPA says they are only about the width of a credit card, so they slip into very narrow gaps. Fabric pinched at a corner or under a label is a favourite spot.
Look for the tag stitched to the side of the mattress. Lift it gently and check underneath. For example, dark specks that smear or stain when touched with a damp tissue are more likely to be droppings than dirt.
Step 2: Check the underside and the base
Next, lift the mattress. Work along the underside, paying attention to any dust cover or fabric stapled to the base. Gaps where the cover has loosened can hide evidence.
Then move to the bed base. Divan bases have a fabric underside that is worth peeling back where it is fixed at the edges. Slatted frames have joints and screw holes that can hold droppings.
Take your time with wooden frames, since they have many joints. Look at each slat end, each bracket and each crack. Evidence here tends to be small clusters rather than scattered marks.
Step 3: Check the headboard and nearby furniture
The headboard is often overlooked. If it is fixed to the wall, check the gap behind it using a torch and a phone camera held at an angle. Wall-mounted headboards and panelling give the insects plenty of narrow spaces.
Then widen your search. According to the CDC, bed bugs tend to live within about 8 feet of where people sleep. Bedside tables, drawer runners and the underside of lamps are worth a quick look.
Do the same for any upholstered chair beside the bed, as bugs do not stay only on the mattress. Check seams, zips and the folds beneath cushions. Our guide to where bed bugs hide in a bedroom walks through the whole room if you want a longer checklist.
How often to repeat the check
One inspection is a snapshot. If you found nothing but still have bites or worries, repeat the check after a few days. Evidence builds slowly, so a second look can reveal marks that were not there before.
Meanwhile, keep the bed tidy and avoid piling clothes against it. Clutter gives hiding places and makes later checks harder. Wash and dry bedding as the NHS suggests, using a hot wash of 60C where the fabric allows.
What if you find something?
Stop and photograph it before touching it. Place a ruler or coin beside the mark or insect for scale. Our guide on how to photograph an insect for identification explains lighting and angles.
If you find a live insect, trap it in a clear container or press clear tape over it. Our found a bug page explains how to keep a specimen safely. A dead or live insect is far more useful than a description.
Remember that many things resemble bed bugs. For instance, carpet beetle larvae are a common mix-up, and our comparison of bed bugs and carpet beetle larvae shows the differences. Bat bugs are another close lookalike, covered in bed bug vs bat bug.
What a mattress check cannot tell you
An empty mattress does not rule out bed bugs, because early or small infestations can leave little evidence, and bites alone are not reliable. The EPA notes that bite reactions vary between people, so marks on the skin cannot confirm anything.
If you have bites and are unsure what caused them, read our bites guide. The NHS says bites usually clear up within a week, and a pharmacist can advise if the itching persists.
However, one dark speck is not a diagnosis. Mould, dust and ordinary fabric dye can look similar at a glance. That is why we rely on several signs together, as explained on our methodology page.
Away from home and in rented homes
While travelling, the same method works on a hotel bed in a few minutes. Our guide to checking a hotel room for bed bugs gives a shorter routine. After a trip, see bed bugs after travel for how to check luggage.
For buying a bed or sofa second-hand, read about bed bugs in second-hand furniture before you bring it indoors. If you rent and find evidence, bed bugs in rented homes explains whom to tell and how to keep a record.
Next steps
Once you have inspected the mattress, use the five-question checker to weigh what you found. It runs in your browser and does not send your answers anywhere. It gives you a sense of how strong your evidence is. Therefore, it is a sensible next step before you spend money on anything.
If you have a specimen or a clear photo, head to found a bug to learn how to keep it. You can also ask a professional to confirm what you have through our contact page. They can look at your photos or a specimen and advise on next steps.
Questions and answers
How long does a mattress inspection take?
A careful check of the mattress, base and headboard needs enough time to go slowly along every seam. Rushing tends to miss the seams, which is where evidence collects.
Does a clean mattress mean there are no bed bugs?
No. A clean-looking mattress can still hold evidence in its seams, and bed bugs are found in homes regardless of cleanliness, according to the CDC.
What should I do if I find something dark on the mattress?
Photograph it with a ruler beside it and compare it with the signs guide. Do not scrub it away yet, because a clear photo or a saved specimen helps with identification.
Sources
We checked the facts in this article against these sources. However, this article supports triage, not diagnosis, so keep any specimen for an expert.