Alpha-gal syndrome (AGS) is an allergic condition that develops after a tick bite and shows up later as an allergic reaction to red meat. Names used interchangeably in the literature: mammalian meat allergy, red meat allergy, tick-bite meat allergy. The Centers for Disease Control and Prevention has flagged it as significantly under-recognized in U.S. healthcare. Reactions can be fatal.

Between 2010 and 2022, CDC and commercial-laboratory analyses identified well over 110,000 positive alpha-gal sIgE results consistent with suspected AGS across overlapping time windows. The 2017 to 2022 MMWR analysis specifically identified 90,018 people with positive results during that period. CDC notes that AGS is not nationally notifiable, so the true number is unknown, and an adjusted prevalence model suggests roughly 96,000 to 450,000 people in the U.S. may have developed AGS.

The main blood test used in an AGS evaluation is a serum alpha-gal-specific IgE test. It can show whether alpha-gal IgE antibodies are measurable, but it does not diagnose AGS by itself. Quest Diagnostics test code 10554. Labcorp test code 650001.

What this test can and cannot do

What it can do:

Detect alpha-gal-specific IgE antibodies in serum
Provide a numerical value (in kU/L) that a clinician can interpret with your history
Help an evaluation of unexplained allergic-type symptoms after mammalian product exposure

What it cannot do:

Diagnose AGS by itself
Predict how severe a future reaction will be
Identify every food, medication, vaccine, or product an individual personally needs to avoid
Replace emergency care for an allergic reaction
Test for Lyme disease, ehrlichiosis, Rocky Mountain spotted fever, or other tick-borne infections

What alpha-gal syndrome actually is

Galactose-alpha-1,3-galactose, called alpha-gal for short, is a carbohydrate epitope found on the glycoproteins and glycolipids of most non-primate mammals. It appears in beef, pork, lamb, venison, rabbit, bison, and other mammalian meat. It is also present in cow's milk and many dairy products, in gelatin (which is rendered from mammalian connective tissue), and in some pharmaceutical and medical products that use mammalian sources or mammalian cell lines.

Humans, apes, and Old World monkeys do not produce alpha-gal, which is one reason the human immune system can recognize it as foreign. Most people do not develop an IgE-mediated allergic response to alpha-gal after eating mammalian products. After certain tick bites, some people develop alpha-gal-specific IgE antibodies. Once those antibodies exist in circulation, eating mammalian meat or consuming mammalian-derived products can trigger an allergic reaction.

This makes AGS structurally distinct from most food allergies, which usually develop in early childhood and respond to a protein. AGS most often develops in adulthood, in a person who has eaten red meat without incident for years, and the trigger is a sugar. Children can also develop AGS, though it is less commonly described. A child with delayed hives, vomiting, abdominal pain, breathing symptoms, or fainting after mammalian food exposure should be evaluated by a pediatric clinician or allergist.

The tick connection

In the United States, the lone star tick (Amblyomma americanum) is the primary vector for alpha-gal sensitization. The tick is named for the single white spot on the back of the adult female. It is an aggressive feeder active from spring through fall.

The mechanism is still being characterized, but the prevailing model is that lone star tick saliva contains alpha-gal or alpha-gal-like molecules, and the bite delivers them in a way that primes the immune system to produce IgE antibodies against alpha-gal. Subsequent bites can boost that response.

Other tick species have been associated with AGS outside the U.S.: castor bean ticks in Europe, paralysis ticks in Australia, and several species in Asia and Africa have all been linked to alpha-gal sensitization in published cases. Within the U.S., the lone star tick is the dominant association, though published case reports describe AGS following Ixodes scapularis bites in Maine and Ixodes pacificus bites in Washington state. These extra-range cases appear rare. AGS is most strongly associated with lone star ticks in the southern, midwestern, and mid-Atlantic United States, and lone star tick range has been pushing north into the Mid-Atlantic and the Ohio Valley, west into the Plains states, and into parts of New England. Geography should inform the differential rather than rule AGS in or out by itself.

