Alpha-gal allergy

Alpha-gal allergy


lpha-gal allergy is an unusual type of food allergy that can start with a tick bite. It involves an allergic reaction to a carbohydrate (a type of sugar) known as alpha-gal which is found in the muscles of mammals.

Allergy to alpha-gal is rare in the UK but reactions can sometimes be serious, so speak to your GP if you think you might have alpha-gal allergy.

What is alpha-gal allergy?

‘Alpha-gal’ is short for galactose-alpha-1,3-galactose. It’s a type of carbohydrate found in the muscles of mammals. Alpha-gal allergy starts when you are bitten by a tick which carries the alpha-gal molecule in its saliva.

When alpha-gal gets into your bloodstream, the immune system responds and makes antibodies that mark the alpha-gal molecule as ‘foreign’. The next time you eat meat from mammals such as lamb, beef or pork (but not poultry such as chicken or turkey), the body’s immune system wrongly identifies the alpha-gal in the meat as a threat. When this happens, the body releases chemicals, such as histamine, in response. It is the release of these chemicals that causes symptoms.

Which species of tick carry alpha-gal?

Not all species of ticks can cause alpha-gal allergy. Most known cases have been linked to the Lone Star tick which is found in southern and eastern areas of the United States. Cases of alpha-gal allergy have also been reported in many other countries including the UK, Australia, Sweden, Italy, Germany, Japan and South Africa, and involve different species of ticks.

What are the symptoms of alpha-gal allergy?

The symptoms of alpha-gal allergy are usually delayed, appearing three to eight hours after eating. This is unlike most other food allergies where symptoms usually come on within minutes. Most other food allergies are caused by proteins but alpha-gal is a carbohydrate, which might be why there is a delay in the allergic response.

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Mild to moderate symptoms may include:

  • a red raised rash (known as hives or urticaria) anywhere on the body
  • a tingling or itchy feeling in the mouth
  • swelling of the lips, face or eyes
  • stomach pain or vomiting.

More serious symptoms

The term for this more serious reaction is anaphylaxis (pronounced anna-fill-axis).

Most healthcare professionals consider an allergic reaction to be anaphylaxis when it involves difficulty breathing or affects the heart rhythm or blood pressure. Any one or more of the ABC symptoms above may be present.

In extreme cases there could be a dramatic fall in blood pressure. The person may become weak and floppy and may have a sense of something terrible happening. Any of the ABC symptoms may lead to collapse and loss of consciousness and, on rare occasions, can be fatal.

More serious symptoms are uncommon but possible. These may include:

  • AIRWAY – swelling in the throat, tongue or upper airways (tightening of the throat, hoarse voice, difficulty swallowing).
  • BREATHING – sudden onset wheezing, breathing difficulty, noisy breathing.
  • CIRCULATION – dizziness, feeling faint, sudden sleepiness, tiredness, confusion, pale clammy skin, loss of consciousness.

Getting a diagnosis

If you think you may be allergic to alpha-gal, see your GP who can refer you to a specialist allergy clinic if needed. They can find a clinic in your area from the British Society for Allergy and Clinical Immunology (BSACI).

It’s important to get a referral even if the symptoms were mild because it can be hard to tell if future allergic reactions could be more serious.

Once you get a referral, the consultant will discuss your medical history and symptoms with you. They might suggest skin prick, blood tests, and food challenge tests to help diagnose the allergy and work out how serious it may be.

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What can mean you’re at higher risk?

Some clues that you might be at higher risk of more serious reactions are:

  • you have already had a serious reaction, with any of the ‘ABC’ symptoms
  • you have asthma, especially if it is not well controlled
  • you have recently been bitten by a tick
  • you spend lots of time outdoors in wooded areas
  • you have reacted to a tiny amount of red meat.

If you have asthma, and it is not well controlled, this could make an allergic reaction worse. Make sure you discuss this with your GP or allergy specialist and take any prescribed medicines

Treating symptoms

If you have mild allergic symptoms, you may be prescribed antihistamine medicine to take by mouth. If you are at higher risk of anaphylaxis, you may be prescribed adrenaline to use in an emergency.

Adrenaline comes in pre-loaded adrenaline auto-injectors (AAIs) that are designed to be easy to use. Make sure you know how and when to use them. Ask your healthcare professional to show you how to use your specific brand of AAI. You can also find help and training videos on the manufacturer’s website where you can get a free trainer AAI to practise with.

You must have two AAIs with you at all times, as you may need to use a second one if your symptoms don’t improve after five minutes or get worse.

Avoiding tick bites

If you spend lots of time outside in wooded areas:

  • make sure you wear long sleeved tops and long trousers
  • use insect repellents to avoid being bitten
  • check your skin for any ticks when you get home
  • you can get special ‘anti-tick’ clothing that may offer further protection from bites.
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If you have been bitten by a tick, remove it carefully using fine-tipped tweezers.  Pull the tick directly upwards – avoid twisting or jerking so the mouth parts don’t break off in the skin. Once you have removed it fully, clean the area thoroughly with soap and water.

Avoiding alpha-gal in foods and medicines

Once you have been diagnosed with alpha-gal allergy, you will need advice from an allergy specialist about what you will need to avoid. Alpha-gal can be found in meat, gelatine, dairy products, and some medicines, but not everyone with alpha-gal allergy reacts to every food or product that contains it.

Most people only have reactions if they consume the food or product, but some people have reported reactions to fumes from foods when they’re being cooked.


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