Alpha-gal Syndrome

Alpha-gal syndrome (AGS) is a serious food allergy to red meat. It occurs most often in adults bitten by certain types of ticks. Symptoms range from mild to severe and can vary over time. Treatment involves avoiding triggers and managing symptoms.


What is alpha-gal syndrome?

Alpha-gal syndrome (AGS) is a serious and unusual food allergy to red (mammalian) meat. It occurs in people who have been bitten by certain types of ticks, usually if they’ve been bitten more than once. Ticks are mite-like parasites that feed on blood.

The saliva of some ticks contains a sugar molecule called alpha-gal (α-Gal). When alpha-gal enters the bloodstream, it can increase your sensitivity to red meat. This can trigger an immune system response. Your body reacts as if red meat is harmful, causing allergic symptoms. People with AGS may also react to other products containing alpha-gal, including medications and personal care products.

Currently, there isn’t a cure for AGS. Work with your healthcare provider to find ways to avoid triggers and stay healthy.

What is alpha-gal?

Alpha-gal is a carbohydrate (sugar) molecule found in most mammals. It doesn’t naturally occur in people.

What foods and products contain alpha-gal?

Alpha-gal can be found in:

  • Meat, including pork, beef, rabbit, lamb, goat, buffalo or venison.
  • Medical products and medications, including the cancer drug cetuximab.
  • Products made from mammals, such as gelatin and cow’s milk, as well as personal care and household items.

People with AGS may also react to products with carrageenan. This additive is often used to thicken and preserve food and drinks such as nut milks, meat products and yogurt.

Who gets alpha-gal syndrome?

Alpha-gal syndrome can affect anyone, including those who’ve never previously reacted to red meat. In most cases, it occurs in adults.

People throughout the U.S. have reported this syndrome. You’re more likely to develop AGS if you spend time outdoors in areas where ticks are present.


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What types of ticks can cause AGS?

In the U.S., alpha-gal syndrome is most often linked to the lone star tick. It’s the most common human-biting tick in the southeastern states, responsible for more than 90% of all tick bites. It’s also found in the eastern states and parts of the Midwest.

Other species that may cause alpha-gal syndrome include:

  • Blacklegged tick in the U.S.
  • Cayenne tick in Central America.
  • Asian longhorned tick in Asia.

Are there other conditions like alpha-gal syndrome?

Other allergies have symptoms that resemble alpha-gal syndrome, affecting the skin, heart, digestive system and lungs. But symptoms usually develop faster. Getting an accurate diagnosis is important so you can receive appropriate care.

Are there other names for alpha-gal syndrome?

Other names for alpha-gal syndrome are:

  • Alpha-gal allergy.
  • Mammalian meat allergy.
  • Red meat allergy.
  • Tick bite meat allergy.

How common is alpha-gal syndrome?

Cases of tick-borne disease doubled from 2004 to 2016, according to the U.S. Centers for Disease Control and Prevention (CDC). The exact number of people diagnosed with AGS is unknown.

Symptoms and Causes

What causes alpha-gal syndrome?

First described in 2009, alpha-gal syndrome (AGS) occurs due to bites from ticks that carry alpha-gal in their saliva. Delayed reactions may be because the body takes longer to digest carbohydrates than proteins, which trigger most other food allergies.

Healthcare providers don’t know the exact reason why alpha-gal triggers sensitivity to red meat or the cancer treatment cetuximab (Erbitux®). Researchers also don’t know why some people develop AGS, and others don’t.


When do symptoms of alpha-gal syndrome occur?

Symptoms occur two to six hours after eating meat or dairy. In some cases, symptoms can occur immediately after exposure to certain products, such as medications containing alpha-gal.

What are symptoms of alpha-gal syndrome?

Symptoms of alpha-gal syndrome range from mild to severe and can be life-threatening.

Skin reactions are common:

You may also experience gastrointestinal (GI) issues, sometimes as the only symptom:

Alpha-gal syndrome can also trigger lung symptoms:

Other symptoms include:

What can affect symptoms of alpha-gal syndrome?

Over time, you may experience different symptoms. Reactions can become more frequent or severe after new tick bites. In some cases, alcohol use, activity and exercise can also affect how your body responds to alpha-gal.

What if I take the cancer drug cetuximab (Erbitux)?

