Do Mosquitoes Bite Some People More Than Others? Blood Type and Body Chemistry

Short answer: yes, and it is mostly about how you smell rather than what blood type you are. Mosquitoes find you by following the carbon dioxide you breathe out, then close in on skin odour, warmth and moisture. Some people consistently produce a scent blend that is far more attractive than average, and that difference appears to be largely genetic and remarkably stable over time. The useful part is that the one factor you fully control — what you put on your skin — matters more than any of the traits you cannot change.

Key takeaways

• Being a mosquito magnet is real and measurable: in controlled trials, some people are landed on many times more often than others, and the same individuals stay attractive years later.
• Skin odour is the strongest known driver. A 2022 study in Cell linked high levels of skin-derived carboxylic acids — produced when skin bacteria feed on sebum — to being exceptionally attractive to Aedes aegypti.
• Carbon dioxide, body heat and sweat guide mosquitoes over the final few metres, which is why exercise, pregnancy and warm evenings all raise your odds.
• Blood type gets far more attention than the evidence supports: a few small laboratory studies, mixed results, and nothing you could change anyway.
• What actually works is behavioural and topical — cover exposed skin at dawn and dusk, remove standing water, and use a repellent with a proven active such as PMD or DEET.

How do mosquitoes choose a target?

Only female mosquitoes bite; they need a blood meal to develop eggs. They hunt in stages, and each stage uses a different sense.

1. Carbon dioxide — the plume from your breath can be detected from roughly ten metres away and tells a mosquito that a warm-blooded animal is nearby.
2. Body odour — as she gets closer, hundreds of volatile compounds coming off your skin decide whether you are worth approaching. This is where individual differences appear.
3. Heat, moisture and vision — in the last metre, skin temperature, humidity from sweat and visual contrast against the background guide the actual landing.

Because the difference between people is created almost entirely at the odour stage, the question of who gets bitten most is really a question about skin chemistry.

Skin bacteria and body odour

Your skin scent is not produced by you alone. Skin bacteria metabolise sebum and sweat, and the by-products are what a mosquito actually smells. In the 2022 Cell study, researchers at Rockefeller University asked volunteers to wear nylon sleeves and then tested mosquito preference between them. The most attractive participant drew around one hundred times more mosquitoes than the least attractive, and those rankings held up when the same people were retested years later. The chemical signature that separated them was the level of carboxylic acids on the skin — compounds produced by the skin microbiome.

That also explains why washing does not reset your status for long: the bacterial community rebuilds within hours, and the compounds come back with it.

Carbon dioxide, heat and sweat

Anything that increases your carbon dioxide output or raises your skin temperature makes you easier to find. Exercise does both, and it also deposits lactic acid and ammonia on the skin. Larger adults exhale more carbon dioxide than small children, which is part of why adults are often bitten first at a barbecue. A hot, humid evening keeps skin moist and volatile compounds evaporating, which is exactly the environment mosquitoes hunt best in.

Does blood type really matter?

This is the claim that circulates most and stands up least. A small number of laboratory studies — most often cited is a 2004 Japanese study on Aedes albopictus — reported more landings on people with type O blood than type A. The samples were small, the effect sizes modest, the results have not been consistently replicated, and no public health authority includes blood type in its bite-prevention guidance. Treat it as an interesting hypothesis, not a reason to expect more or fewer bites — and note that even if it were true, it is not a variable you can act on.

Genetics, pregnancy and alcohol

A 2015 twin study published in PLOS ONE found identical twins were more alike in how attractive they were to mosquitoes than non-identical twins, suggesting a meaningful heritable component to body odour and therefore to attractiveness. Pregnancy has been associated with increased attractiveness in field studies, plausibly because of higher exhaled carbon dioxide and slightly raised skin temperature. Alcohol is often blamed too; the evidence there is thin and comes from very small trials, though drinking outdoors on a warm evening does tend to coincide with peak biting hours and bare skin.

