Alpha-Gal Syndrome
Allergy Symptoms, Diagnosis and Treatment

The recently identified alpha-Gal syndrome (AGS)—aka red meat allergy, tick-bite meat allergy, alpha-Gal allergy—is a type of serious, potentially life-threatening allergic reaction to red meat and other products made from mammals.1,2 Most patients that become allergic to alpha-Gal have tolerated red meat for years before being sensitized by a tick bite.3 Thus, the condition typically begins when a tick bites someone and transmits alpha-Gal, a sugar molecule found in most mammals.2 This may trigger an immune response, which on subsequent exposure can cause mild to severe reactions after consumption of red meat, organ meats, and other products made from mammals.2,4

Prevalence of alpha-Gal syndrome is increasing, and several tick species have been implicated.3 One study noted that out of 143 healthy blood donors from the tick-prevalent Stockholm area, 10 percent had immunoglobulin E (IgE) (i.e., an antibody associated with an immune-system response) to alpha-Gal.5,6 A report from Denmark and Spain showed similar results.6

Where is alpha-Gal found?

Alpha-Gal reactions are typically caused by ingestion of red meat (e.g., beef, pork, lamb, rabbit, horse, goat, venison, bear); organ meats (e.g., intestines, hearts, livers, kidneys), and other products made from mammals.2,4 Additional foods that may pose a risk for those with alpha-Gal syndrome include soup-stock cubes, gravy packages, flavor ingredients in prepackaged products, meat extracts used in flavoring, dairy products (e.g., milk, cheese, yogurt, butter), canned tuna (which can be contaminated by dolphin or whale), chicken or fish cooked on a grill contaminated with red meat, pork-gut casings for sausages, pork fat (used for cooking and often found in pastries and venison burgers), and suet.4,8 Meanwhile, fish, reptiles, and birds typically don’t contain alpha-Gal.1

Gelatin, which is normally derived from the collagen in the skin or hooves of large mammals, may also be problematic. In fact, most patients allergic to red meat are sensitized to gelatin, which is the main ingredient in items such as jelly babies (aka gummies), marshmallows, and jello.4,10 While rare, case reports show reactions to topical or oral gelatin can occur from items such as shampoo, collagen implants, catgut sutures, and collagen-derived contact lenses. Additionally, gelatin may pose a risk as a binding agent in tablets, capsules, suppositories, and confectionaries.10 Those with antibodies related to alpha-Gal syndrome also can have reactions to the cancer treatment cetuximab.2

Nonfood sources that may cause a reaction include some forms of monoclonal antibodies, vaccines, gelatin used as a plasma expander, enzyme replacements, bovine or porcine heart valves, antivenom, heparin (i.e., a glycosaminoglycan derived from pig intestines), and stearic acid and/or magnesium stearate (e.g., various tablets including acetaminophen, oxycodone, lisinopril, oxycontin).4

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Do I need to avoid all forms of alpha-Gal?

Cooking meat at high temperatures fails to destroy the allergenicity of several red meat proteins, and even a small amount of red meat can cause a severe reaction.7,8

How do I manage my allergy?

Your healthcare provider may recommend a plan that includes the following.1,2,4,8,11,12

  • Avoid consumption of red meat and organs. In roughly 80 percent of cases, doing so is sufficient treatment. However, up to 20 percent of individuals also need to avoid dairy and gelatin. Less than 1 percent of people must maintain awareness of the large number of products that are derived from mammals.
  • Check ingredient labels to ensure store-bought foods don’t contain red meat or meat-based ingredients, such as organ meats, gelatins, beef, pork, and lamb.
  • Ask your allergist for a list of foods to avoid.
  • Employ extra caution when eating in restaurants and at social gatherings.
  • Avoid tick-prone environments, such as wooded, bushy areas with long grass.
  • Treat clothing and gear with permethrin or buy pretreated clothing items.
  • Apply insect repellent with a minimum of 20-percent concentration of DEET to your skin. Such repellents can be toxic, so follow directions carefully.
  • Cover up in tick-prone areas by wearing shoes, long pants tucked into your socks, a long-sleeved shirt, a hat, and gloves.
  • Clear brush and leaves from your yard/garden and keep woodpiles in sunny areas (as opposed to shaded environments) to keep ticks at bay.
  • Check your pets, clothing, and children for ticks upon entering your home following an outing in tick-prone areas.
  • Shower as soon as you come indoors to help remove unattached ticks.
  • Remove any attached ticks as soon as possible. Use tweezers to gently grasp the tick near its head and pull the tick away carefully and steadily without crushing it. Dispose of the tick and apply antiseptic.

Your healthcare provider may direct you to take one of the following medications to improve your allergy symptoms:

  • Antihistamines for ongoing pruritus (aka itching).
  • Oral corticosteroids to limit swelling with angioedema (i.e., swelling under the skin).

If someone you’re with is having an allergic reaction and showing signs of shock, act quickly. Look for a weak, rapid pulse; trouble breathing; cool, clammy, and pale skin; confusion; and loss of consciousness. Immediately do the following:

  • Call local emergency services.
  • Ensure the affected individual is lying down with legs elevated.
  • Administer epinephrine immediately for any obvious signs of anaphylaxis.
  • Check the affected individual's pulse and breathing and administer CPR or other first-aid measures if necessary.