People with alpha-gal syndrome can have allergic reactions to this drug. Talk to your healthcare provider before taking any medications or vaccines.


Diagnosis and Tests

Why is alpha-gal syndrome difficult to diagnose?

It can be challenging to diagnose alpha-gal syndrome. Tick bites are painless, so many people who develop tick-borne illnesses often don’t realize they've been bitten.

Also, unlike other food allergies, delayed reactions to alpha-gal often occur late in the evening or in the middle of the night. And not every exposure to alpha-gal triggers a reaction or follows the same pattern.

These factors can make it difficult for you and your physician to figure out the connection to alpha-gal.

What tests can help diagnose alpha-gal syndrome?

To diagnose alpha-gal, your physician or allergist reviews your symptoms and health history and does a physical examination. Healthcare providers also use allergy testing to confirm a diagnosis, including:

  • Blood test that looks for immunoglobulin-E antibodies (proteins made by your immune system) to alpha-gal.
  • Skin prick test.

If you think you have AGS, talk to your healthcare provider as soon as possible. Early detection helps you avoid triggers and prevent complications.

Management and Treatment

Is there a cure for alpha-gal syndrome?

There isn’t a cure for alpha-gal syndrome. Early detection can help you and your healthcare provider develop a management plan specific to your needs.

Who might be on my treatment team for alpha-gal syndrome?

Alpha-gal syndrome requires the care of an allergist or other skilled healthcare provider. You may receive treatment from:

How is alpha-gal syndrome treated?

Treatment for alpha-gal (AGS) syndrome typically involves avoiding foods with alpha-gal and taking medications to manage symptoms that may occur with accidental exposure. Your healthcare provider can work with you to help you avoid products and medications containing alpha-gal.

Physicians may recommend rescue medications, such as antihistamines or an epinephrine (adrenaline) injector. Other treatments depend on your symptoms. Oral cromolyn solution can help with GI symptoms.


How can I reduce my risk of developing alpha-gal syndrome?

The most effective way to avoid getting AGS and other tick-borne illnesses is to prevent tick bites. The CDC recommends that you:

  • Avoid ticks:Know where they live and don’t go off the trails in wooded and grassy areas.
  • Cover up:Wear long-sleeved clothing. Tuck socks into your shoes or pants and use a hat and gloves when possible.
  • Use insect repellents:Use the U.S. Environmental Protection Approved (EPA)-approved insect repellents. Apply permethrin to clothing or buy pretreated clothing.
  • Do a tick check:Examine yourself and your pets for ticks after being outdoors. It’s also helpful to take a shower.
  • Remove ticks immediately:Use tweezers to grasp the tick near its head or mouth. Pull it out carefully without crushing it. Apply antiseptic to the area.

What foods and products should I avoid if I have alpha-gal syndrome?

Most people with alpha-gal syndrome need to avoid red meat in foods and other products. Everyone reacts differently to ingredients containing alpha-gal. Talk to your healthcare provider or allergist.

If you develop AGS, you may have to avoid:

  • Red meat: This includes beef, lamb, goat, venison, rabbit, buffalo or pork.
  • Products made from red meat: These may be food additives, milk, cream, ice cream, lard or cheese.
  • Personal care products made with meat: These include collagen, lanolin, gelatin or glycerin.
  • Other products: Talk to your healthcare provider about medications. Also discuss pig or cow heart valves, surgical mesh or certain vaccines that may trigger allergic reactions.

Outlook / Prognosis

What’s the outlook for alpha-gal syndrome?

The outlook for alpha-gal syndrome is good when you follow your treatment plan and avoid triggers.

Your healthcare provider can help you find ways to reduce the risk of allergic reactions. And take steps to avoid more tick bites because allergic reactions can get worse with repeated tick bites.

Living With

When should I seek care?

Contact an allergist or healthcare provider when you experience symptoms of AGS. Your provider will work with you to customize a care plan that meets your needs.

A note from Cleveland Clinic

Alpha-gal syndrome (AGS), a severe red meat allergy caused by a tick bite, can be challenging to diagnose and treat. If you experience symptoms, check in with your provider as soon as possible. Working together, you can find ways to stay safe and healthy.

Medically Reviewed

Last reviewed by a Cleveland Clinic medical professional on 12/02/2022.

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