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Alpha-gal syndrome: A strange allergy caused by a tiny tick

A smiling man eats a salad in a restaurant.

May 18, 2026— Tick season has arrived, and it's off to a big start. The Centers for Disease Control and Prevention (CDC) reports that, in several parts of the U.S., emergency room visits for tick bites are higher than they've been since 2017.

Tick bites can transmit diseases such as Lyme disease and Rocky Mountain spotted fever. They can also cause a long-term condition that might surprise you: a food allergy called alpha-gal syndrome (AGS).

AGS is on the rise. The CDC estimates about 450,000 people in the U.S. have it. AGS can be long-lasting, serious and even life-threatening. Here's what you need to know.

Not just another food allergy

AGS develops when the saliva from a tick introduces a carbohydrate called alpha-gal into your body. Alpha-gal can trigger an immune system response. Weeks or months after the tick bite, that immune response can begin to cause an allergic reaction to foods and products that contain alpha-gal. Those products include:

  • Meat from any mammal, such as beef, pork, lamb, venison and rabbit, as well as mammal organ meat.
  • Foods cooked in mammal fat such as lard or tallow.
  • Broth, stock and gravy.
  • Milk and milk products.
  • Gelatin-containing or gelatin-coated products such as medications.

Less commonly, people may become sensitive to vaccines containing alpha-gal additives or stabilizers, as well as heart valves, antibodies or antivenoms from pigs or cows.

What to look for

Unlike many food allergies, AGS symptoms don't start right away. Symptoms usually don't appear until two to six hours after eating or being exposed to products containing alpha-gal, says the CDC.

AGS symptoms can range from mild to severe. They include:

  • A rash or hives.
  • Severe stomach pain.
  • Nausea or vomiting.
  • Diarrhea.
  • Indigestion or heartburn.
  • Decreased blood pressure.
  • Dizziness or feeling faint.
  • Difficulty breathing, shortness of breath or coughing.
  • Swelling of the throat, tongue, lips or eyelids.
  • Anaphylaxis (a life-threatening combination of allergic reactions).

Suspect AGS?

Let your doctor know. They can help determine the cause of your symptoms and give you advice on how to avoid serious reactions.

There's no cure for AGS. People with the condition should avoid eating the meat—especially fatty cuts—and organs of any mammal.

It's also important to steer clear of foods or medical products that contain gelatin. It can be difficult to know what those products are, so read the label.

Some people with AGS also need to stay away from dairy products.

Sources

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