Infected mosquito bite: what to do

An infected mosquito bite usually refers to a local reaction that goes beyond ordinary redness: the area becomes hot, painful and swollen, sometimes with pus present. This may be a secondary bacterial infection – often caused by Staphylococcus aureus or Streptococcus pyogenes – linked to repeated scratching. The term also covers the direct transmission of a pathogen via the insect’s saliva: the dengue virus, the malaria parasite, or even filarial worms responsible for filariasis. The infection in question may thus be either cutaneous and localised, or systemic following the spread of the infectious agent. 

Here we outline the main causes of infected mosquito bites: 

Bacterial secondary infection following scratching: scratching breaks the skin’s barrier, allowing bacteria already present on the skin to penetrate deeper and trigger impetigo or an abscess.

Virus transmission (arboviruses): dengue, chikungunya, Zika, yellow fever...these infections begin when the mosquito transmits the virus during a bite.

Parasitic diseases: malaria is caused by a parasite (Plasmodium) injected by the Anopheles mosquito. It migrates to the liver firstm before invading the red blood cells. 

Prolonged immuno-allergic reactions: in people with atopic conditions, a single bite can trigger severe and persistent swelling. This then facilitates bacterial infection.

Below are some signs that should make you suspect an infected mosquito bite: 

• Redness extending beyond 5 cm: a sign of progressive inflammation

• Heat and throbbing pain: indicative of a deep inflammatory process

• Firm or fluctuating swelling: an abcess forming

• Yellowish or bloody discharge: impetigo or a mature abscess

• Fever ≥ 38 °C: possible systemic spread

• Red streak following the direction of a blood vessel: lymphangitis, medical emergency.

If you experience any of these symptoms, you should seek immediate medical attention, particularly in children, pregnant women or immunocompromised individuals.

How can you recognise an allergic reaction to a mosquito bite?

An allergy occurs within hours of the bite. It is characterised by a swollen patch, sometimes larger than 10 cm, intense itching and, rarely, hives. The swelling typically subsides within two days, unless excessive scratching perpetuates the irritation. Systemic symptoms (dizziness, breathing difficulties) are rare but require urgent medical attention: these could suggest anaphylactic shock. Hives, also known as urticaria, is rash of red, itchy, temporary patches caused by the release of histamine from skin mast cells. 

What diseases does the tiger mosquito carry?

The tiger mosquito (Aedes albopictus) is a recognised vector for several arboviruses, or viral diseases transmitted by insects. It can transmit three major infections: chikungunya, dengue and the Zika virus. These diseases are common in tropical regions, but can also occur as autochthonous cases – that is, contracted locally without any history of travel – if an infected person is bitten by a mosquito that subsequently becomes a vector. Transmission can occur regardless of whether the mosquito carrying the virus is infected or not. Chikungunya causes severe joint pain; dengue can lead to haemorrhagic fever; and Zika is feared for its neurological complications and risks for unborn children. Please note: Aedes albopictus does not transmit malaria, which is carried by a different mosquito (the genus Anopheles). Prevention relies on controlling mosquito breeding and on personal protection against bites.

Our suggestions for natural remedies to prevent and relieve bites: 

Mosquito repellent for adults and children : Aroma-Zone’s mosquito and tick repellent spray features a plant-based formula suitable for babies from 6 months, children and adults. It contains 30 per cent of an active ingredient derived from citronella in a hydroalcoholic base without a propellant, and has a mild grapefruit scent. Independent tests demonstrate effectiveness for up to 7 hours against tiger and common mosquitoes, and up to 6 hours against tropical mosquitoes. The 75 ml aluminium bottle, which is convenient to carry, is largely recyclable. Precautions for use recommend not spraying directly onto the face, avoiding contact with the eyes, and advise against use by pregnant or breastfeeding women.

Discover our mosquito repellent for adults and children

Mosquito and tick repellent stick : the Aroma-Zone mosquito and tick repellent stick is also formulated using a plant-based active ingredient derived from lemongrass, contains no neurotoxic insecticides, and has a mild fragrance reminiscent of grapefruit. This solid, compact format allows for precise, localised application without coming into contact with the hands or eyes, making it ideal for children aged 6 months and over. Tested by an independent laboratory, it provides up to 5 hours’ protection against common mosquitoes and ticks, and up to 4 hours’ protection against tiger and tropical mosquitoes. The 20 g stick comes in a recycled cardboard case containing over 40 % recycled material. The recommended use is 1 to 3 applications per day depending on age, avoiding the face and reapplying after swimming or sweating.

Discover our Mosquito and Tick Repellent Stick:

Soothing essential oil roll-on for insect bites : The rsoothing aromatherapy roll-on is a 100 % natural product, certified Cosmos Organic, designed to quickly relieve itching caused by insect or plant stings. It combines organic essential oils of true lavender and chamomile (Roman and German), calendula extract and organic menthol crystals, providing an immediate cooling and soothing effect. Suitable for adults and children aged 3 and over, this 5 ml roll-on in a glass bottle with a steel ball is convenient to carry around. It is recommended that pregnant or breastfeeding women avoid using this product, and that it be stored away from heat and light. 

Discover our Soothing Essential Oil Roll-on for Insect Bites :

To avoid any infected mosquito bites and complications, we advise you to:

1. Clean the bite immediately: with lukewarm water and mild soap within two minutes of being bitten

2. Disinfect: using an alcohol-free antiseptic solution morning and evening for 48 hours

3. Cool the area: you can use a wrapped ice pack for a maximum of 10 minutes to reduce swelling

4. Avoid scratching: if the itching becomes unbearable, gently tap the area

5. Monitor: mark the edge of the redness with a pen; if it spreads beyond this mark within 24 hours, seek medical advice

6. Prevent future bites: wear covering clothing, fit a mosquito net, and use an approved bug repellent. 

Any systemic symptoms (persistent fever, joint pain, severe headaches) following a bite from an infected mosquito require prompt medical attention, as the bite may be a sign of a generalised infection or an arbovirus infection. 

An infected mosquito bite often remains harmless if it is cleaned and monitored from the outset. Keeping the skin clean, minimising scratching and using approved soothing treatments helps to contain the local reaction. In Europe, the real threat lies mainly in the viruses carried by the tiger mosquito, hence the need for strict repellent measures, particularly at dawn and dusk, when Aedes females are most active. If in doubt, it is best to consult a healthcare professional to ensure early treatment and avoid any complications. 

Stéphanie is a pharmacist (since 2010) and holds a PhD in molecular biology (since 2012). Passionate about writing, she has produced medical content for nearly 15 years. Her goal is to make information accessible and easy to understand, without ever sacrificing scientific accuracy.