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Alpha-gal syndrome: tick-borne allergy to red meat

Alpha-gal syndrome is an allergic response to mammalian proteins, triggered by repeated tick bites. It has been rapidly increasing in prevalence in the US since 2009, but is new to the UK. It is named after galactose-alpha 1,3-galactose, which is an oligosaccharide.

Although rare in this country, it has potentially life-threatening consequences and an unusual pattern of delayed anaphylaxis. This article highlights the key facts using a BJGP Clinical Practice article alongside information taken from the CDC (BJGP 2025;75(753):186, CDC - about alpha-gal syndrome).

This article was updated in October 2025.

You may find it helpful to read this alongside our articles on Lyme disease: NICE guideline and Tick-borne encephalitis.

Headlines

Urticaria occurs 2–6h after ingesting mammal products (including some medications).

Repeated exposure can lead to an increase in sensitivity and risk of anaphylaxis.

Can occur in travellers returning from the US and Scandinavia, but now also identified at sites in the UK.

Test for alpha-gal IgE serology and refer all suspected cases to an allergy specialist.

Treatment is avoidance of triggers, anaphylaxis prophylaxis (including avoiding exposure to tick bites and potential use of adrenaline auto-injectors) and antihistamines.

What is alpha-gal syndrome?

Alpha-gal syndrome is a serious IgE-mediated allergic response, usually to red meat, but it can also occur in response to other related products, including medications. It is the first known allergy where a carbohydrate is the source of an IgE-mediated response.

When a tick latches on and prepares to ingest a blood meal, it first has to inject a small amount of its saliva, containing an anticoagulant made from alpha-gal glycoproteins, to enable it to feed. This is the moment at which infection with Lyme disease or tick-borne encephalitis carried within the saliva can occur.

In people with genetic susceptibility, the alpha-gal glycoprotein can trigger a sensitisation response, and repeated exposure can then lead to an IgE-mediated immune response (type-1 hypersensitivity).

It was previously thought that only the lone-star tick (confined to the US) was associated with the syndrome, but it is now known that the UK tick species Ixodes ricinus is causing red meat food allergy in UK residents (BJGP 2025;75(753):186).

Prevalence

There have been 16 confirmed cases of UK-triggered alpha-gal syndrome since 2021 (all in Scotland) (BJGP 2025;75(753):186). Annual incidence is 0.38/100 000 people.

In the US, there have been more than 110 000 suspected cases in the past decade (CDC - about alpha-gal syndrome). However, because cases are difficult to identify and there is no formal reporting requirement, the CDC comments that this is likely to be an underestimate.

In Scotland, the confirmed cases mirror geographical patterns of Lyme disease (BJGP 2025;75(753):186). It is likely that the same will be true in England and Wales.

We should consider alpha-gal syndrome in people with relevant symptoms who have spent time in the countryside in:

Scotland (especially Fife, the Highlands and Tayside).
The New Forest.
Dartmoor.
Exmoor.
Thetford.
Cumbria.

Presentation

IgE-mediated allergic responses (including anaphylaxis) typically occur very rapidly after contact with the trigger (within 30 minutes).

In alpha-gal syndrome, although it is an IgE-mediated reaction, symptoms usually occur 2–6h after contact with the trigger (BJGP 2025;75(753):186). The delayed presentation is thought to be because digestion of the meat product is required before the alpha-gal oligosaccharide is released into the small bowel, triggering the immune response.

Symptoms include (CDC - symptoms of alpha-gal syndrome):

Urticaria.
Gastro-intestinal symptoms: nausea, vomiting, stomach pain, indigestion, diarrhoea.
Angioedema.
Respiratory symptoms, including cough and wheeze.
Hypotension.
Dizziness/faintness.
Anaphylaxis can occur.

As a patient becomes more sensitised to repeat exposure, the allergic reaction can become more severe and occur more rapidly (BJGP 2025;75(753):186).

Triggers

Alpha-gal is a carbohydrate found on the surface of the cells of most non-primate mammals.

Triggers
Food		Medication	Co-factors
High risk	Red meat: Beef, pork, lamb, venison, rabbit and other red meats. Includes stocks, broths, offal and food cooked in mammal fats such as lard.	Gelatine-containing vaccines: Zostavax, MMR. Gelatine-containing capsules. Pancreatic enzyme replacement. Magnesium stearate. Collagen supplements (OTC). Glycerin suppositories. Heparin. Cetuximab. Bovine or porcine heart valves. Gelatine plasma expanders. Some antivenoms.	Factors shown to increase the risk or severity of a reaction: NSAIDs. Alcohol. Exercise.
Medium risk	Dairy produce.
Low risk	Gelatine-containing foods. Carrageenan (a sea-weed derivative used as a thickener in some foods, and the only non-animal product on the list).
(CDC - products that may contain alpha-gal, BJGP 2025;75(753):186, Anaphylaxis UK - alpha-gal allergy)

Investigation and management

If we suspect alpha-gal syndrome, we should check alpha-gal-specific IgE serology to confirm.

Patients with suspected alpha-gal syndrome should be referred to an allergy specialist to confirm the diagnosis and identify which triggers need to be avoided (gov.uk - alpha-gal syndrome).

Management is by avoidance of tick bites, avoidance of triggers, and use of adrenaline auto-injectors and antihistamines.

Patients may need specific dietetic device to support them in this. Anaphylaxis UK has produced a patient information leaflet with more details: Anaphylaxis UK - alpha-gal allergy.

There is evidence of IgE cross-reactivity between alpha-gal and wasp venom. People who have alpha-gal syndrome are more likely to also be sensitive to wasp venom (CTA 2022;12:e12113).

Tick bite avoidance

(UKHSA - tips and tricks to stay safe from ticks, accessed April 2025)

We should give good advice about bite avoidance:

Dawn-to-dusk protection.
Long sleeves/trousers.
Adequate use of insect repellent.

Tick removal

After walking/hiking:

Check the body for ticks.
Remove ticks using fine-toothed tweezers/tick remover (see article on Lyme disease: NICE guideline to learn how to do this).

Alpha-gal syndrome: tick-borne allergy to red meat

A rare allergy to mammalian meat products, triggered by repeated tick bites.

Now known to be caused by UK-resident tick species.

Can cause a delayed anaphylaxis or severe IgE-mediated allergic reaction.

Treatment is with avoidance of triggers. Patients may require adrenaline auto-injectors and antihistamines.

Caution is needed with gelatine- or glycerol-containing medications.

Useful resources for patients:
Websites (all resources are hyperlinked for ease of use in Red Whale Knowledge)

Anaphylaxis UK - alpha-gal allergy factsheet

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