Alpha-Gal Allergy

Medically reviewed by Elaine K. Luo, MD on July 3, 2017Written by Kathryn Watson


Galactose-alpha-1,3-galactose (alpha-gal) is a carbohydrate that is found in the cells of many animals that humans eat. It’s contained in the cells of mammals as well as some poultry. As a result of autoimmune responses, some people become allergic to alpha-gal.

People with this allergy may experience mild discomfort after eating meat, or they may have a dangerous reaction that leaves them unable to breathe. The spectrum of reactions to alpha-gal varies, but most of instances of this allergy are triggered by tick bites.

Causes and risk factors

People aren’t born with an allergy to alpha-gal. Almost everyone in who has an alpha-gal allergy developed it as an adult, though children can get it. Bites from the lone star tick have been shown to cause alpha-gal allergies. Some research argues that ticks are the only real cause of this sort of allergy. Ticks contain alpha-gal, and the tick bite triggers your immune system to react to alpha-gal as a defense mechanism.

The antibodies that your body makes to protect you from the tick bite are in your body’s system from then on. These same antibodies that your body creates to help your body react properly to the parasitic tick bite will then combat alpha-gal when you eat meat that contains it.

Living in areas where lone star ticks are prevalent puts you at a higher risk of this happening. The lone star tick lives primarily in the southeastern and eastern United States.

Signs and symptoms

The symptoms of meat allergies are similar to those of other kinds of allergies. Hives, headaches, and a runny nose after eating meat from a mammal are all common with alpha-gal allergy. But allergic reactions can vary greatly on a case-by-case basis, and your allergic reaction might look different from someone else’s.

Alpha-gal allergy can cause:

  • runny nose or congestion
  • diarrhea
  • nausea
  • sneezing
  • hives
  • asthma
  • anaphylaxis, a severe reaction that shuts down your body’s ability to breathe

Treating and preventing alpha-gal allergy


Allergic reactions to alpha-gal can be treated with an over-the-counter antihistamine such as diphenhydramine (Benadryl). Stronger reactions provoked by alpha-gal might need to be addressed with epinephrine.

Researchers don’t know yet how long after the tick bite the allergy can last. Right now, they don’t believe that it’s chronic. However, they do point out that additional tick bites can bring the allergy back even if it becomes inactive.

Identifying diet triggers

If you find out that you have an alpha-gal allergy, get to work identifying your triggers. While all sorts of red meat might need to stay off your table for the time being, there could be other trigger foods that will provoke your symptoms. Dairy products and some poultry products can contain alpha-gal.

People with any serious food allergy should be hyperaware of what’s in their food. If your symptoms are serious when you have an allergic reaction, you might want to start carrying a portable epinephrine treatment (such as an EpiPen) in case of an emergency. Make sure that your family, co-workers, and people you live with know what to do if you have a severe allergic reaction, and go over possible action plans with them before you even need their help.


Make yourself harder for ticks to target by using insect repellant when exploring wooded areas, and wearing long sleeves and long pants whenever possible if you’re in the woods. You also want to check your hair, scalp, arms, and ears frequently for ticks that may be trying to latch on to your skin. Know the proper way to remove and dispose of a tick if you do get bitten.


The most serious complication from alpha-gal allergy, and any allergy, is the risk of anaphylaxis. A person who has been bitten by a tick might not know that they have developed an alpha-gal allergy until they’re experiencing symptoms. Even then, they might not draw the conclusion that the tick bite is related to this new allergy.

How it’s diagnosed

An alpha-gal allergy is diagnosed the way most allergies are. An allergist will perform tests on your body to see how it reacts to alpha-gal.

Using a blood test and possibly a skin reaction test, your allergist will be able to see if your body views alpha-gal as a threat. If exposure to alpha-gal causes a histamine reaction in your blood, your allergy test to alpha-gal will show as positive.


There is a lot that we don’t know yet about the causes, treatment, and duration of alpha-gal allergies. If you’d been bitten by a tick, be aware that an alpha-gal allergy could develop, and try to document any symptoms that you have. Symptoms could develop quickly — within three to six hours of being bitten.

There’s a good chance that alpha-gal allergies don’t last forever. Speak to your doctor if you have a reason to suspect that you’ve been bitten by a lone star tick. Identifying this allergy can only help you to better adjust your diet and make lifestyle choices that will prevent a dangerous allergic reaction.

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