What is alpha-Gal syndrome (AGS)?

Alpha-Gal Syndrome is just plain weird. And the more we learn about it, the stranger it seems to get. Also known as "red meat allergy," "mammalian meat allergy," or "tick-bite allergy," the syndrome is when an allergic reaction to alpha-Gal, which is a sugar molecule found in mammal meat such as beef, pork, venison, and more.^1-2 But this reaction actually begins with a bite from a lone star tick (or possibly a chigger).^2-3

No, really. It's not a made-up disease.

It works like this: The tick (or chigger) feasts on a mammal such as a deer, and in doing so, it ingests alpha-Gal. If it bites a human, it can transmit this molecule into the person’s bloodstream.^2-3 This can then trigger an allergic reaction if they eat any mammalian products. The reaction can range from mild to severe and even life-threatening symptoms.² However, eating other types of meats like poultry, fish, and shellfish won't cause alpha-Gal Syndrome symptoms.

Alpha-Gal Syndrome symptoms include:²

• Hives
• Sneezing
• Stomach pain
• Diarrhea
• Wheezing or shortness of breath
• Vomiting
• Nausea
• Anaphylaxis

Rather than happening soon after eating (as is the case with many food-related allergies), an alpha-Gal allergy symptoms typically don’t occur for three to six hours after eating red meat or other mammalian products.² Therefore, this delayed response may leave some asking, "What did I eat that caused my allergic reaction?"

Alpha-Gal Syndrome is also relatively unknown. In fact, it wasn’t reported until the late 2000s.⁴ Chances are that some people, including healthcare providers, still aren’t familiar with it. Thus, diagnosis can be tricky.⁵

The number of patients with this type of red meat allergy continue to rise, and scientific research on this novel but serious condition continues. So here are 10 newly discovered and/or surprising facts about this odd disease that will make you want to bust out the tick spray. And if you think you may suffer from AGS, be sure to speak to your health care provider about whether you should get tested.

(To learn even more about alpha-Gal Syndrome, including symptoms, exposure-reduction tactics, and a list of things that may contain alpha-Gal, check out our fact sheet.)

1. Across the globe, bites from several types of ticks (and potentially chiggers) can lead to AGS.^3,5,6

Initially, this syndrome was linked to the Lone Star Tick, which is found mostly in the southeastern United States.² However, alpha-Gal Syndrome has now been reported on all continents except Antarctica, and at least eight tick species are confirmed or suspected culprits associated with the condition.⁴

However, because some of these ticks prey on deer, they can be brought across state lines to new environments as herds migrate and travel. This means increasing deer populations and/or environmental factors that cause herd migrations (like climate change or land development), may be responsible for bringing alpha-Gal carrying ticks to foreign states. For example, the Lone Star Tick was previously rare in Michigan, but it’s now the third most common tick in the state.⁶ Plus, a 2022 article in the Toronto Star revealed that the Lone Star tick is expanding from the United States into Canada due to rising temperatures.⁷

Also note that many tick bites go unnoticed, particularly from “seed” ticks. Although these baby ticks are the size of a poppy seed, they can still transmit alpha-Gal.⁶ Recent reports also suggest that bites from chiggers, which are microscopic arachnids (like spiders), may also lead to AGS.^3,5,8

Alpha-Gal associated meat allergy described worldwide¹

2. Blood testing is paramount in testing for alpha-Gal; skin-prick tests (SPTs) aren't effective.⁹

Given the time and money that can be involved in securing a diagnosis, testing for alpha-Gal syndrome is critical. There is no explicit AGS treatment, so it’s vital to receive a proper diagnosis to know what products and foods to avoid.

How do you test for alpha-Gal syndrome? You need to get the right test straight out of the gate, and a skin-prick test (SPT) probably isn’t the way to go. In fact, SPTs with extracts of pork or beef have been unreliable in detecting alpha-Gal.⁹

Is there a test for alpha-Gal?

Yes. You can ask your healthcare provider for an alpha-Gal allergy blood test. But instead of a whole allergen blood test, which helps providers rule allergies in or out, an allergen component test for alpha-Gal allergy may help to pinpoint the specific sugar molecule that is causing symptoms. Plus, allergen component testing may offer providers insight into the severity of an individual’s reactions.