A very itchy tick bite can occur before AGS develops, but a spreading red rash, fever, severe headache, body aches, facial weakness, or other acute illness after a tick bite should be evaluated for other tick-borne diseases. An alpha-gal IgE test does not test for Lyme disease or other tick-borne infections.

How alpha-gal syndrome shows up

The hallmark feature of AGS is delayed onset. Most food allergies cause symptoms within minutes. Alpha-gal reactions typically begin 2 to 6 hours after mammalian meat or product consumption, sometimes up to 8 hours, with shorter or longer windows in some cases.

A leading explanation for the delay is that alpha-gal-bearing glycolipids are absorbed with dietary fats, packaged into chylomicrons (large lipoprotein particles), and transported through the lymphatic system before entering the bloodstream via the thoracic duct. Alpha-gal-bearing glycoproteins may also contribute. The mechanism is best described as an active area of research rather than a closed explanation, but the chylomicron model helps explain why symptoms often begin hours after eating, when the meal is long over and the person may be asleep, exercising, or somewhere unrelated to where they ate.

Cofactors that can lower the reaction threshold: alcohol, exercise, NSAIDs, and high-fat meals are documented AGS-specific cofactors. Other factors recognized in food allergy generally (viral illness, sleep deprivation, hormonal cycle) may also contribute. A person may tolerate a food once and react another time because cofactors changed. A symptom and food diary can help a clinician interpret the pattern.

Symptoms vary widely. Common presentations include:

Hives, itching, flushing, or rash
Swelling of the lips, face, tongue, or throat
Nausea, vomiting, abdominal pain, or diarrhea
Heartburn or indigestion
Shortness of breath, wheezing, or cough
Drop in blood pressure, dizziness, or fainting
Anaphylaxis, which can be fatal

Gastrointestinal symptoms without skin involvement occur often enough that AGS is frequently misdiagnosed as irritable bowel syndrome, gallbladder disease, food intolerance, or “idiopathic” symptoms. The CDC has documented misdiagnosis as gastrointestinal disease, idiopathic urticaria, idiopathic anaphylaxis, and neuro-psychiatric conditions in the published literature.

Severity is not predictable from one reaction to the next. A person who has only had hives can experience anaphylaxis on a subsequent exposure. A well-documented fatal case of delayed anaphylaxis after mammalian meat consumption has been reported, and fatal alpha-gal-mediated reactions to medical products have also been described. Severe delayed symptoms, including severe abdominal pain, should be treated as clinically urgent rather than waited out.

Patterns that may warrant discussing alpha-gal testing with a clinician

Patterns in the published literature that have been associated with AGS include:

Unexplained allergic-type reactions (hives, swelling, GI distress, anaphylaxis) without a clear identified trigger
Reactions that recurrently occur in the evening or overnight, hours after dinner
Reactions that began in adulthood in someone who has eaten red meat and dairy without incident for years
A history of tick bites, especially lone star tick bites, particularly if the bite area was unusually itchy
Living in or traveling through the southern, mid-Atlantic, or midwestern U.S. with unexplained allergic symptoms
Unexplained reactions to medications, surgical procedures, or contrast agents that may have contained mammalian-derived components

AGS sits on the differential for unexplained recurrent allergic-type episodes in adults who consume mammalian products, including patients previously diagnosed with IBS, GERD, idiopathic urticaria, or anxiety where those diagnoses do not fully explain the symptom pattern. A clinician can evaluate whether an alpha-gal IgE test is appropriate for an individual situation.

A recent tick bite alone does not necessarily mean alpha-gal IgE testing is useful. Testing is most clinically meaningful when there are delayed allergic-type symptoms after mammalian food or product exposure, or when a clinician is evaluating unexplained allergic episodes.

When to prioritize clinical care over standalone testing

Some situations are better served by clinician evaluation before or instead of standalone lab testing:

Breathing symptoms, fainting, throat swelling, severe abdominal pain, repeated vomiting, severe diarrhea, or anaphylaxis
Reactions after medications, vaccines, or medical procedures
Pregnancy, suspected pregnancy, or breastfeeding
A child with possible symptoms
An upcoming surgery, hospitalization, vaccination, or implanted medical product
Asthma, mast-cell disorders, prior anaphylaxis, or severe reactions involving breathing, fainting, or multiple body systems
Use of beta-blockers, ACE inhibitors, anticoagulants, cancer therapy, or immune-suppressing biologics

If symptoms are severe or happening now, seek emergency care.

