Flea bites

Flea bites on humans: what they look like and what to do

How to recognise flea bites on people, why they are nearly always on the ankles, simple first aid, when to see a doctor, and how to find the fleas causing them.

The short answer

Flea bites are small, very itchy red bumps, usually around the ankles and shins and sometimes at the waistband, often several close together. They normally fade by themselves over a few days. In New Zealand the cat flea is almost always responsible, and it bites people without living on them, so the bites stop only once the fleas in the house are dealt with, which is what treating fleas in the house is for.

What do flea bites look like on humans?

A flea bite is a small raised red bump, a few millimetres across, with a tiny darker red point in the middle where the flea fed and a paler red halo around it. It itches far more than its size suggests, and bites usually turn up several at a time, close together, rather than one on its own.

In people who have become sensitised to flea saliva the reaction is bigger. The bite swells, a small blister can form in the centre, and if it breaks it weeps and then crusts over. Some people also get a puffy, hive-like reaction around the bite, and a strong reaction can stay itchy for longer than the usual few days.

There are no photographs on this site, so the description has to do the work: small, red, intensely itchy, clustered, and low on the body. If what you are looking at fits all five, fleas are the first thing to rule in or out.

Where fleas bite, and why it is nearly always the ankles

Fleas live in the floor covering and jump onto whatever passes, so bites cluster on the feet, ankles and lower legs, the height a flea can reach from the carpet. The other common spot is the waistband, where a gap between shirt and trousers lets a flea that has climbed up reach skin. Bites much higher up usually mean an animal is sleeping on a bed or sofa and the fleas are coming from there.

Cat and dog fleas would rather feed on the animal, and they turn to people mainly when they are hungry and no animal is around. That is why the worst bites so often follow a holiday: the house sat empty, the fleas waited in their cocoons, and the vibration and warmth of the family walking back in brought them out at once, all of them looking for a meal.

Flea bite, or something else?

A few clues point firmly at fleas: the bites are at ankle height, they appear during the day as well as overnight, there is a cat or dog in the house now or there was recently, and black specks from the pet's bedding turn red when you press them onto damp white paper. If the bites are on the arms and upper body, appear only after a night in bed and there is no animal, the pattern points away from fleas, and how bed bug bites differ is worth reading next.

The other usual suspects are mosquitoes, which bite whatever skin is uncovered at the time, mites from a bird nest in the roof space, and skin conditions such as hives, which can look like bites but are not. If nothing in the house explains it, your GP is the right person to ask.

Can fleas live on humans?

Not in the way they live on a cat. Cat and dog fleas bite people when they have gone without a meal, then drop off, because we do not have the fur they need to hold on, hide and lay eggs in. A flea that bites you has come from the floor or the furniture, and it will go back there.

There is a true human flea, Pulex irritans, but Health New Zealand describes it as rare here, while cat fleas are very common. In practice, almost every case of fleas biting people in an Auckland home is a cat flea problem, whether or not anyone in the house owns a cat.

How to treat flea bites

Wash the bites with soap and water, hold a cold cloth or a wrapped ice pack on them if they are swollen, and try hard not to scratch, because broken skin is what lets a bite become infected. For the itch, pharmacists commonly suggest antihistamines, or a low-strength hydrocortisone cream; check with them before using either on a child, in pregnancy or alongside other medicines.

Home remedies such as menthol rubs, toothpaste or baking soda paste come up often. There is little evidence that they help, and some can sting or irritate skin that has already been scratched open, so a cold compress and the pharmacist's advice are the better bet. Keep fingernails short, especially on children, while the bites heal.

How long do flea bites last?

A single flea bite usually settles within a few days, a little longer if it has been scratched or if you react strongly to flea saliva. What does not fit that pattern is a steady supply of new bites. Fresh bites appearing every day are not slow healing, they are new feeding, and they tell you the fleas are still active in the house.