However, it may not be enough just to ask for an allergy test. You need to be specific to ensure you get the right one: an alpha-Gal IgE test. To be even more specific, you want an alpha-Gal specific IgE component test. Additionally, your provider may want to test for beef, pork, lamb, and tryptase (a chemical involved in allergic reactions) to help develop a clear diagnosis.

3. A cancer-related drug trial led to the discovery of alpha-Gal Syndrome.⁶

Alpha-Gal Syndrome was discovered via drug trials for Cetuximab, which is an antibody treatment containing alpha-Gal aimed at colorectal cancer and cancer of the head and neck. A number of patients enrolled in the clinical trials developed anaphylaxis or hives after the first dose of Cetuximab. This mysterious reaction led to further investigation and later to identification of the syndrome in the mid 2000s.⁶

4. The list of alpha-Gal Syndrome symptoms may be getting longer, and some symptoms can mimic those of Irritable Bowel Syndrome (IBS).¹⁰

Symptoms of alpha-Gal syndrome can range from an itchy rash and hives to diarrhea and anaphylaxis.⁵ In fact, severe reactions like anaphylaxis occur in up to 60 percent of people with this red meat allergy.¹¹

According to survey results presented at the American Academy of Allergy, Asthma, and Immunology's (AAAAI) Annual Meeting, some alpha-Gal Syndrome patients have a wide range of seemingly new symptoms, such as those involving the cardiovascular, nervous, and motor systems. Furthermore, some patients reported a wide range of mental health issues, such as anxiety, depression, fatigue, poor memory, irritability, sleep disturbances, etc.¹²

Additionally, alpha-Gal allergy symptoms may closely resemble those of IBS. According to a 2021 study in the Journal of Gastroenterology, some people with alpha-Gal Syndrome only have gastrointestinal symptoms, such as abdominal pain, nausea, and diarrhea.

One way to know for sure is to test for alpha-Gal and ask your healthcare provider for a specific IgE blood test or more specifically, a component blood test.

5. Some people could develop symptoms from not only eating meat but also inhaling fumes from meat being cooked.⁵

Similar to some individuals with a shellfish allergy, people sensitized to alpha-Gal have also reported symptoms after inhaling fumes of mammalian meat being cooked.^5,13 That is, in addition to developing symptoms after eating meat, some people have symptoms after inhaling meat fumes.

6. Alpha-Gal can hide in some surprising foods, products, and medical items.

Alpha-Gal reactions are typically caused by eating mammalian meat and meat products derived from animals such as cows, pigs, lambs, rabbits, buffalos, bison, and kangaroos.⁶ However, since a myriad food items contain meat-based ingredients, they may also contain alpha-Gal. (Check out our alpha-Gal fact sheet for a fairly extensive list of potential alpha-Gal sources.)

Take gelatin, for example. It’s typically made of collagen from the skin and/or hooves of large mammals, so it may cause AGS symptoms.

Gelatin or collagen can be found in the following:^{9, 14 15}

• Gummies
• Marshmallows
• Jell-O
• Catgut sutures
• Collagen-derived contact lenses
• Shampoo
• Tattoo ink

Alpha-Gal may be found in various vaccines, antivenom, and medical tablets (e.g., acetaminophen, oxycodone, lisinopril, and oxycontin), and in cow and pig heart valves, which are sometimes transplanted into humans.⁹

What’s more, some ingredients made from red algae, such as carrageenan, also may contain a type of alpha-Gal. Carrageenan is sometimes used in beer, condiments, infant formulas, salad dressings, and much more.¹⁶ So avoiding alpha-Gal isn’t as easy as simply steering clear of burgers and hot dogs.