What the alpha-gal IgE blood test measures

The test measures the concentration of immunoglobulin E (IgE) antibodies in serum that are specifically directed against alpha-gal. It uses an ImmunoCAP-style allergen-specific IgE assay, the standard quantitative method for measuring allergen-specific IgE.

In the U.S., both Quest Diagnostics (test code 10554) and Labcorp (test code 650001) offer alpha-gal-specific IgE testing. Lab-specific methodology, specimen handling, reference ranges, and result reporting may differ. Current lab directory listings should be consulted for the most accurate operational details.

LabTestSuperstore offers the test through both Quest and Labcorp partner networks. Order online, receive a requisition, visit a partner draw site, and results are delivered through a patient portal in 3 to 7 business days. A licensed physician in the partner network reviews and authorizes every requisition.

What the results mean

Results are reported as a numerical alpha-gal sIgE concentration in kilounits of antibody per liter (kU/L).

Below 0.1 kU/L: Negative by the CDC and CSTE surveillance case definition. A value below this threshold indicates that no measurable alpha-gal IgE was detected. A negative result makes AGS unlikely as the cause of current symptoms, though it does not rule out other allergies or other causes.

0.1 kU/L and above: Positive by the CDC and CSTE surveillance case definition. Alpha-gal-specific IgE antibodies are present in measurable quantities. A positive result indicates that the immune system has been sensitized to alpha-gal, most commonly through tick exposure, and is consistent with AGS when symptoms fit.

A clinician interprets the result by comparing it with your symptoms, timing of reactions, tick exposure history, foods or products involved, medications, exercise or alcohol around the event, and whether similar reactions have happened before. Antibody concentration does not reliably predict reaction severity in any individual patient. Patients with low titers can still experience severe anaphylaxis, and patients with high titers may have mild reactions or none at all. Population-level data show that higher levels are associated with greater likelihood of clinical reactivity, but this does not translate to individual prediction.

A positive test alone does not confirm a clinical diagnosis. CDC explicitly states that positive alpha-gal sIgE tests may occur in people who do not have AGS, especially in lone star tick regions. Diagnosis is the combination of a positive blood test plus a clinical history that fits.

A negative test in someone with clear delayed reactions to red meat does not end the workup. IgE levels can decline over time during avoidance or in the absence of recent tick exposure, and rare cases of clinically significant AGS with very low alpha-gal IgE have been reported. If the symptom pattern strongly fits AGS but alpha-gal sIgE is negative or borderline, an allergist may consider repeat testing, total IgE context, testing for related food allergens, or supervised challenge decisions. Home food challenges after a severe reaction should not be attempted.

What clinicians typically recommend after a positive result

Clinical management of confirmed AGS is individualized and supervised by a primary care clinician or an allergist. Standard elements documented in the published literature and CDC patient-facing materials include:

Avoidance of mammalian meat (beef, pork, lamb, venison, rabbit, bison, goat) is commonly recommended for confirmed AGS. Dairy, gelatin, medications, and other products are handled more individually because tolerance varies.
Formal diagnosis and a management plan are typically established through a clinician, often including a prescription for an epinephrine auto-injector for emergency use.
Label reading and ingredient awareness.Alpha-gal is not labeled the way major food allergens are, except when cow's milk is involved (cow's milk is the only alpha-gal-containing ingredient classified as a major allergen under federal labeling rules). Mammalian gelatin, lard, tallow, broth, glycerin, magnesium stearate, and other mammalian-derived ingredients may not be obvious from the label.
Tick-bite prevention matters more for AGS patients than for the general population, because repeated bites can boost IgE levels and worsen reactions. Permethrin- treated clothing, DEET or picaridin on exposed skin, and tick checks after time outdoors are standard preventive measures.
Periodic IgE retesting can document declining antibody levels over time. With strict avoidance and no further tick bites, alpha-gal IgE levels often decline over months to years. Some patients eventually tolerate small amounts of mammalian products again, though this is determined under clinical supervision.
Medical alert documentation. People with confirmed AGS, especially those prescribed epinephrine or those with severe reactions, may benefit from adding AGS to their medical record allergy list and carrying medical alert information.

