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Alpha-Gal Syndrome: How A Tick's Saliva Can Make You Allergic To Meat


Rachael Funnell


Rachael Funnell

Digital Content Producer

Rachael is a writer and digital content producer at IFLScience with a Zoology degree from the University of Southampton, UK, and a nose for novelty animal stories.

Digital Content Producer

alpha gal syndrome symptoms

The lone star tick's saliva is thought to be a trigger for alpha-gal syndrome. Image credit: Melinda Fawver /

Alpha-gal Syndrome (AGS) is a rare allergy with unusual origins. Believed to follow bites from the lone star tick, AGS brings on an intolerance that would make BLT fanatics shudder.

People with AGS have to be very careful about their meat consumption as certain meats, including bacon, contain a substance that can trigger a deadly allergic reaction.


Also known as red meat allergy, AGS’s potentially life-threatening symptoms kick in following consumption of the sugar molecule alpha-gal (galactose-α-1,3-galactose) which is found in most mammals. This means that not all meat is off the menu because, as the Center for Disease Control and Prevention (CDC) helpfully points out, alpha-gal isn’t found in fish, reptiles, birds – or, in case you were interested, humans.

Alpha-gal syndrome symptoms

Should a lone star tick bite you and you develop AGS, symptoms may kick in around two hours after eating an offending ingredient. Symptoms range from a cough, nausea, and vomiting to hives, difficulty breathing, and a drop in blood pressure.

The severity of AGS ranges from person to person, so those with AGS may only have mild symptoms or could find themselves battling life-threatening symptoms like anaphylaxis.

Furthermore, not every exposure to alpha-gal will necessarily trigger AGS symptoms, but common culprits for the intolerance include milk, meat, and gelatin.

What causes alpha-gal syndrome

While lone star ticks are currently believed to be the most common source of tick-bite-related AGS, the possibility of other ticks triggering the condition hasn’t yet been ruled out. As such, avoiding tick bites is a decent way to swerve the condition if you’re not keen on giving up meat just yet.

The tick’s saliva is thought to be responsible for developing AGS as it contains proteins peppered with alpha-gal sugar molecules. This then leads to an IgE antibody-directed hypersensitivity against the sugar, so that future exposure to alpha-gal triggers an allergic reaction in the same way that a peanut would to someone with a nut allergy.

Alpha-gal advancements

Interestingly, The Atlantic reports that the biotechnology company Revivicor has somewhat serendipitously created AGS-friendly meat, as their genetically modified pigs are created to lack alpha-gal as it can also trigger organ rejection in humans.

By making "GalSafe pigs" lacking alpha-gal, they hoped to be able to transplant porcine organs into human hosts, and did just that during a heart transplant earlier this year.


Revivicor has so far sent out free samples of alpha-gal-free bacon, ham, and chops to people with AGS, but they are reportedly contemplating a mail-order service in the future.

For now, managing AGS is a case of keeping tabs on intolerances and adapting your diet accordingly, so if you’re concerned you might have it, the best next step is to discuss allergy testing with your healthcare provider.


All “explainer” articles are confirmed by fact checkers to be correct at time of publishing. Text, images, and links may be edited, removed, or added to at a later date to keep information current.


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