Buffalo gnat bites are unusually painful compared to other insect bites, and they can itch and swell for days or even weeks. The good news is that most bites respond well to simple at-home care: clean the area, apply cold, and use over-the-counter products to control the itch and swelling.
Why Buffalo Gnat Bites Hurt More
Buffalo gnats (also called black flies) don’t pierce the skin like mosquitoes. They slice it open with blade-like mouthparts, then feed on the pooling blood. This tearing action is what makes the initial bite so painful, and it often leaves a small bleeding wound at the center of the bite. The fly’s saliva contains compounds that prevent clotting and trigger a strong inflammatory response, producing swelling, redness, and intense itching that can persist far longer than a typical mosquito bite.
Symptoms commonly last for several days, but some people develop persistent skin reactions (raised, discolored, swollen bumps) that can linger for weeks or even months. Knowing this timeline is helpful so you don’t panic if a bite still looks angry after a week.
Immediate First Aid
As soon as you notice a bite, move away from the area where you were bitten. Buffalo gnats swarm, and staying put invites more bites. Then follow these steps:
- Wash the bite gently with soap and water to remove saliva residue and reduce infection risk.
- Apply cold using a cloth dampened with cold water or wrapped around ice. Keep it on for 10 to 20 minutes. This constricts blood vessels, which limits swelling and dulls pain.
- Elevate the area if the bite is on an arm or leg. This helps fluid drain away from the swollen tissue.
Resist the urge to scratch. Buffalo gnat bites itch intensely, but scratching breaks the skin further and opens the door to bacterial infection.
Over-the-Counter Itch and Swelling Relief
For most people, the hardest part of a buffalo gnat bite is managing the itch. A layered approach works best, combining something on the skin with something taken by mouth.
Topical Options
A medium-strength hydrocortisone cream (1%, available without a prescription) applied directly to the bite two to three times a day is one of the most effective ways to calm inflammation and itching. Calamine lotion is another solid choice, especially if you have multiple bites. It cools the skin on contact and reduces the urge to scratch. You can alternate between the two if one alone isn’t enough.
For a simple home remedy, mix baking soda with a small amount of water to form a thick paste and apply it to the bite for about 10 minutes before rinsing it off. This can provide temporary relief between applications of hydrocortisone.
Oral Antihistamines
An oral antihistamine helps control itching from the inside, which is especially useful at night when scratching in your sleep can make things worse. Non-drowsy options like cetirizine (Zyrtec) work well for daytime use. If the itching is disrupting your sleep, diphenhydramine (Benadryl) has a sedating effect that can actually work in your favor at bedtime. Over-the-counter pain relievers like ibuprofen can also help reduce both swelling and discomfort.
For bites that stay severely swollen and itchy despite these measures, a doctor may prescribe a short course of oral corticosteroids to bring the inflammation under control more aggressively.
Black Fly Fever
Some people, particularly those bitten multiple times in a single outing, develop a cluster of whole-body symptoms known as black fly fever. This includes headache, nausea, fever, and swollen lymph nodes in the neck. It’s a reaction to the volume of fly saliva introduced into the body, not an infection. Black fly fever is uncomfortable but generally resolves on its own within a few days. Rest, fluids, and over-the-counter pain relievers typically manage the symptoms.
Signs of Infection
Because buffalo gnats create an open wound rather than a tiny puncture, their bites carry a higher risk of secondary bacterial infection than most insect bites. Watch for these warning signs in the days after a bite:
- Increasing warmth and redness spreading outward from the bite
- Worsening pain rather than gradual improvement
- Pus or cloudy drainage from the wound
- Red streaking on the skin near the bite
- Fever or chills
A growing area of redness and warmth could indicate cellulitis, a skin infection that requires antibiotic treatment. If the rash is expanding but you don’t have a fever, get it evaluated within 24 hours. If it’s spreading rapidly or you develop a fever, seek care right away.
Severe Allergic Reactions
True anaphylaxis from buffalo gnat bites is rare, but it does happen. The allergenic proteins in black fly saliva can trigger a life-threatening reaction in sensitized individuals. Call 911 immediately if you notice any of these symptoms after being bitten:
- Hives or itching spreading well beyond the bite site
- Swelling of the face, throat, or tongue
- Difficulty breathing, wheezing, or chest tightness
- Dizziness or a rapid drop in blood pressure
- Nausea, vomiting, or stomach cramps
If you’ve had a severe reaction to black fly bites before, carrying an epinephrine auto-injector during peak season is a reasonable precaution to discuss with your doctor.
Preventing Bites in the First Place
Buffalo gnats are most active during daylight hours, particularly in late spring and early summer near running water where they breed. They’re attracted to dark colors, carbon dioxide, and perspiration. A few practical strategies can dramatically reduce your exposure.
Repellents containing 20% picaridin have been tested specifically against black flies and provide roughly 10 hours of protection per application, whether in cream or spray form. DEET-based repellents also work, though head-to-head comparisons with picaridin specifically for black flies are limited. Apply repellent to all exposed skin, not just arms and legs, since buffalo gnats target the head, neck, and ears.
Clothing matters as much as repellent. Wear light-colored, long-sleeved shirts and long pants. Tuck pant legs into socks. A hat with a fine mesh head net is the single most effective barrier if you’re working or hiking in a heavy swarm area. Buffalo gnats tend to crawl under loose clothing edges, so snug cuffs and collars help. Permethrin-treated clothing adds another layer of protection, especially for people who spend extended time outdoors during peak season.