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Imagine waking up in the middle of the night covered in hives, hours after a burger at a backyard cookout. Nothing new at dinner. No new soap or detergent. It happens again a few weeks later after pork chops. What's going on?
For a growing number of people, the answer starts with a tick bite. It's called alpha-gal syndrome, and because the reaction is delayed, it can take a while to figure out. If it sounds familiar, you're not imagining things, and there are clear steps you can take.
What Is Alpha-Gal Syndrome?
According to the CDC, alpha-gal syndrome (AGS) is a serious, potentially life-threatening allergy and tickborne disease. Alpha-gal is a sugar molecule found in most mammals, but not in people. After certain tick bites, some people's immune systems start reacting to it.
That means reactions can happen after eating red meat, such as beef, pork, lamb, or venison. The CDC notes that some people also react to dairy, and to certain medicines and other products made from mammals.
Which Ticks Are Linked to It?
In the United States, the CDC says AGS is most commonly associated with the lone star tick. A few cases have been reported after bites from blacklegged and western blacklegged ticks. Most reported cases occur in the South, East, and Central states.
It may be more common than you'd think. The CDC reports more than 110,000 suspected cases identified between 2010 and 2022, and estimates that as many as 450,000 people may be affected.
Why the Reaction Comes Hours Later
Most food allergies cause symptoms within minutes. Alpha-gal is different. The CDC says symptoms usually appear 2 to 6 hours after eating red meat or dairy. That delay is why so many people don't connect the reaction to dinner.
The CDC lists symptoms such as:
- Hives or an itchy rash.
- Nausea, vomiting, severe stomach pain, or diarrhea.
- Heartburn or indigestion.
- Cough, shortness of breath, or trouble breathing.
- Swelling of the lips, throat, tongue, or eyelids.
- Dizziness, faintness, or a drop in blood pressure.
A severe reaction, called anaphylaxis, needs emergency care right away.
Getting a Diagnosis
If this sounds like you, talk to your doctor or an allergist. The CDC says providers use a blood test that looks for antibodies your body makes in response to alpha-gal. Our post on how to read allergy blood test results explains what those numbers mean. Our post on which allergy test is right for you covers the other options.
The Best Protection: Prevent Tick Bites
The CDC says the best way to protect yourself and your family from AGS is to prevent tick bites. Its tick prevention guidance includes:
- Use an EPA-registered insect repellent, such as one with DEET, picaridin, IR3535, or oil of lemon eucalyptus.
- Treat clothing and gear with products containing 0.5% permethrin, or buy pre-treated items.
- Check your whole body after time outdoors, including under your arms, behind your knees, and in your hair.
- Shower within two hours of coming inside.
- Tumble dry clothes on high heat for 10 minutes to kill ticks on dry clothing.
- Check your pets, coats, and daypacks, since ticks can ride inside.
Spending time in the garden this season? Our post on gardening with allergies has more tips for enjoying the outdoors. For help with allergies at home, see our Practical Guide to Allergy-Free Living.
Your next step: Put repellent and a tick-check reminder by the back door. If you've had unexplained hives or stomach trouble hours after eating meat, write down what you ate and when, and share it with your doctor.
Wishing you the best of health,
Cheryl
Sources
- Centers for Disease Control and Prevention, About Alpha-gal Syndrome: https://www.cdc.gov/alpha-gal-syndrome/about/index.html
- Centers for Disease Control and Prevention, Symptoms of Alpha-gal Syndrome: https://www.cdc.gov/alpha-gal-syndrome/signs-symptoms/index.html
- Centers for Disease Control and Prevention, Preventing Tick Bites: https://www.cdc.gov/ticks/prevention/index.html
Medical Disclaimer: The information on this page is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider — such as an allergist or your primary care physician — before making changes to your allergy management plan, starting new treatments, or if you have questions about a medical condition. In the event of a severe allergic reaction or anaphylaxis, call 911 or your local emergency number immediately and use an epinephrine auto-injector if one has been prescribed.
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