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Living with LymeAlpha-Gal Syndrome: The Tick-Bite Red Meat Allergy
For some people, a tick bite leads to an allergy to red meat and other mammal products. Here is what CDC says about alpha-gal syndrome and how it differs from Lyme disease.
Quick answer
Alpha-gal syndrome (AGS) is a serious, potentially life-threatening allergy that can develop after a tick bite. In the U.S. it is linked mainly to the lone star tick. People with AGS react to alpha-gal, a molecule in red meat and other mammal products, usually 2 to 6 hours after eating it. It is not Lyme disease (CDC).
- Alpha-gal is found in most mammals but not in people. It is also found in the saliva of some ticks (CDC).
- In the U.S., AGS is mainly associated with the lone star tick, and less commonly with blacklegged and western blacklegged ticks (CDC).
- Symptoms usually start 2 to 6 hours after eating red meat or dairy (CDC).
- CDC identified more than 110,000 suspected cases from 2010 to 2022. Because AGS is not nationally reportable, CDC says as many as 450,000 people may be affected.
- AGS should be managed with an allergist or other healthcare provider. For a severe reaction, seek emergency care right away (CDC).
What alpha-gal syndrome is
AGS is also called red meat allergy or tick bite meat allergy. When certain ticks bite, they can transfer alpha-gal into a person’s blood. In some people, the immune system then treats alpha-gal as a threat. Later, eating meat or other products from mammals can set off an allergic reaction (CDC).
Not everyone bitten by these ticks develops AGS, and CDC says it is not known why some people do and others do not. It can take weeks to months after a tick bite for AGS symptoms to appear.
The lone star tick connection
Most U.S. cases are linked to the lone star tick, which CDC describes as widely found in the Northeast, South and Midwest. CDC also lists it as a carrier of other infections, such as ehrlichiosis. Less often, blacklegged ticks and western blacklegged ticks have been linked to AGS.
The lone star tick does not spread Lyme disease. CDC states that lone star ticks are not able to transmit the bacteria that cause Lyme. Lyme is spread by blacklegged (deer) ticks and, along the Pacific Coast, western blacklegged ticks. Learn to tell them apart in ticks that carry Lyme disease.
Symptoms and delayed reactions
CDC lists these possible symptoms of an AGS reaction:
- Hives or an itchy rash
- Nausea or vomiting
- Severe stomach pain, heartburn or indigestion
- Diarrhea
- Cough, shortness of breath or difficulty breathing
- Drop in blood pressure, dizziness or faintness
- Swelling of the lips, throat, tongue or eyelids
- Anaphylaxis, a severe reaction involving several body systems
The delay is what makes AGS confusing. Symptoms usually start 2 to 6 hours after eating red meat or dairy, so a reaction in the middle of the night may not seem connected to dinner. Reactions can also differ from one exposure to the next, and people may not react to every alpha-gal product (CDC).
Call 911 for trouble breathing, swelling of the lips, tongue or throat, dizziness or fainting, or several symptoms at once, such as hives with vomiting. These can be signs of anaphylaxis. If a provider has prescribed epinephrine, use it as directed. CDC says people who use epinephrine should still get emergency care.
Products that can trigger reactions
CDC lists products that may contain alpha-gal. Not everyone with AGS reacts to all of them, so an allergist can help you work out your own triggers.
| Type | Examples CDC lists |
|---|---|
| Mammal meat | Beef, pork, lamb, venison, rabbit and other mammal meat, including organ meats |
| Milk products | Many people with AGS tolerate them, but some react |
| Other animal products (some people react) | Gelatin from beef or pork; foods made with mammal fat such as lard, tallow or suet; meat broth, bouillon, stock and gravy |
| Medicines and medical products | Some medicines and vaccines with ingredients such as gelatin, glycerin, magnesium stearate or bovine extract; heparin; pig or cow heart valves; some monoclonal antibodies and antivenoms |
CDC notes that poultry, fish and seafood, eggs, fruits and vegetables do not contain alpha-gal. CDC also says its list does not include every product that may contain it.
How it is diagnosed
A healthcare provider diagnoses AGS using a detailed history of your symptoms, a physical exam, and a blood test for IgE antibodies to alpha-gal. Skin testing for allergens such as pork or beef may also be used (CDC).
