Takeaway
This delayed allergy to red meat is making headlines and affecting people across the country. Alpha-gal can alter eating habits and cause life-threatening reactions that are sometimes difficult to pin down.
Lifelong learning in clinical excellence | August 6, 2026 | 3 min read
By Andrew Moore, MD, Johns Hopkins Medicine
A patient scenario
Imagine the scenario of a patient, John, a 55-year-old consultant whose hobbies include golfing and gardening. On several occasions he recalled waking in the middle of the night diffusely itchy, and with sudden onset abdominal pain and diarrhea. He’d almost passed out in the bathroom. Each of these episodes occurred after a barbecue dinner at his golf retreat. Initially thought to be food poisoning, subsequent workup showed that his alpha-gal IgE is strongly positive, consistent with an allergy to alpha-gal. He’d been bitten by ticks on multiple occasions in the past. How should John be counseled?
What’s alpha-gal?
Although present in many locations around the world, and caused by a variety of different ticks, an allergy to alpha-gal, or the carbohydrate galactose-α-1,3-galactose, most commonly occurs after a lone star tick bite in North America. Alpha-gal is present in all non-human, non-primate mammals. Lone star ticks are located across the eastern, southeastern, and south-central United States, although their habitat is expanding due to climate change—they can cause other diseases such as ehrlichiosis, but don’t transmit Lyme disease. Individuals can become sensitized to alpha-gal after a tick bite (and demonstrate a positive alpha-gal IgE), but not everyone becomes allergic to red meat—the reasons why some people become allergic aren’t entirely clear. However, the prevalence of alpha-gal is increasing dramatically in the U.S. and up to 25% people are now alpha-gal positive in tick-heavy states such as Arkansas.
Symptoms of alpha-gal syndrome may include hives, swelling, itching, nausea, difficulty breathing, passing out, and predominantly, abdominal pain and diarrhea. Symptoms usually occur from two to six hours after ingestion of red meat. This includes all beef, lamb, venison, and pork products, and for very allergic individuals may also include milk, dairy, and gelatin, an ingredient in many different medications and some vaccines. For example, Cetuximab is a cancer medication that contains alpha gal, as does heparin (depending on its source and purity). Intravenously administered medications may lead to a more acute allergic reaction than by oral ingestion. Bioprosthetic medical devices such as porcine valves can also be problematic.
Afflicted patients must avoid all red meat in their diet and review their medications to prevent future symptoms. Having injectable or intranasal epinephrine on hand to treat anaphylaxis is recommended for many patients, as the syndrome is potentially fatal. Over time, some people may lose their sensitivities, but being bitten by another lone star tick may lead to resensitization and worsening of the allergy.
What to advise this patient
For John, investigations demonstrated the presence of high titers of IgE to alpha-gal, in addition to both beef and pork. He should be counseled to avoid all mammalian meat, but may continue to eat chicken and fish. He should be cautious with all milk and dairy products and avoid them if symptomatic. He’s a candidate for intranasal or injectable epinephrine in case of subsequent reactions and should avoid re-exposure to ticks in the future.
The key points:
1. Alpha-gal prevalence is increasing rapidly in the U.S.
2. Prevention of tick bites prevents both alpha-gal syndrome de novo and increasing sensitization in those affected. Advise patients to wear long sleeve shirts and pants when outdoors, apply insect repellant, and remove ticks carefully without crushing them.
3. Diagnosis is based on clinical findings and serological tests, including IgE titers to alpha-gal, beef, pork and lamb. Skin testing has been found to have little utility in diagnosing alpha-gal.
4. Patients diagnosed with alpha-gal syndrome should continue to avoid ingestion of all red meat, and potentially, milk, dairy, and gelatin-containing products.
5. Referral to an allergist is warranted for management and treatment decisions.
Click here to learn more about alpha-gal.
This piece expresses the views solely of the author. It does not necessarily represent the views of any organization, including Johns Hopkins Medicine.