Alpha-gal Syndrome

Medically Reviewed By William C. Lloyd III, MD, FACS
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Beware of ticks warning sign in woods

You had a nice steak dinner four hours ago and are just getting ready for bed. Suddenly, you find yourself breaking out in hives, then feel your throat start to close up. You are in the throes of a severe, life-threatening allergic reaction, with no idea why, since as far as you know, you aren’t allergic to anything.

This situation has been playing out for at least the past decade, in different parts of the United States and world. Researchers have discovered that people are developing allergies to red meat or other meat products, usually after having previously been bitten by a Lone Star tick. The tick bite transmits a sugar molecule called alpha-gal, a common carbohydrate, but one which can prompt extreme allergic reactions in some people.

What treatments are available? How many people have this? And are you at risk for this condition? Here’s what is known so far about this mysterious, recently discovered syndrome.

What is alpha-gal syndrome?

Alpha-gal syndrome refers to the immune system response some people experience after exposure to a sugar molecule found in most mammals called alpha-gal for short (full name: galactose-alpha-1,3-galactose). This response can trigger a mild to severe allergic reaction to red meat, such as beef, pork or lamb, or to other products containing mammalian products, including dairy, cosmetics, medications, food flavorings, soaps and other products.

How is this allergic reaction created in humans? Transmission of alpha-gal syndrome in the U.S. appears to be mostly from bites by the Lone Star tick (so-called due to a white star-shaped mark that appears on the back of a female tick). The ticks pick up the alpha-gal molecules from the blood of the mammals they bite, such as cattle. Other parts of the world, such as Australia and Europe, are seeing transmission by other types of ticks. (An Australian doctor was the first to identify tick-induced mammalian meat allergy in 2007.)

Alpha-gal syndrome and Lyme disease

Alpha-gal does not appear to be related to Lyme disease, except that both are caused by tick bites. Lyme disease occurs after people are bitten by a blacklegged tick carrying a specific bacterium. Alpha-gal syndrome is an immune reaction to the sugar from the Lone Star tick. Although blacklegged ticks may confer the syndrome as well, the Lone Star tick appears to be the primary U.S. source of alpha-gal syndrome.

What are the symptoms of alpha-gal syndrome?

Symptoms of alpha-gal allergic response typically kick in 3 to 6 hours after exposure to red meat or mammalian products, which is unusual for a food allergy and can make diagnosis difficult. Signs include:

  • Hives, itching, itchy/scaly skin
  • Swelling of lips, face, tongue, throat, or other body parts
  • Headaches

About half of people who react to alpha-gal have anaphylactic reactions, which require treatment with epinephrine (such as Epi-Pens) and care in an emergency room. Symptoms of this life-threatening reaction include:

  • Rapid, weak pulse
  • Redness and warmth over your whole body.

How common is alpha-gal syndrome?

In the U.S., the syndrome has mostly been found where Lone Star ticks predominate, which is in the southeastern part of the country, as well as the east coast and south central regions. However, these ticks also are common as far north as Maine and as far west as central Texas. Deer that carry Lone Star ticks also appear to be moving further north and west due to climate change, potentially increasing the syndrome’s spread.

For now, it’s difficult to say how common alpha-gal syndrome is. It is a new syndrome and, as such, healthcare providers are not required to track it as a disease or syndrome. It may also be underdiagnosed. Recent estimates suggest more than 5,000 people may have it in the U.S.

Besides red meat, people with alpha-gal syndrome may react to the cancer drug cetuximab, as well as vaccines or other drugs made with gelatin (which is composed of animal byproducts).

How is alpha-gal syndrome treated?

The good news is that alpha-gal syndrome does not appear to be a long-term condition for most people. In general, symptoms fade within a couple of years, provided people have no further tick bites.

When it comes to treatment, however, there is no alpha-gal syndrome cure. Doctors treat the symptoms, such as prescribing antihistamines for mild allergic reactions and epinephrine injections for more severe responses.

To prevent future attacks, avoid tick-infested areas and, if you have the syndrome, stay away from foods or other products that can trigger a reaction.

To prevent tick bites:

  • When in wooded or grassy areas, cover up with shoes, long pants tucked into socks, long-sleeved shirts, hats and gloves
  • Use insect repellent on your skin containing a 20% or higher DEET concentration.
  • Permethrin-containing products can be applied to clothing, or you can buy clothes with this insect repellent already applied.
  • After being outside, always check yourself, your children, and your pets for ticks. Also, shower after being outside, using a washcloth to remove any unattached ticks.
  • If you find an attached tick, remove by grasping and pulling with tweezers near its head or mouth. Once removed, apply antiseptic, such as rubbing alcohol.

To prevent exposure to items containing red meat or meat-based ingredients:

  • Avoid all red meats, including beef, pork, lamb, rabbit, goat, buffalo and venison. Some people have reacted to turkey or chicken sausage when in pork casing. Poultry and seafood don’t have alpha-gal and should not cause a reaction.
  • Check labels on soups, stocks, gravy and other prepackaged products for meat-related flavorings and additives, which may be listed under such names as stearic acid, oleic acid, or tallow.
  • Avoid gelatin-containing items, such as Jell-O, marshmallows, jelly beans or some puddings; also watch for gel-cap medications.
  • The blood thinner Heparin also may cause a reaction, as it is derived from pig intestines.
  • Your doctor or allergist may have lists of products to avoid. Meat byproducts are widespread, including in cosmetics, soaps and other products, but can be difficult to identify.

Not everybody with alpha-gal syndrome will react to everything with meat in it. Also, some people may react to a red-meat meal one time, but not another time. Researchers are continuing to explore the illness, its causes and how best to combat it.

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2021 Feb 23
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