What is the treatment for a mosquito bite?

Treatment of Mosquito Bites

For uncomplicated mosquito bites, apply cold compresses immediately to reduce pain and swelling, and use oral antihistamines for persistent itching—topical antihistamines should be avoided due to contact dermatitis risk. 1, 2

Immediate Symptomatic Treatment

First-Line Measures

• Apply cold compresses to the bite site immediately after being bitten to reduce local pain, swelling, and inflammation 1, 2
• Oral antihistamines (such as cetirizine or ebastine) are effective for reducing pruritus when topical measures are insufficient 2, 3, 4
• Prophylactic antihistamines can reduce immediate wheal reactions by approximately 57% within the first minute when taken before exposure 5, 3

What NOT to Do

• Avoid topical antihistamines as they significantly increase the risk of contact dermatitis and sensitization 2
• Do not wash the area with hot water, as this increases blood flow and worsens symptoms 2
• Do not prescribe antibiotics unless there is clear evidence of secondary bacterial infection (progressive redness, increasing pain, purulent discharge, or fever) 1, 2

Management of Large Local Reactions

For extensive swelling extending beyond the immediate bite site:

• Continue cold compresses and oral antihistamines 1, 2
• Consider a short course of oral corticosteroids for severe large local reactions, though evidence from controlled trials is limited 1, 2
• These reactions typically peak at 24-48 hours and can last up to one week 6

Emerging Treatment Options

Recent evidence suggests concentrated heat application (hyperthermia devices) may provide significant symptom relief:

• Reduces mosquito bite-induced itch by 57% within one minute and 81% within 5-10 minutes 5
• May be considered as an alternative or adjunct to traditional cold compress therapy 5

Prevention Strategies

Personal Protective Measures

• Use DEET-containing insect repellents on exposed skin—this is the most effective mosquito repellent available 1, 2
• Apply DEET sparingly and avoid high-concentration products on children 1, 2
• Wear long-sleeved clothing and long pants, especially during evening hours when mosquitoes are most active 6, 1, 2
• Apply permethrin to clothing for additional protection 6, 1, 2
• Use mosquito nets impregnated with pyrethroids (permethrin 0.2 g/m² every 6 months) when sleeping in areas where mosquitoes cannot be excluded 6
• Stay in well-screened or air-conditioned accommodations 6, 1

Ineffective Prevention Methods

• Electronic buzzers marketed as repellents are not effective and should not be relied upon 6

When to Escalate Care

Systemic Reactions (Rare but Serious)

While systemic reactions to mosquito bites are very rare 7, immediate recognition is critical:

• Refer to an allergist-immunologist if the patient has experienced any systemic reaction 1
• Patients with history of systemic reactions should carry emergency epinephrine (0.01 mg/kg, up to 0.3 mg in children, 0.3-0.5 mg in adults) 1
• Treat acute systemic reactions as anaphylaxis with injectable epinephrine, supportive therapy, and emergency transport 1
• Fatal reactions are associated with delayed epinephrine administration—do not hesitate 1

Common Pitfalls to Avoid

• Misdiagnosing normal inflammatory reactions as secondary bacterial infections and unnecessarily prescribing antibiotics 2
• Using topical antihistamines despite their known risk of contact sensitization 2
• Failing to recognize the rare but potentially life-threatening systemic reactions 1, 2
• Relying on ineffective prevention methods like electronic devices 6