There is no established cure for AGS and no vaccine prevents it. Management focuses on avoiding triggers, preventing new tick bites, preparing for reactions, and reassessing tolerance over time with clinical supervision.

Alpha-gal in medications and medical products

Alpha-gal appears in pharmaceutical and medical products derived from mammalian sources. The list below covers exposures patients with confirmed AGS should ask their prescribing clinicians about:

Heparin from porcine intestinal source (the standard commercial source)
Gelatin-stabilized vaccines, including measles-mumps-rubella (MMR) and varicella vaccines
Cetuximab (Erbitux), the cancer drug whose hypersensitivity reactions led to the original identification of anti-alpha-gal IgE
Porcine heart valve replacements and other bovine or porcine surgical materials
Certain monoclonal antibodies produced in mammalian cell lines (Sp2/0, NS0)
Bovine and porcine collagen used in surgical hemostats, dermal fillers, and wound care
Pancreatic enzyme replacement products derived from porcine pancreas

This list is not exhaustive. Patients with confirmed AGS should disclose the diagnosis to every prescribing clinician and pharmacist and ask about alpha-gal content before procedures, surgeries, or new prescriptions.

Do not stop, delay, or refuse prescribed medication, vaccination, emergency treatment, anticoagulation, cancer therapy, or surgery based only on this list. The list is a prompt for discussion with the prescribing clinician, pharmacist, anesthesiology team, or allergist. Risk varies by product, route, dose, urgency, and the patient's reaction history. Not all AGS patients react to every alpha-gal-containing product.

Cross-reactivity in foods

Alpha-gal appears in more food sources than most patients expect:

Mammalian meat: beef, pork, lamb, venison, bison, rabbit, goat. Poultry (chicken, turkey) and fish do not contain alpha-gal and are generally tolerated by AGS patients.
Mammalian dairy: cow's milk, butter, cheese, yogurt, ice cream, whey. Tolerance varies between patients.
Gelatin: capsule shells, gummy vitamins, marshmallows, Jell-O, some candies, certain ice creams, some yogurts.
Broths and stocks: beef broth and some chicken broths contain meat-based fats. Labels should be checked.
Personal care products: lanolin (sheep-derived), some collagen products, some cosmetic ingredients.

When to seek emergency care

Anaphylaxis is a medical emergency. Standard emergency medical guidelines call for immediate use of a prescribed epinephrine auto-injector when systemic allergic symptoms appear, followed by emergency transport (calling 911 in the U.S.).

Symptoms that warrant emergency evaluation include:

Throat tightness or difficulty swallowing
Trouble breathing or wheezing
Drop in blood pressure causing dizziness or fainting
Rapid pulse with confusion
Widespread hives with any of the above
Severe abdominal pain, repeated vomiting, or severe diarrhea after possible alpha-gal exposure. Severe GI-only reactions can still be part of anaphylaxis and have been associated with delayed AGS fatalities.

The delayed onset of AGS reactions does not mean they are mild. Fatal anaphylaxis from alpha-gal-mediated reactions has been documented in the literature. Severity is not predictable from prior reactions.

Why AGS is underdiagnosed

The CDC's 2023 survey of U.S. healthcare providers, published as MMWR 72(30):809-814, found:

42% of surveyed providers had never heard of alpha-gal syndrome
Among those who had heard of it, fewer than one-third knew how to diagnose it
Two-thirds of providers said they wanted clinical guidelines for AGS diagnosis and management

Clinician awareness is one major barrier to diagnosis. Other barriers include delayed symptoms, GI-only presentations, regional variation in tick exposure, positive tests in people without symptoms, and the absence of national AGS surveillance reporting.

