Alpha-gal syndrome (AGS) is a serious and potentially life-threatening allergic condition triggered by the bite of certain ticks, primarily the lone star tick in the United States. According to CDC estimates, as many as 450,000 people in the U.S. may be affected by AGS. When a tick bites a person, it can transfer a sugar molecule called alpha-gal Alpha-gal is a molecule (galactose-α-1,3-galactose), found in most mammals but not in humans, into the bloodstream, prompting the body to produce antibodies against it. This leads to an allergy where individuals experience reactions after consuming red meat (such as beef, pork, lamb, venison, or rabbit), dairy products, or other items containing alpha-gal, like certain medications or gelatin-coated products).
Symptoms of AGS typically begin 2–6 hours after exposure to triggers, which is a key distinguishing feature from most food allergies that occur more immediately. Common signs include hives, itchy rash, nausea, vomiting, severe stomach pain, heartburn, diarrhea, shortness of breath, drop in blood pressure, swelling of the lips/throat/tongue/eyelids, dizziness, or even anaphylaxis, a severe, potentially life-threatening reaction involving multiple symptoms. Reactions can vary in severity from mild to severe among individuals and even from one exposure to the next, and it may take weeks to months after a tick bite for symptoms to first appear.
The condition is underreported in large part because it is not nationally notifiable. As of 2025, the Florida Department of Health does not track cases. Cases are most common in southern, eastern, and central states where lone star ticks are prevalent, affecting people of all ages but predominantly adults, including those with higher outdoor exposure like hunters. Diagnosis involves a healthcare provider reviewing history, symptoms, and blood tests for alpha-gal antibodies, while management focuses on avoiding triggers under the guidance of an allergist, with the primary prevention strategy being tick bite avoidance.
For patients or medical care providers wanting to learn more about AGS, there are free online courses eligible for CME credits:
• Clinician Training and Resources | Alpha-gal Syndrome | CDC