At that point the useful step is to find where they are breeding, using the signs of fleas in the house: flea dirt in the pet's bedding, adults jumping onto white socks, and the rooms where the bites happen most.

When to see a doctor about flea bites

See your GP or a pharmacist if a rash develops around the bites, or if they show signs of infection: redness that spreads, warmth, increasing pain, pus or yellow crusting, small pus-filled spots, or a fever. Infected bites sometimes need antibiotic treatment, which is a decision for a doctor. Healthline is free to call at any hour on 0800 611 116 if you are unsure whether to go in.

Serious allergic reactions to flea bites are rare. Call 111 straight away if anyone has a swollen face, lips or throat, difficulty breathing or feels faint after being bitten.

Can flea bites make you ill?

For almost everyone in New Zealand the harm from flea bites is the itch, and the risk of a skin infection from scratching. There are two sourced exceptions worth knowing about, and both are uncommon. The first is the flea tapeworm, Dipylidium caninum, which can be passed on if an infected flea is swallowed, so it is most relevant to small children who play on the floor with a pet that has fleas.

The second is murine typhus, spread by infected cat and rat fleas or their droppings getting into a bite. Health New Zealand records it as present in some parts of the country and as a notifiable disease, so if you become unwell after a stretch with fleas or rats around the house, tell your doctor about them. Plague is what fleas are known for historically, and Health New Zealand's current advice on household fleas is about bites and tapeworm. Lyme disease is spread by ticks, not fleas.

Stopping the bites means finding the fleas

The bites will heal, but the eggs and cocoons in the carpet do not go anywhere, and every adult that hatches from them is another bite. So the lasting fix is in the house, not on your skin. Start by looking where the animal sleeps and rests: its bedding, the patch of sun by a door, the base of the sofa and the hallway it walks along. Walking slowly through carpeted rooms in white socks pulled high will often show you adult fleas against the fabric.

From there you have two routes. You can do the whole job yourself, properly and in order, by getting rid of fleas in the house, step by step, which works well when the problem is caught early. Or you can have the house treated, with the pet looked after by your vet the same week, which is the faster route when the whole house is affected or an animal is living under the floor.

Questions

Flea bite questions

Do fleas bite humans in bed?

They can, if an animal sleeps on the bed, because flea eggs drop into the bedding there and the adults that hatch bite whoever lies down. Hot wash the sheets and vacuum the mattress and the carpet beside the bed. Without a pet in the house, bites that only ever happen in bed are less likely to be fleas and more likely to be something living in the bed itself.

Why is only one person in the house getting bitten?

Usually everyone is being bitten, but people react very differently. Someone sensitised to flea saliva gets large, itchy bumps, while someone else may barely mark at all. Where you spend your time matters too: the person who sits on the floor with the dog, or walks about barefoot, gives the fleas the most chances.

I have flea bites but no pets. How?

The usual answers are a previous occupant's cat or dog, whose fleas waited as cocoons until you moved in, or an animal using the space under the house, such as a neighbour's cat or rats. Fully formed fleas can wait in their cocoons for months. Check the subfloor vents and under any deck for signs of an animal sleeping there.

Is a sand flea bite in New Zealand a flea bite?

Usually not. In New Zealand people who say sand flea almost always mean the sandfly, or namu, a tiny biting black fly of the genus Austrosimulium whose larvae live in streams, so it is common near water and bush. It is a fly, not a flea, though the same first aid applies: wash, cool, and do not scratch.

How can I stop fleas biting me while the house is treated?

Cover the lower legs, which is where fleas reach: long socks pulled up over your trousers help. An insect repellent containing DEET or picaridin on exposed skin also reduces bites. Keep vacuuming every day, because it brings the remaining fleas out onto the treated floor sooner, and the bites drop away as they die.

Can flea bites spread to other people?

No. Flea bites are not contagious and cannot be passed from one person to another; the fleas in the house are the only source. A bite that has been scratched open can become infected, so keep nails short, keep the skin clean, and see a doctor if a bite gets hot, painful or starts to weep.