Privacy and reporting

AGS is not currently nationally notifiable to CDC, but some states may require reporting. If privacy or reporting practices matter to you, ask the testing service or clinician how positive results are handled in your state.

When standalone lab testing may fit

A serum alpha-gal IgE test may be useful if you have had delayed allergic-type symptoms after mammalian meat, dairy, gelatin, or other mammalian-derived products and want lab data to discuss with a clinician.

Testing is most useful when there is a symptom pattern to interpret. A positive result in someone without compatible symptoms may show sensitization, not clinical AGS.

Order the alpha-gal IgE test

Alpha-Gal IgE Test (Quest)
Quest test code 10554 · Single biomarker · Results in 3 to 7 business days

Alpha-Gal IgE Test (Labcorp)
Labcorp test code 650001 · Single biomarker · Results in 3 to 7 business days

Both tests measure alpha-gal-specific IgE in serum. The expanded alpha-gal panel that includes separate IgE tests for beef, pork, and lamb is also available, but published guidance treats the single alpha-gal IgE test as the test of record for initial evaluation.

A licensed physician in the LabTestSuperstore partner network reviews and authorizes every requisition. Results are delivered through your patient portal.

Frequently asked questions

How accurate is the alpha-gal IgE blood test?

The test is sensitive for detecting alpha-gal-specific IgE antibodies and uses the standard quantitative method for allergen-specific IgE testing. A negative test makes AGS unlikely; a positive test combined with a clinical history that fits is consistent with the diagnosis. Clinical correlation by a clinician is needed for a formal diagnosis.

How long after a tick bite does it take to develop AGS?

The timeline varies. Some people develop symptoms within weeks of a tick bite, others not for months. Sensitization can occur after a single bite or build up over multiple bites. No established minimum exposure threshold exists.

Can the allergy go away over time?

For some patients, yes. With strict avoidance of mammalian products and no further tick bites, alpha-gal IgE levels often decline over months to years, and some patients eventually tolerate small amounts of mammalian products under clinical supervision. New tick bites can re-sensitize and reset the clock. No current treatment accelerates resolution.

Can someone have AGS after eating red meat their whole life?

Yes. That is the typical pattern. AGS usually develops in adulthood in people who have eaten mammalian meat without incident for decades. Sensitization happens at the tick bite, not through dietary exposure.

Is AGS the same as a regular meat allergy?

No. A typical meat allergy is an IgE-mediated reaction to a protein in the meat, usually develops in childhood, and causes immediate symptoms. AGS is a reaction to a carbohydrate epitope (alpha-gal), typically develops in adulthood after a tick bite, and causes delayed symptoms 2 to 6 hours after eating, sometimes up to 8 hours.

Do AGS patients need to avoid chicken, turkey, or fish?

No. Poultry and fish do not contain alpha-gal and are generally tolerated by AGS patients. Some patients have concurrent allergies, but the alpha-gal mechanism does not apply to non-mammalian protein sources.

Does insurance cover this test if ordered directly?

Direct-to-consumer ordered tests through LabTestSuperstore are cash-pay. We do not bill insurance. To use insurance, a physician order through your regular healthcare channel is needed, and your physician's office can use the same Quest and Labcorp test codes (10554 and 650001).

