Alpha-gal syndrome is an allergy that causes reactions after eating meat from mammals and products derived from mammals. Symptoms usually begin 2 to 6 hours after eating mammalian foods and include nausea and vomiting, abdominal pain, loose stools, rash and hives, and facial swelling.
The alpha-gal syndrome allergy is due to tick bites that create an immune response and cause an allergic reaction. In the U.S., the tick most often thought to cause meat allergy is the lone star tick. Multiple tick bites will cause a sensitization to the carbohydrate alpha-gal which sets off the immune response and the allergy. The lone star tick bite is usually quite small and may not be seen. Alpha-gal syndrome is not related to Lyme disease which is also caused by tick bites.
Alpha-gal syndrome can be diagnosed with a blood test that detects immunoglobulin E (IgE) antibodies to alpha-gal. The carbohydrate galactose-alpha-1,3 galactose (known as alpha-gal) is abundant in mammalian meats, especially beef, pork, and lamb. People with alpha-gal syndrome may also react to products derived from mammalian meat such as gelatin in foods and candies and some pancreatic enzyme replacement medications. Some patients with alpha-gal syndrome can also develop symptoms from eating dairy products. Reactions to the surgical placement of bovine or porcine heart valves have been reported in patients with alpha-gal syndrome.
Treatment involves avoidance of mammalian meat and derived products from mammalian meat. Patients can eat turkey, chicken and fish. There is evidence that the IgE antibodies to alpha-gal decrease in some patients over time and therefore symptoms can decrease or resolve. Additional tick bites however can increase the IgE antibody levels.