What Is Alpha-Gal Syndrome?

The condition entails becoming allergic to red meat after a tick bite.

Alpha-gal syndrome (AGS) is a serious allergic reaction to red meat, usually caused by lone star tick bites. Alpha-gal is short for galactose-alpha-1,3-galactose. It's a carbohydrate found in the blood and meat of mammals such as beef, lamb, pork, and venison.

Symptoms mimic those of food or other allergies. AGS can happen to anyone; however, people living in certain parts of the United States may be more susceptible to developing AGS. The condition can be permanent, but symptoms can be treated and managed with preventative and avoidance measures.


Most people with AGS experience an allergic reaction anywhere between two to six hours after eating red meat. Symptoms vary but can include:

  • Cough
  • Dizziness or fainting
  • Eyelid, lip, throat, or tongue swelling
  • Heartburn or indigestion
  • Itchy skin or hives
  • Severe stomach pain
  • Vomiting and diarrhea

Some people can experience a full-blown anaphylactic reaction, which can include a dangerous drop in blood pressure and difficulty breathing.

What Causes Alpha-Gal Syndrome?

When ticks feed off animals like deer and then bite a human, they can expose that human to alpha-gal molecules. The exposure to meat triggers their immune system to produce antibodies to fight alpha-gal.

Those antibodies build over the following weeks and months, eventually resulting in allergic reactions every time that person eats red meat. Some people also react to dairy products, medications, or foods containing gelatin.

The lone star tick has been the main tick found to be responsible for AGS. That does not mean that lone star ticks are the only ones that can lead to developing AGS—other ticks have not been excluded as potential culprits.

Also, not all people who are bitten by ticks will develop AGS. Research is ongoing to determine why only certain individuals are susceptible to the condition.

Risk Factors

You are more likely to develop AGS if you spend a lot of time in wooded areas with ticks, as the condition primarily occurs with tick bites. Also, multiple tick bites can make a person more likely to experience allergic reactions to alpha-gal.

AGS can affect people of all ages, though AGS cases occur more often in adults. Many reported cases come from residents in the South, the East, and Central US, but increased reported cases have come from the North and West US too.

How Is It Diagnosed?

An allergist will get information about your personal and medical history along with a physical exam. They may recommend the following if clinical history warrants it:

  • Blood testing: A blood test will measure immunoglobin E (IgE) antibody levels specific to alpha-gal.
  • Skin testing: An allergist may complete a skin test for determining skin reactions to products containing alpha-gal.

Note: Testing will not confirm an AGS diagnosis, and it's possible to have a false negative.


The main purpose of treatment is to relieve and reduce any allergic reactions. Primary treatment includes medications and avoidance of red meat and alpha-gal-containing products.


Since AGS is a food allergy, medications may be used to treat allergy symptoms like hives or shortness of breath. They may include antihistamines or epinephrine.

Red Meat and Alpha-Gal Avoidance

Another part of the treatment entails avoidance of red meat sources like beef, lamb, or pork. Poultry and seafood do not lead to similar allergic reactions.

You may also need to avoid certain products with alpha-gal. Everyone with AGS will not react to all ingredients with alpha-gal. The entire list of foods or products a person needs to avoid will depend on how sensitive they are and how severe their reactions are.

How Can You Prevent Alpha-Gal Syndrome?

Preventing AGS may be possible by preventing tick bites. To do so:

  • Avoid areas where ticks live such as grassy, brushy, or wooded areas.
  • Conduct tick checks on you, family members, and pets who may have spent time outdoors with you.
  • Remove any ticks on your body as soon as possible.
  • Wear Environmental Protection Agency (EPA)-registered insect repellant with DEET.
  • Treat any clothing or gear you're using with 0.5% permethrin.

Also, pay attention for the next month or two for any symptoms. Consult a healthcare provider if you have any type of reaction following a possible tick bite.

Is Alpha-Gal Syndrome Permanent?

AGS can be permanent for many individuals. Because it is a food allergy, there is a possibility for a person to become less sensitive to red meat over time. Still, that lessened sensitivity, if it occurs, may not happen for a few years.

Living with the Condition

It's unclear how prevalent alpha-gal syndrome is nationwide, but case estimates are in the thousands. Also, treatment can involve life-long dietary changes and physical, psychosocial, emotional, and financial effects for individuals with AGS, their families, and their caregivers.

Researchers and healthcare providers are trying to learn more about the condition, how to identify it more effectively, and other treatments that may be helpful. For example, one study discussed oral immunotherapy (OIT), which involves taking allergens over time, as a way to reduce immune system reactions.

A Quick Review

AGS is a condition known as a red meat allergy, which usually occurs following a lone star tick bite. Allergic reactions due to AGS are delayed by hours but can include mild to severe symptoms, including anaphylaxis. Diagnosing AGS involves a clinical history, physical exam, and often blood testing and skin testing.

The condition may be permanent, though it's possible to become less sensitive to red meat over time. Still, treatment is typically allergy medications or life-long changes in your diet by avoiding red meat or certain products that may contain alpha-gal.

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6 Sources
Health.com uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Centers for Disease Control and Prevention. Ticks - alpha-gal syndrome.

  2. US Department of Health and Human Services. Alpha-gal syndrome subcommittee report to the tick-borne disease working group.

  3. Centers for Disease Control and Prevention. Alpha-gal syndrome for healthcare providers factsheet.

  4. American Academy of Allergy, Asthma, and Immunology. Alpha-gal and red meat allergy.

  5. Commins SP. Diagnosis & management of alpha-gal syndrome: lessons from 2,500 patientsExpert Review of Clinical Immunology. 2020;16(7):667-677. doi:10.1080/1744666X.2020.1782745

  6. Vaz-Rodrigues R, Mazuecos L, de la Fuente J. Current and future strategies for the diagnosis and treatment of the alpha-gal syndrome (AGS)JAA. 2022;Volume 15:957-970. doi:10.2147/JAA.S265660

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