7. Alpha-Gal-free pigs are totally a thing.¹⁷

GalSafe pigs are, according to a recent article in Allergic Living, a new breed of pigs that have been genomically altered to eliminate alpha-Gal. This doesn’t simply mean that those suffering from the syndrome may be able to eat pork chops and bacon once again. It also means that since these pigs might be used for other purposes, those end products could be available to those with alpha-Gal Syndrome in the future.¹⁷

8. Exercise, alcohol, recent tick bites, and nonsteroidal anti-inflammatory drugs (NSAIDs) may increase risk and/or severity.^{9, 18}

For patients with alpha-Gal Syndrome, there are several co-factors that may further increase the risk for a reaction or the severity of symptoms upon exposure to alpha-Gal. These risk factors include atopy (i.e., a genetic tendency to develop allergic diseases), alcohol consumption, exercise, age, and use of certain medications, which includes nonsteroidal anti-inflammatory drugs (NSAIDS) like aspirin (e.g., Bayer), ibuprofen (e.g. Advil), naproxen (e.g., Aleve), and celecoxib (Celebrex).^{9, 18}

Similarly, while a single tick bite can kick off this syndrome, additional bites can increase a person’s sensitivity to alpha-Gal.⁵ Thankfully, according to information from the Mayo Clinic, symptoms may lessen or even disappear over time if sensitized individuals don’t receive additional bites from ticks carrying alpha-Gal.¹⁹

9. For the majority of patients in one study, it took seven years to obtain an alpha-Gal Syndrome diagnosis.²⁰

While info on alpha-Gal Syndrome is offered by many medical-information sources, such as the Centers for Disease Control and Prevention (CDC), the condition is still relatively unknown.^1,4,20 In fact, one study revealed that almost 80 percent of patients with alpha-Gal syndrome struggled to find a diagnosis for more than seven years.²⁰ (That’s 2,555 days of suffering.)

What’s even worse is that in trying to determine the cause of their symptoms, some patients underwent exploratory surgery, removal of their gallbladder or appendix, and partial removal of the pancreas before they finally received an alpha-Gal Syndrome diagnosis.⁵ And according to a 2017 paper, patients are more likely to discover alpha-Gal online, on the radio, or through personal connections than by visiting the emergency room due to anaphylaxis.²⁰

These stats are particularly troubling because an alpha-Gal IgE simple blood test (along with a medical history and physical exam) can help a healthcare provider diagnose this syndrome. In fact, a single visit with your healthcare provider and a blood draw could help save you not only a boatload of time and money otherwise spent on specialists and unnecessary tests but also a mountain of misery.

10. While it sounds totally made up, Pork-Cat Syndrome is real and sometimes confused with alpha-Gal Syndrome.²¹

Pork-Cat Syndrome is a rare allergic reaction to a protein that’s found in both cat dander and pork, and being sensitized to this protein in cats can cause a person to have allergic symptoms when they consume pork.²¹ This is actually a type of cross-reactivity, which is when the body's immune system identifies the proteins in one substance (e.g., pollen) and the proteins in another (e.g., a fruit or vegetable) as being similar.²² When the person contacts either one, the immune system may create allergy-like symptoms.

Symptoms of Pork-Cat Syndrome vary from hives to anaphylaxis, which means some symptoms overlap with alpha-Gal Syndrome.²¹ Plus, since both conditions may involve reactions to pork, misdiagnoses of these conditions are possible. If you think you have either of these pork-related problems, ask your healthcare provider for an allergen component blood test to home in on your pork peculiarities.

Do you have alpha-Gal Syndrome?

How to test for alpha-Gal? The best way to determine if you’ve developed alpha-Gal Syndrome is to talk to your healthcare provider and request a specific type of blood test: an alpha-Gal specific IgE component test. Almost any healthcare provider can order this test for you. But to prepare for your next appointment, check out “How to Ask Your Healthcare Provider for an Allergy Blood Test,” which offers seven key talking points and corresponding research-based facts to support an effective conversation with your provider.

Before your visit, complete our symptom tracker, which will generate a comprehensive symptom profile you can review with your healthcare provider to decide if a specific IgE blood test is right for you.

Finally, bone up on additional allergy info in our Living with Allergies section and via our Allergen Fact Sheets.

Finally, bone up on additional allergy info in our Living with Allergies section and via our Allergen Fact Sheets.