What is the treatment for a bug bite?

Bug Bite Treatment

For most bug bites, apply cold compresses and oral antihistamines immediately—no antibiotics are needed unless there is clear evidence of secondary bacterial infection. 1, 2

Immediate Management by Reaction Type

Simple Local Reactions (Most Common)

Most insect bites require minimal intervention and resolve spontaneously. 1

• Apply cold compresses or ice packs to the affected area to reduce pain and swelling 2, 3
• Give oral antihistamines (e.g., diphenhydramine, cetirizine) to reduce itching and discomfort 1, 2, 3
• Consider oral analgesics (acetaminophen or ibuprofen) for pain relief 2, 3
• Apply topical corticosteroids (e.g., hydrocortisone 1%) directly to the bite site for local inflammation and itching 3, 4
• No treatment may be necessary for mild reactions that cause only transient redness and swelling 1

Large Local Reactions (Extensive Swelling >10 cm)

These reactions peak at 24-48 hours and can last 5-10 days, but are caused by allergic inflammation, not infection. 1, 5

• Continue cold compresses and oral antihistamines as first-line therapy 2, 3
• Initiate a short course of oral corticosteroids promptly (within the first 24-48 hours) to limit progression of swelling in severe cases 1, 3
• Do NOT prescribe antibiotics unless there is clear evidence of secondary bacterial infection (purulent drainage, fever, progressive worsening beyond 48-72 hours) 1, 2, 5

Systemic Reactions/Anaphylaxis (Life-Threatening Emergency)

Administer intramuscular epinephrine immediately—this is the ONLY first-line treatment for anaphylaxis. 1, 3

• Give epinephrine 0.01 mg/kg (maximum 0.3 mg in children, 0.3-0.5 mg in adults) into the anterolateral thigh 3
• Activate emergency medical services immediately and transport to an emergency department 1, 3
• Be prepared to repeat epinephrine if symptoms persist or recur 3
• Provide supportive therapy including airway management, IV fluids, and cardiac monitoring as needed 1
• Antihistamines and corticosteroids are NOT substitutes for epinephrine and play no role in acute anaphylaxis management 3

Critical Pitfalls to Avoid

• Never delay epinephrine administration in anaphylaxis to give antihistamines first—fatal sting reactions are associated with delayed epinephrine 1, 3
• Do not misdiagnose allergic swelling as cellulitis—the extensive erythema, swelling, and even lymphangitis are caused by mediator release, not bacterial infection 1, 5
• Antibiotics are not indicated for routine bug bite swelling, as this represents allergic inflammation rather than infection 1, 2, 5
• Secondary infection is uncommon following insect bites and should only be treated if there is purulent discharge, fever, or progressive worsening beyond 48-72 hours 2, 5

Special Considerations

Fire Ant Stings

• A sterile pseudopustule develops within 24 hours and is pathognomonic for fire ant stings 1
• Leave the vesicle intact and keep it clean to prevent secondary infection—the vesicle contains necrotic tissue, not pus 1
• Do not routinely prescribe antibiotics, as secondary infection is unusual 1

Stinger Removal (Bees)

• Remove the stinger within 60 seconds by scraping or plucking—speed matters more than method 3
• Wash the area with soap and water after removal 3

Post-Treatment and Prevention

• Prescribe an epinephrine autoinjector for any patient who experiences a systemic reaction and provide training on self-administration 1, 3
• Refer to an allergist for venom-specific IgE testing and consideration of venom immunotherapy (VIT) in patients with systemic reactions 1, 2
• VIT reduces the risk of future systemic reactions from 25-70% to nearly zero in appropriate candidates 1
• Educate on avoidance measures: avoid bright clothing and scented products, be cautious around outdoor eating areas, and have known nests removed professionally 2