Mosquito bite allergy
Marked local or, rarely, systemic reactions to mosquito bites.
About mosquito bite allergy
Mosquitoes are biting insects whose females feed on blood, and the familiar itchy bump is an immune reaction to proteins in their saliva. Sensitivity varies widely: some people react barely at all, while others develop marked itchy swellings, and children and those newly exposed to local mosquitoes sometimes react more strongly. Bites are more common in warm, humid conditions and near standing water, and typically occur on skin left uncovered outdoors, especially around dawn and dusk.
Reactions usually appear within minutes to hours as a red, itchy raised bump, sometimes with a larger surrounding swelling. Occasionally people develop bigger local reactions with more extensive swelling, warmth and redness, sometimes called skeeter syndrome, which can be mistaken for infection. Genuine whole-body allergic reactions to mosquito bites are rare. Scratching can break the skin and lead to secondary infection, and in some parts of the world mosquitoes can also transmit diseases, which is a separate consideration when travelling.
Management focuses on relieving the itch and protecting the skin. A pharmacist can suggest treatments to ease itching, and keeping the area clean and avoiding scratching help prevent infection. A GP can advise if a bite becomes infected or reactions are severe or persistent. Prevention is key: using insect repellent, covering exposed skin, and using nets or screens where mosquitoes are prevalent. A rare severe reaction with widespread swelling, breathing difficulty or collapse is a medical emergency requiring 999.
Common triggers
- Mosquito bite and products containing it
Symptoms
- Pain, redness and swelling at the sting or bite
- Widespread hives or itching
- Swelling of the face, lips or throat
- Wheezing or difficulty breathing
- Anaphylaxis in severe cases
Avoidance & management
- Avoid nests, hives and known habitats
- Wear covering clothing and avoid strong scents outdoors
- Use insect repellent and screens
- Carry an adrenaline auto-injector if prescribed
- Seek urgent help for a severe reaction
Sources & references
Allergy safety: what everyone should know
Mild-to-moderate reaction signs
- Itching, hives or a raised rash
- Swelling of lips, face or eyes
- Tingling mouth, sneezing, runny nose
- Stomach pain, nausea or vomiting
Anaphylaxis — call 999 (UK) or 112 (EU) immediately
- Difficult or noisy breathing, wheeze, persistent cough
- Swelling of the tongue or tightness in the throat
- Dizziness, collapse, pale and floppy (young children)
- Use an adrenaline auto-injector (e.g. EpiPen) at once if prescribed, then call an ambulance even if symptoms improve
Allergy or intolerance? A true allergy involves the immune system and can escalate quickly; an intolerance (e.g. lactose intolerance) is unpleasant but not life-threatening. The symptoms overlap, so self-diagnosis is unreliable.
Getting tested: home-testing kits based on IgG are not diagnostically valid. If you suspect an allergy, ask a GP for referral to an allergy clinic for skin-prick or specific-IgE testing and a supervised food challenge where appropriate.