Tick bites can spread illnesses like Lyme disease or Rocky Mountain spotted fever. These illnesses are caused by parasites and bacteria that ticks carry. But did you know that a tick bite can also trigger a strange and serious food allergy?
This condition is called alpha-gal syndrome (AGS)—also known as red meat allergy. It’s a growing concern in many parts of the U.S., and it can cause allergic reactions that are delayed for several hours after eating red meat or other products made from mammals. Let's explore what AGS is, how it happens, who’s at risk and how you can find out if you have it.
What is alpha-gal syndrome (AGS)?
AGS is a serious and potentially life-threatening allergy that can develop after a bite from some kinds of ticks, especially the common lone star tick. It causes your immune system to react to a sugar molecule called alpha-gal, which is found in most mammals, but not in humans. This molecule is also present in the saliva of certain ticks, especially the lone star tick, which is common in the southern and eastern U.S.
When a tick carrying alpha-gal bites you, it can introduce the sugar molecule into your bloodstream. In some people, this triggers the immune system to produce antibodies against alpha-gal. Later, when those who develop the antibodies eat red meat (like beef, pork or lamb) or other mammalian products (like dairy or gelatin, which can be an ingredient in many food products and medicines), their body may react as if it’s under attack.
Common symptoms of AGS include:
- Hives or itchy skin
- Swelling of the face, lips, throat or eyelids
- Shortness of breath or wheezing
- Abdominal pain, nausea, vomiting or diarrhea
- Dizziness or fainting
- In severe cases, anaphylaxis, a life-threatening allergic reaction
Symptoms of AGS may be delayed and appear 3 to 8 hours after eating mammalian products, which makes AGS different from most food allergies that cause immediate reactions.
Who’s at risk for AGS?
While tick bites are the main cause of AGS, not everyone bitten by a tick will develop the condition. The allergic reaction in those with AGS can also vary, from severe and sometimes life-threatening, to mild or even no reaction, and it can also differ based on what food or product the person consumed. Scientists are still studying why some people react and others don’t.
Risk factors of AGS include:
- Spending time in wooded or grassy areas where ticks live
- Living in or visiting South, East or Central U.S. states, where lone star ticks are most common
- Having multiple tick bites
- Being an outdoor enthusiast, such as a hiker, camper or hunter
How to prevent tick bites:
- Wear long sleeves and pants when outdoors
- Use EPA-approved insect repellents
- Stay on clear trails and avoid tall grass
- Check yourself and pets for ticks after being outside
- Remove ticks with tweezers, pulling straight out without twisting, as soon as possible after discovering them
- Clean the bite area with antiseptic after removal
How do you know if you have AGS?
If you’ve recently had a tick bite or been exposed to tick-prone areas and later experienced unexplained allergic symptoms—especially after eating red meat or dairy—an alpha-gal test may help determine whether you have AGS. Labcorp OnDemand’s Alpha-Gal Allergy Test measures the level of IgE antibodies in your blood that react to alpha-gal. This helps determine whether you have developed an allergic sensitivity to alpha-gal and are at risk for allergic reactions to certain foods.
Keep in mind that AGS may take weeks or even months to develop after a tick bite. It’s important to note that this test is not for people who’ve had severe allergic reactions. If you’ve experienced anaphylaxis or other serious symptoms, consult a healthcare provider or allergist immediately.
If your test results show a high level of alpha-gal antibodies in your blood, talk to a healthcare professional before making any dietary changes.
Why AGS testing matters
Understanding your sensitivity to alpha-gal can help you manage your diet, avoid allergic reactions and make informed choices about food and medications. However, IgE testing alone cannot diagnose allergies. AGS diagnosis typically requires both clinical history and laboratory testing, including for the IgE to alpha-gal and sometimes other confirmatory tests. Always discuss your results with a healthcare professional before making any changes to your diet.
If you suspect you might have AGS, visit Labcorp OnDemand to learn more. Knowing your status can help you stay safe, eat smart and live well.
