Beta Lactoglobulin (BLG) Allergy Test
Below is a plain-language overview of the beta lactoglobulin (blg) allergy test. The beta lactoglobulin (BLG) allergy test is a blood test that checks for allergic sensitization to beta lactoglobulin, a major protein found in cow's milk. It is usually ordered when a person has symptoms after drinking milk or eating dairy, such as hives, stomach upset, or breathing changes, and the cause is unclear.
- Sample type
- blood
- Category
- Allergy
- Turnaround
- 1-3 business days
- Price
- $49
- Referral
- Not required
The beta lactoglobulin (BLG) allergy test is a blood test that checks for allergic sensitization to beta lactoglobulin, a major protein found in cow's milk. It is usually ordered when a person has symptoms after drinking milk or eating dairy, such as hives, stomach upset, or breathing changes, and the cause is unclear.
What it measures
- Beta lactoglobulin-specific IgE — Antibodies that can attach to this milk protein and trigger allergy symptoms.
- Total IgE — A general measure of allergic antibody level, sometimes used for context.
- Other milk protein IgEs — Tests for related proteins such as alpha-lactalbumin or casein may be added.
- Cross-reactive allergen panel — Checks for similar proteins in goat or sheep milk that may also react.
Who it is for
This test is typically ordered by primary care clinicians, pediatricians, or allergists. It may be used when a milk allergy is suspected or to help track a known milk allergy over time.
Preparation
No fasting or special preparation is needed for this blood test. Tell your clinician about any medications you take, because some antihistamines can affect allergy test results.
Results and what they mean
Results are reported as a level of specific IgE, often grouped as negative, low, moderate, or high, along with a reference range from the lab. A clinician interprets these numbers together with your symptoms and history. This is general information only and is not medical advice; discuss your results with a qualified clinician.
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 beta lactoglobulin (blg) 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 allergic to milk?
Not always. A positive result shows sensitization, which may or may not cause symptoms. Your clinician uses your history to decide what it means.
Do I need to stop eating dairy before the test?
No. The test measures antibodies in your blood, so avoiding or eating dairy beforehand does not change the result.
Can this test tell me how severe a reaction will be?
No. It cannot predict how severe a future reaction might be. Your clinician assesses that based on your symptoms and history.
How long until results are ready?
Results are usually available within 1 to 3 business days, though timing can vary by lab.