Sources

Centers for Disease Control and Prevention. About Alpha-gal Syndrome. https://www.cdc.gov/alpha-gal-syndrome/about/
Centers for Disease Control and Prevention. Clinical Diagnosis and Testing: Alpha-gal Syndrome. https://www.cdc.gov/alpha-gal-syndrome/hcp/diagnosis-testing/
Centers for Disease Control and Prevention. Symptoms of Alpha-gal Syndrome. https://www.cdc.gov/alpha-gal-syndrome/signs-symptoms/
Centers for Disease Control and Prevention. Managing Alpha-gal Syndrome. https://www.cdc.gov/alpha-gal-syndrome/managing/
Centers for Disease Control and Prevention. Products That May Contain Alpha-gal. https://www.cdc.gov/alpha-gal-syndrome/data-research/products-containing-alpha-gal/
Carpenter A, Drexler NA, McCormick DW, et al. Health Care Provider Knowledge Regarding Alpha-gal Syndrome – United States, March–May 2022. MMWR Morb Mortal Wkly Rep. 2023;72(30):809–814.
Thompson JM, Carpenter A, Kersh GJ, et al. Geographic Distribution of Suspected Alpha-gal Syndrome Cases – United States, January 2017–December 2022. MMWR Morb Mortal Wkly Rep. 2023;72(30):815–820.
Binder AM, Commins SP, Altrich ML, et al. Diagnostic testing for galactose-alpha-1,3-galactose, United States, 2010 to 2018. Ann Allergy Asthma Immunol. 2021;126(4):411–416.e1.
Binder AM, Cherry-Brown D, Biggerstaff BJ, et al. Clinical and laboratory features of patients diagnosed with alpha-gal syndrome – 2010–2019. Allergy. 2023;78(2):477–487.
Chung CH, Mirakhur B, Chan E, et al. Cetuximab-induced anaphylaxis and IgE specific for galactose-alpha-1,3-galactose. N Engl J Med. 2008;358(11):1109–1117.
Commins SP, Satinover SM, Hosen J, et al. Delayed anaphylaxis, angioedema, or urticaria after consumption of red meat in patients with IgE antibodies specific for galactose-alpha-1,3-galactose. J Allergy Clin Immunol. 2009;123(2):426–433.
Steinke JW, Platts-Mills TA, Commins SP. The alpha-gal story: lessons learned from connecting the dots. J Allergy Clin Immunol. 2015;135(3):589–596.
Platts-Mills TAE, Gangwar RS, Workman L, Wilson JM. The Immunology of Alpha-Gal Syndrome. Immunological Reviews. 2025;332(1):e70035.
Iglesia EGA, Kwan M, Virkud YV, Iweala OI. Management of Food Allergies and Food-Related Anaphylaxis. JAMA. 2024;331(6):510–521.
McGill SK, Hashash JG, Platts-Mills TA. AGA Clinical Practice Update on Alpha-Gal Syndrome. Clin Gastroenterol Hepatol. 2023;21(4):891–896.
Wilson JM, Schuyler AJ, Workman L, et al. Investigation into the alpha-gal syndrome: characteristics of 261 children and adults. J Allergy Clin Immunol Pract. 2019;7(7):2348–2358.e4.
Saunders EF, Sohail H, Myles DJ, et al. Alpha-Gal Syndrome After Ixodes scapularis Tick Bite, Maine, USA, 2014–2023. Emerg Infect Dis. 2025;31(4):809–813.
Butler WK, Oltean HN, Dykstra EA, et al. Onset of Alpha-Gal Syndrome After Tick Bite, Washington, USA. Emerg Infect Dis. 2025;31(4):829–832.
Kersh GJ, Salzer J, Jones ES, et al. Tick Bite as a Risk Factor for Alpha-Gal-Specific IgE Antibodies. Ann Allergy Asthma Immunol. 2023;130(4):472–478.
Labcorp. Galactose-Alpha-1,3-Galactose (Alpha-Gal), IgE, Serum (Test 650001). https://www.labcorp.com/tests/650001
Quest Diagnostics. Galactose-Alpha-1,3-Galactose (Alpha-Gal) IgE (Test 10554). https://testdirectory.questdiagnostics.com/test/test-detail/10554

Editorial transparency

This page was produced using the mediAIx™ Enhanced multi-AI editorial pipeline. Five independent AI systems reviewed the content for medical accuracy, voice, reasoning, edge cases, and citation against current peer-reviewed literature. A board-certified physician on the LabTestSuperstore medical advisory team will review the final draft before this badge is updated to reflect physician sign-off. For details on each step, see How LabTestSuperstore content is reviewed.

This page is for educational use. It is not a substitute for individualized medical advice. Individuals experiencing symptoms consistent with AGS should consult a clinician. Anaphylaxis is a medical emergency; emergency services should be contacted immediately.

Alpha-Gal Syndrome: The Tick-Bite Allergy to Red Meat