Horsefly Allergy Test
This page explains the horsefly allergy test, what it measures, and how to arrange it. The horsefly allergy test is a blood test used to check for an allergic sensitization to horsefly saliva proteins. It is typically ordered when a person has had a severe reaction after a horsefly bite, such as large swelling, hives, or difficulty breathing. The test helps a clinician assess whether symptoms are likely due to a horsefly allergy.
- Sample type
- blood
- Category
- Allergy
- Turnaround
- 1-3 business days
- Price
- $49
- Referral
- Not required
The horsefly allergy test is a blood test used to check for an allergic sensitization to horsefly saliva proteins. It is typically ordered when a person has had a severe reaction after a horsefly bite, such as large swelling, hives, or difficulty breathing. The test helps a clinician assess whether symptoms are likely due to a horsefly allergy.
What it measures
- Total IgE — A general measure of allergic antibody levels in the blood.
- Horsefly-specific IgE — Antibodies that bind specifically to horsefly saliva proteins.
- Other insect-specific IgE — Checks for cross-reactivity with similar insects like mosquitoes or deer flies.
- Serum tryptase (sometimes) — A marker that can help evaluate severe allergic reactions.
Who it is for
This test is usually ordered by an allergist or primary care clinician for people who have had unexplained allergic symptoms after horsefly bites. It may also be used when other insect allergies are suspected.
Preparation
No fasting or special preparation is needed. Tell your clinician about any medications you take, especially antihistamines, as they may affect test results.
Results and what they mean
Results are reported as a level of specific IgE, often graded from negative to strongly positive. A clinician interprets these numbers alongside your symptoms and history; a positive result alone does not confirm an allergy. This information is for general education only and is not medical advice.
How to order this test
- Choose the test and place a confidential order online.
- Select a certified collection site and pick a time that suits you.
- Have your specimen collected — most draws take only a few minutes.
- Review results in a secure portal, typically within 1–3 days.
Preparation, hours, and pricing vary by site; confirm details directly with the lab before your visit.
Availability by state
Direct-access online ordering for the horsefly allergy test is available in most states. It is currently unavailable in 6 states:
Everywhere else you can order confidentially and collect your sample at a certified site. Browse by state →
Frequently asked questions
Does a positive result mean I am definitely allergic to horseflies?
Not necessarily. A positive result shows sensitization, but only a clinician can determine if it explains your symptoms.
How long does it take to get results?
Most labs return results within 1 to 3 business days.
Can I take antihistamines before the test?
Antihistamines generally do not affect IgE blood tests, but check with your clinician first.
Is this test painful?
It uses a standard blood draw from a vein, which feels like a brief pinch.