Clothing colour

In the final approach mosquitoes use vision, and they are drawn to dark, high-contrast shapes against a lighter background. Light, loose clothing is a genuinely useful adjustment — and long sleeves and trousers remove the target area altogether.

What the evidence actually supports

Things that will not fix it

• Garlic and vitamin B1. Repeatedly tested, repeatedly found ineffective as an oral repellent.
• Ultrasonic apps and wristbands. Reviews of the evidence have not found meaningful protection — we covered the trials in our guide to whether mosquito wristbands and ultrasonic apps work.
• Citronella candles alone. They can reduce landings in a small, still zone right beside the candle, but a breeze or a step away removes the effect.
• Applying repellent to clothing only. Mosquitoes will find the untreated ankles, wrists and hairline. Skin coverage is what counts.

How to be bitten less, whatever your body chemistry

• Apply repellent to all exposed skin — a missed patch is where you will be bitten. Reapply on the interval the label gives, and after swimming or heavy sweating.
• Cover up at dawn and dusk, when many biting species are most active, with long sleeves and light-coloured clothing.
• Shower and change after exercise to remove lactic acid, ammonia and sweat before you sit outside.
• Empty standing water weekly — plant saucers, gutters, buckets, paddling pools. Aedes mosquitoes breed in remarkably small volumes.
• Use a fan on a terrace. Mosquitoes are weak fliers and moving air also disperses your carbon dioxide plume.
• Use a bed net or screens where mosquito-borne disease is present, as the WHO advises for endemic regions.

How incognito® helps

You cannot rewrite your skin chemistry, but you can put a barrier of scent over it — and that is exactly what a repellent does. Our Insect Repellent Spray 100ml is built around PMD (para-menthane-3,8-diol), sold as Citrepel®, derived from Javanese citronella (Cymbopogon winterianus). PMD is the plant-based active that the CDC and EPA list alongside DEET among the ingredients effective against mosquitoes and ticks, so it is a DEET-free choice that is not a compromise on the active. It is clinically tested, vegan certified, biodegradable and made in the UK. If you want the chemistry behind it, our explainer on what PMD is and how it repels insects goes a level deeper. Whichever repellent you choose, cover every bit of exposed skin and follow the reapplication interval on the label — that single habit beats every trait on the list above.

FAQs

Do mosquitoes really bite some people more than others?
Yes. In controlled trials the difference between the most and least attractive people can be very large, and it stays consistent over years. Skin odour is the main reason.

Do mosquitoes prefer type O blood?
The evidence is weak. A few small laboratory studies reported more landings on type O volunteers, but the findings have not been reliably replicated and no health authority uses blood type in its advice.

Why do mosquitoes bite me and not my partner?
Most likely a difference in skin odour, driven by your skin bacteria, plus how much carbon dioxide and heat each of you gives off. Both of you should still use repellent.

Can I change how attractive I am to mosquitoes?
Not fundamentally. You can lower your odds by showering after exercise, wearing light long clothing at dusk and applying repellent to all exposed skin.

Does eating garlic or taking vitamin B keep mosquitoes away?
No. Both have been tested and neither works as an oral repellent. Topical repellents remain the option with evidence behind them.

Why do mosquitoes seem to bite ankles most?
Ankles and feet carry a distinctive bacterial odour and are the part people most often forget to treat or cover. Treat them deliberately.

Sources

• De Obaldia et al., Cell 2022 — Differential mosquito attraction to humans is associated with skin-derived carboxylic acid levels
• Fernández-Grandon et al., PLOS ONE 2015 — Heritability of attractiveness to mosquitoes
• CDC — Prevent mosquito bites
• EPA — Skin-applied repellent ingredients
• ECDC — Protective measures against mosquitoes
• WHO — Vector-borne diseases
• NHS — Insect bites and stings

This article is for general information only and is not medical advice. If a bite becomes badly swollen, infected or is followed by fever or a spreading rash, seek advice from a healthcare professional. Always use insect repellents as directed on the product label.