Horsefly bites are immediately noticeable due to the sharp, burning sensation they produce. Unlike mosquitoes that pierce the skin, the female horsefly uses serrated mouthparts to physically cut the skin open, creating a wound to feed on the resulting pool of blood. This traumatic feeding mechanism explains the initial intense pain and subsequent bleeding. The body’s reaction to the horsefly’s saliva, which contains an anticoagulant, causes a raised, red welt and localized swelling to develop rapidly.
Immediate First Aid Steps
The first action following a horsefly bite should focus on cleansing the wound to minimize the risk of secondary infection. Thoroughly wash the affected area with mild soap and clean water to remove any bacteria introduced by the fly’s mouthparts. The cutting action of the bite creates a significant breach in the skin barrier, making infection more likely.
Immediately following cleaning, apply a cold compress or ice pack wrapped in a thin cloth to the bite site for 10 to 20 minutes. Cooling the area restricts local blood flow, which reduces the initial pain and limits the extent of swelling. If the bite is on an extremity, elevating the limb can also assist in draining excess fluid and decrease puffiness.
Managing Pain, Itching, and Swelling
Addressing the discomfort and inflammation requires a targeted approach using over-the-counter medications.
Topical Treatment
For localized swelling and persistent itching, a mild topical corticosteroid cream, such as 1% hydrocortisone, can be applied directly to the welt. This type of cream works by suppressing the localized inflammatory response that causes redness and irritation.
Oral Antihistamines
Oral antihistamines are beneficial for managing the body’s systemic reaction to the bite, particularly widespread itching and residual swelling. Medications like cetirizine or diphenhydramine help block the effects of histamine released by the immune system, providing comprehensive relief. Follow the dosage instructions carefully, noting that some older-generation antihistamines may cause drowsiness.
Pain Relief
Simple oral pain relievers can be taken to manage the tenderness and discomfort associated with the bite. Nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, are suitable options because they address both pain and the inflammatory process. Acetaminophen is an alternative choice for pain relief, though it lacks the same anti-inflammatory properties.
Recognizing and Addressing Complications
While most horsefly bites resolve with home care, it is important to monitor the wound for signs that the injury is not healing correctly. A secondary bacterial infection may develop, often due to scratching, which introduces bacteria. Signs of infection include increasing pain, warmth, spreading redness or discoloration around the bite, or pus/drainage.
A more serious concern is a severe allergic reaction, which can manifest rapidly after the bite. Watch for symptoms that extend beyond the immediate bite area, such as generalized hives, dizziness, or swelling of the face, lips, tongue, or throat. Difficulty breathing or wheezing indicates a severe systemic reaction that warrants immediate medical attention. If these severe signs appear, calling emergency services or seeking urgent care is necessary.