Alpha-gal Syndrome
Also called: AGS, red meat allergy
Pathogen
IgE immune response to the alpha-gal sugar
Carried by
Lone star tick (Amblyomma americanum)
Alpha-gal Syndrome is not an infection but an allergy triggered by a tick bite — most often from the lone star tick. The bite can sensitize the immune system to a sugar called alpha-gal found in mammalian ('red') meat, so that eating beef, pork, lamb, or mammal-derived products later causes an allergic reaction. Uniquely, the reaction is delayed by 2–6 hours, which makes it easy to miss.
Symptoms
- Delayed (2–6 hour) reactions after eating red meat or mammal products
- Hives, itching, swelling
- Stomach pain, nausea, diarrhea
- Anaphylaxis in severe cases
Testing
A blood test for alpha-gal-specific IgE antibodies, interpreted alongside your history. A positive IgE alone isn't diagnostic — it's common in areas with lone star ticks — so the clinical story matters.
Labs often used in the Lyme community:
See our Testing Guide to understand your options.
Geography
Closely tracks the range of the lone star tick — the South, East, and Central US — with cases expanding as the tick spreads. Estimates suggest hundreds of thousands of Americans may be affected.
Explore the Where Ticks Live map to see what's carried in your region.
Treatment overview
There's no cure; management means avoiding mammalian meat and mammal-derived products, and carrying emergency epinephrine if you're at risk of anaphylaxis. Some people's sensitivity fades over time if they avoid further tick bites.
Frequently asked questions
Can a tick bite really make me allergic to meat?
Yes. A lone star tick bite can sensitize your immune system to the alpha-gal sugar in mammalian meat, causing delayed allergic reactions to beef, pork, lamb, and mammal-derived products.