A positive blood test alone does not mean you have AGS. CDC notes false positives can happen, especially where lone star ticks are common, so results are weighed alongside your symptoms, the timing of reactions and your tick exposure.
Awareness is still growing. In a 2022 CDC survey of 1,500 U.S. health care providers, 42% had never heard of AGS (CDC MMWR, 2023). It can help to bring notes on what you ate, when symptoms began and any recent tick bites, and to ask whether seeing an allergist makes sense.
Where it is most common
Most U.S. cases are reported in southern, eastern and central states, where most lone star ticks live (CDC). Most reported cases are in adults, but people of any age can develop AGS. CDC notes hunters are at higher risk because of time spent in tall grass and wooded areas.
Living with alpha-gal syndrome
Day-to-day management is personal, so work with an allergist or other provider on what you need to avoid. CDC’s general advice includes:
- Read labels carefully. CDC notes cow’s milk is the only alpha-gal ingredient classed as a major food allergen, so ingredients like gelatin, lard or broth may not stand out. Check the full ingredient list.
- Tell your providers and pharmacist before any new medicine or vaccine.
- Have an emergency plan. If you are prescribed epinephrine, learn how and when to use it.
- Avoid more tick bites. CDC says new bites may reactivate reactions. Some people who avoid further bites may be able to tolerate alpha-gal products again, but that is an individual decision to make with your provider.
A registered dietitian can help you eat well while avoiding your triggers. Our food and Lyme guide explains when a referral may help.
Preventing tick bites
Preventing tick bites is the best protection against AGS (CDC). The same steps also lower your risk of Lyme disease:
- Use an EPA-registered repellent with DEET, picaridin, IR3535, oil of lemon eucalyptus, para-menthane-diol or 2-undecanone.
- Treat clothing and gear with permethrin.
- Shower and check your body for ticks after coming indoors.
See Lyme disease prevention for more, and what to do after a tick bite.
Alpha-gal vs. Lyme disease
| Alpha-gal syndrome | Lyme disease | |
|---|---|---|
| What it is | An allergy | A bacterial infection |
| Main U.S. tick | Lone star tick (less often blacklegged ticks) | Blacklegged and western blacklegged ticks. The lone star tick does not spread Lyme. |
| Main symptoms | Allergic reactions, usually 2 to 6 hours after eating mammal products | Fever, fatigue and often an expanding rash 3 to 30 days after a bite; later joint, nerve or heart problems if untreated |
| Diagnosis | History, exam and an alpha-gal IgE blood test, often with an allergist | Symptoms, exposure and sometimes blood tests (see Lyme testing) |
| Management | Avoiding triggers, an emergency plan and avoiding more tick bites | Antibiotics, usually for 10 days to 4 weeks |
It is possible to be bitten by different ticks over time, so tell your provider about every tick bite and every new symptom. For Lyme symptoms, see Lyme disease symptoms.
We are collecting real experiences about living with alpha-gal syndrome from people who have lived it, shared with their permission. As stories come in, they will appear here, clearly marked as personal experience rather than medical advice.
Food and allergy questions are part of living well after tick-borne illness. See Step 6: Live well with Lyme.
In the news: CDC blood donor study finds alpha-gal antibodies are common in some states.
Frequently asked questions
Is alpha-gal syndrome the same as Lyme disease?
No. Alpha-gal syndrome is an allergy linked mainly to lone star tick bites. Lyme disease is a bacterial infection spread by blacklegged ticks and treated with antibiotics.
Does the lone star tick cause Lyme disease?
No. CDC says lone star ticks are not able to transmit Lyme disease bacteria. They are, however, the tick most linked to alpha-gal syndrome in the U.S.
How long after eating meat does an alpha-gal reaction start?
CDC says symptoms usually begin 2 to 6 hours after eating red meat or dairy. Because of the delay, the link to a meal is easy to miss.
Can people with alpha-gal syndrome eat chicken or fish?
CDC lists poultry, fish and seafood, eggs, fruits and vegetables as foods that do not contain alpha-gal. Your allergist can confirm what is right for you.
Can alpha-gal syndrome go away?
CDC says some people who avoid more tick bites may be able to tolerate alpha-gal products again over time. Whether to try is an individual medical decision to make with your provider.