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Alpha-Gal Syndrome Allergen Facts, Symptoms, and Treatment

Common Symptoms

After eating red meat, people don’t experience symptoms of alpha-Gal syndrome for at least two hours, and many reactions appear three to five hours or more after consumption. However, many patients don’t have any symptoms, and if symptoms present, they may not occur with every exposure to red meat.7 Over time, symptoms may lessen or even disappear if sensitized individuals don’t receive additional bites from ticks carrying alpha-Gal.8

Symptoms of alpha-Gal syndrome can include:2

  • Swelling of various body parts, such as the lips, face, throat, and tongue
  • Hives and itchy, scaly skin
  • Wheezing or shortness of breath
  • Runny nose, sneezing
  • Stomach pain, diarrhea, vomiting, nausea
  • Headaches

Alpha-Gal syndrome may also cause anaphylaxis, which can include symptoms such as:2,9

  • Constriction of airways and swelling of the tongue or throat, causing wheezing or breathing difficulty
  • Dizziness, fainting
  • Nausea, vomiting, diarrhea
  • Skin reactions including itching, hives, and flushed or pale skin
  • Low blood pressure
  • Weak and rapid pulse

How do I know if I'm allergic?*

Skin-prick tests with extracts of pork or beef have been unreliable in diagnosing alpha-Gal syndrome. While intradermal skin tests for several food allergens may be useful, few clinics perform such testing. Thus, most allergists rely on a blood test for IgE to identify alpha-Gal.4

Together with your symptom history, specific IgE blood testing can help determine if you are sensitized to a particular allergen. If you are diagnosed with an allergy, your healthcare provider will work with you to create a management plan.

*These products may not be approved for clinical use in your country. Please work with your healthcare provider to understand availability.

Is there a risk for a severe event?

The clinical spectrum of symptoms for alpha-Gal syndrome includes anaphylaxis in up to 60 percent of individuals.11 If you experience a severe allergic reaction, you may need an emergency injection of epinephrine and a visit to the emergency room. Once you’ve been diagnosed with alpha-Gal syndrome, your healthcare provider or allergist likely will prescribe an epinephrine autoinjector.8

  1. Alpha-gal Allergy [Internet]. Centers for Disease Control and Prevention. Centers for Disease Control and Prevention; 2019; 2020 Oct 6. Available from: https://www.cdc.gov/ticks/alpha-gal/index.html.
  2. Mayo Clinic [Internet]. Rochester, MN: Mayo Foundation for Medical Education and Research; 2020 Nov 19. Available from: https://www.mayoclinic.org/diseases-conditions/alpha-gal-syndrome/symptoms-causes/syc-20428608.
  3. De la Fuente J, Pacheco I, Villar M, Cabezas-Cruz A. The alpha-Gal syndrome: new insights into the tick-host conflict and cooperation. Parasite Vectors. 2019 Apr 3;12(1):154. doi: 10.1186/s13071-019-3413-z. PMID: 30944017; PMCID: PMC6448316.Available from: https://parasitesandvectors.biomedcentral.com/track/pdf/10.1186/s13071-019-3413-z.pdf.
  4. Platts-Mills TAE, Li RC, Keshavarz B, Smith AR, Wilson JM. Diagnosis and Management of Patients with the α-Gal Syndrome. J Allergy Clin Immunol Pract. 2020 Jan;8(1):15-23.e1. doi: 10.1016/j.jaip.2019.09.017. Epub 2019 Sep 28. PMID: 31568928; PMCID: PMC6980324. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6980324/pdf/nihms-1060828.pdf.
  5. American Academy of Allergy Asthma & Immunology [Internet]. Milwaukee, WI: American Academy of Allergy Asthma & Immunology; 2021. Available from: https://www.aaaai.org/Tools-for-the-Public/Allergy,-Asthma-Immunology-Glossary/Immunoglobulin-E-(IgE)-Defined#:~:text=Share%20this%20page%3A,chemicals%2C%20causing%20an%20allergic%20reaction.
  6. Apostolovic D, Tran TA, Starkhammar M, Sánchez-Vidaurre S, Hamsten C, Van Hage M. The red meat allergy syndrome in Sweden. Allergo J Int. 2016;25(2):49-54. doi: 10.1007/s40629-016-0098-0. Epub 2016 Mar 23. PMID: 27656352; PMCID: PMC5016537. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5016537/pdf/40629_2016_Article_98.pdf.
  7. Steinke JW, Platts-Mills TA, Commins SP. The alpha-gal story: lessons learned from connecting the dots. J Allergy Clin Immunol. 2015;135(3):589‐597. doi:10.1016/j.jaci.2014.12.1947. Available from: https://www.jacionline.org/action/showPdf?pii=S0091-6749%2815%2900076-7.
  8. Mayo Clinic 2 [Internet]. Rochester, MN: Mayo Foundation for Medical Education and Research; 2020 Nov 19. Available from: https://www.mayoclinic.org/diseases-conditions/alpha-gal-syndrome/diagnosis-treatment/drc-20428705.
  9. Mayo Clinic Anaphylaxis 2 [Internet]. Rochester, MN: Mayo Foundation for Medical Education and Research; 2019 Sep 14. Available from: https://www.mayoclinic.org/diseases-conditions/anaphylaxis/symptoms-causes/syc-20351468.
  10. Mullins RJ, James H, Platts-Mills TA, Commins S. The relationship between red meat allergy and sensitization to gelatin and galactose-alpha-1,3-galactose. J Allergy Clin Immunol. 2012 May;129(5):1334-42. Available from. https://www.jacionline.org/action/showPdf?pii=S0091-6749%2812%2900368-5.
  11. Van Nunen S. Galactose-alpha-1, 3-galactose, mammalian meat and anaphylaxis: a world- wide phenomenon? Curr Treat Options Allergy. 2014;1(3):262-77. Available from: https://link.springer.com/content/pdf/10.1007/s40521-014-0022-0.pdf.
  12. Mayo Clinic [Internet] (Mayo Anaphylaxis). Rochester, MN: Mayo Foundation for Medical Education and Research; 2019 Sep 14. Available from: https://www.mayoclinic.org/diseases-conditions/anaphylaxis/diagnosis-treatment/drc-20351474.
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