Patient education: Alpha-gal syndrome (The Basics)

What is alpha-gal syndrome? — Alpha-gal syndrome is a specific type of allergy to red meat. It happens to some people after being bitten by a tick.

Certain types of ticks can pass something called "alpha-gal" to humans when they bite. Alpha-gal is a molecule that is also found in the meat that comes from some mammals. This includes beef, pork, and lamb. For some people, their body reacts in an abnormal way after being bitten by a tick. Their immune system makes proteins called "antibodies" against the alpha-gal molecules. Then, later, if the person eats red meat, they can have an allergic reaction to the alpha-gal in the meat. This can also happen if the person eats something else that comes from a mammal, like milk or gelatin.

In the US, "lone star" ticks are the most common cause of alpha-gal syndrome. A person usually needs to be bit more than once to develop this allergy.

What are the symptoms of alpha-gal syndrome? — The symptoms are similar to those of other food allergies. But unlike with other food allergies, symptoms usually take longer to happen. A person might not have symptoms until 2 to 8 hours after they have eaten red meat or a related food. Sometimes, people eat meat for dinner and then wake up in the night because they are having a reaction.

Mild symptoms can include:

●Hives, which are raised patches of skin that are very itchy (picture 1)

●Puffiness of the face, eyelids, ears, mouth, hands, or feet

Severe symptoms are also called "anaphylaxis." They can include:

●Swelling of the throat

●Nausea, vomiting, or diarrhea

●Wheezing, coughing a lot, or trouble breathing

●Feeling dizzy or passing out

●Death

Symptoms can differ from person to person.

Is there a test for alpha-gal syndrome? — Yes. If your doctor thinks that you might have alpha-gal syndrome, they will order a blood test. This test looks for the "IgE" antibody that the immune system makes when it has an allergic reaction.

Your doctor or nurse will also do an exam and talk with you. They might do other tests if they think that something else might be causing your symptoms.

How is alpha-gal syndrome treated? — The best treatment for a severe reaction is a medicine called "epinephrine." If you have had a severe allergic reaction, you need to keep epinephrine with you.

●Your doctor might prescribe a device called an "autoinjector" (for example, an EpiPen). This device has a shot of epinephrine that you can give yourself. If you have an autoinjector, keep it with you at all times. Use it right away if you think that you are having a severe allergic reaction. If you are not sure how severe your reaction is, it is still better to use the autoinjector, since symptoms can get worse quickly. After you use the autoinjector, call for an ambulance. That's because the symptoms might come back, and you might need more treatment in the hospital.

●Your doctor might also recommend a medicine called an antihistamine such as cetirizine (sample brand name: Zyrtec) or diphenhydramine (sample brand name: Benadryl). You can get these medicines without a prescription. They can help relieve mild allergy symptoms like itching and hives. They do not treat severe symptoms (anaphylaxis).

Most of the time, alpha-gal syndrome goes away over a period of years if you don't get more tick bites.

How can I prevent an allergic reaction? — The only way to prevent an allergic reaction is to completely avoid eating the things you are allergic to. With alpha-gal syndrome, this could include:

●Meat that comes from mammals, like beef, pork, and lamb

●"Organ meats," like kidney and liver

●Milk and dairy products

●Certain medicines and vaccines that contain gelatin

Not everyone reacts to all of these things.

Can alpha-gal syndrome be prevented? — The best way to prevent alpha-gal syndrome is to avoid tick bites.

To protect yourself:

●Wear shoes, long-sleeved shirts, and long pants when you go outside. Keep ticks away from your skin by tucking your pants into your socks.

●Wear light colors so you can spot any ticks that get on your clothes.

●Use bug spray to keep ticks away. On your skin, use bug sprays that have a chemical called "DEET." On your clothes and gear, use bug repellants that have a chemical called "permethrin."

●Check your body for ticks after being outdoors or with dogs. Check your scalp, waist, armpits, groin, and backs of your knees. If you have children, check them for ticks, too.

More on this topic

Patient education: Food allergy (The Basics)
Patient education: Anaphylaxis (The Basics)
Patient education: How to use an epinephrine autoinjector (The Basics)

Patient education: Food allergen avoidance (Beyond the Basics)
Patient education: Food allergy symptoms and diagnosis (Beyond the Basics)
Patient education: Anaphylaxis symptoms and diagnosis (Beyond the Basics)
Patient education: Anaphylaxis treatment and prevention of recurrences (Beyond the Basics)
Patient education: Using an epinephrine autoinjector (Beyond the Basics)