Alpha-gal is a carbohydrate found in the meat of mammals, such as cows, pigs, and sheep. Some people develop an allergy to alpha-gal after being bitten by certain ticks, particularly the Lone Star tick. This allergy can cause reactions ranging from mild hives to severe anaphylaxis when consuming mammal-derived products. Symptoms of an alpha-gal allergy typically occur several hours after eating meat, making it different from many other food allergies. Individuals with this allergy may need to avoid not only red meat but also other products containing mammal-derived ingredients, including some dairy products and gelatin.