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Alpha-Gal: What You Need to Know About the Red Meat Allergy Caused by Ticks

New research from the CDC shows cases are rising in the U.S.

spinner image close up of the Lone Star tick on human skin
Bob Balestri / Getty Images

A red meat allergy brought on by a tick bite is now considered an emerging health concern, and experts warn that hundreds of thousands of Americans could be impacted.  

Research released July 27 by the Centers for Disease Control and Prevention (CDC) reports that far more people than previously thought have been affected by this serious allergy, known as alpha-gal syndrome. More than 110,000 suspected cases were identified between 2010 and 2022, but because alpha-gal is likely underdiagnosed, as many as 450,000 people may have been affected since 2010, the researchers report.

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“Alpha-gal syndrome is an important emerging public health problem, with potentially severe health impacts that can last a lifetime for some patients,” Ann Carpenter, an epidemiologist with the CDC, said in a news release. “It’s critical for clinicians to be aware of [alpha-gal syndrome] so they can properly evaluate, diagnose and manage their patients, and also educate them on tick-bite prevention to protect patients from developing this allergic condition.”

Alpha-gal’s rise coincides with a spike in other tick-borne diseases, which more than doubled between 2004 and 2016, federal data shows. The alpha-gal allergy can be triggered weeks after a bite from the lone star tick and possibly other varieties.

“We’re continuing to identify new patients every week in allergy clinics across the Southeast and East who’ve had essentially brand-new reactions,” says Scott Commins, M.D., an associate professor of medicine at the University of North Carolina and a leading expert on alpha-gal syndrome. “And that has been a big change over the past, say, 10 years.”

What is alpha-gal? 

Symptoms of alpha-gal syndrome

Reactions can range from mild to severe and may include:

  • Hives or itchy rash
  • Nausea or vomiting
  • Heartburn or indigestion
  • Diarrhea
  • Cough, shortness of breath or difficulty breathing
  • Drop in blood pressure
  • Swelling of the lips, throat, tongue or eyelids
  • Dizziness or faintness
  • Severe stomach pain

Source: Centers for Disease Control and Prevention

Alpha-gal is a sugar molecule — many mammals have it, including cows and pigs, and Commins says researchers have come to understand that some ticks do too. But it’s not found in people, so when a person gets a bite from a tick that has alpha-gal in its saliva, the body creates an immune response to the molecule, and some people have a strong allergic response.

“So then when we eat a hamburger, hotdog, etc., we have an allergic reaction to the meat, and it’s specifically to that alpha-gal that’s in pigs and cows,” Commins says. This is the case even if a person has been able to eat red meat their whole lives without a problem.  

Recognizing the symptoms of alpha-gal

Unlike with other food allergies, symptoms of alpha-gal syndrome don’t come on right away. “If you have a peanut allergy and you go out to a restaurant and you get an accidental exposure, you know you’re in trouble before you leave the restaurant,” says Jeffrey Wilson, M.D., an allergist and immunologist and an assistant professor of medicine at the University of Virginia.

With alpha-gal, however, it could be hours — three to six, or more — before hives or a rash develop, or you start to feel light-headed and short of breath. Other common warning signs include indigestion, nausea, vomiting, diarrhea and severe stomach pain.

This delay can make it difficult for people to see the connection between what they ate and their symptoms, Commins says. To complicate matters even more, some people experience only gastrointestinal (GI) symptoms, which are easy to blame on food poisoning or a stomach bug.

The American Gastroenterological Association recently updated its guidance for physicians to consider alpha-gal syndrome in patients with “unexplained GI symptoms of abdominal pain, diarrhea, nausea and vomiting” — especially if they live in an area where ticks and the allergy are prevalent (the Southeast, mid-Atlantic, Midwest and East Central regions). The group notes that a history of waking up at night with GI distress may also signal the syndrome.


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Another possible warning sign is redness or irritation in the spot where the tick latched on that is slow to heal. “Some folks would say it even felt like a knot under the skin,” Commins says.

If you notice these symptoms after eating mammalian meat (beef, pork, lamb, venison, etc.), talk to your primary care provider or an allergist. A blood test, alongside an exam and patient history, is often used to diagnose the allergy; your doctor may also order an allergy skin test.

One thing to note: If you’re getting a routine allergy test but don’t have symptoms of alpha-gal syndrome, know that some people produce antibodies for the molecule but don’t have a full-blown allergy. “So a positive test does not automatically mean you have a red meat allergy,” Wilson says.

There is no treatment for alpha-gal syndrome, though experts say it’s possible the allergy fades over time, especially if you’re able to dodge additional tick bites. Those with the allergy — which can range from minor to severe — have to avoid red meat and often other products containing alpha-gal, like meat broth or stock and gelatin made from beef or pork. Some people are unable to eat dairy.  

Ticks on the move

Pinning down a reason for the rise in alpha-gal syndrome is tricky, experts say. Food allergies, in general, are increasing, Wilson notes. There’s also more recognition and awareness of alpha-gal, though many health care providers still aren’t familiar with it, the latest CDC research shows.

And because tick-borne diseases are increasing overall, Commins says, “it kind of makes an argument that people are just coming in contact [with ticks] and being bitten more frequently.”

Interestingly, the tick population fluctuates on a yearly basis, says entomologist Michael Raupp. But one thing that has grown steadily is their reach. With warmer temperatures, ticks have been expanding farther north.

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“This is a phenomenon that’s going on with lots and lots of different kinds of insects and arthropods, including ticks,” says Raupp, professor emeritus at the University of Maryland. “And because the tick is now moving into these areas, you’re going to have cases of the red meat allergy and [other tick-borne diseases] in these areas where they haven’t been before.”

To avoid ticks and any allergies or ailments they transmit, Raupp has a few tips.

  • Stick to a paved surface or the center of the trail when walking or hiking. Ticks are most often lurking in the lush vegetation.
  • Tuck your pant legs into your socks if you’re going to be out in grasses and brush.
  • Too hot for pants? Reach for a spray repellent. The CDC recommends using an EPA-registered insect repellent containing DEET, picaridin, IR3535, oil of lemon eucalyptus (OLE), para-Menthane-diol (PMD) or 2-Undecanone.
  • You can also treat your clothing and boots — not your skin — with products containing 0.5 percent permethrin. The CDC has more information on how to do that. Or you can buy clothing that has already been treated.
  • Put your garments directly in the wash or even just the dryer when you get home. “And if you spin that on a medium to high cycle for about 30 minutes, you’ll kill any ticks that might have come home with you,” Raupp says. Also, take your shoes off outside so you don’t bring any ticks in the house, and examine pets and any gear outside as well, such as backpacks.

If you notice a tick on your body — and it’s important to check routinely — make sure you:

  • Remove it as soon as possible. It takes the tick about 36 to 48 hours to transmit diseases like Lyme, according to the CDC. “So if you can get that tick off in the first 24 hours, it’s going to greatly decrease your chances of contracting a tick-borne illness,” Raupp says.
  • When you do get the tick off, don’t flush it. Identifying the tick can help you understand your risks. “If it’s a black-legged tick, that puts Lyme disease in the picture,” Raupp says. The primary tick associated with a red meat allergy is the lone star tick. Many universities and health departments offer tick identification services, including the University of Maryland and the University of Rhode Island.

Editor's note: This story, originally published May 5, 2023, has been updated to reflect new information.

Video: Top 5 Tips for Preventing Tick-Borne Disease
Even more strategies to help protect yourself from disease-carrying tick bites.

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