A new drug approved by regulators offers fresh hope for people living with a rare and potentially life-threatening meat allergy triggered by tick bites. The injectable medication, Xolair (omalizumab), was cleared by the US Food and Drug Administration in 2024 for a range of food allergies, including the condition known as alpha-gal syndrome. While it does not cure the allergy, it significantly reduces the severity of severe reactions after accidental exposure to meat.
First drug offers new hope
Xolair was first authorised more than two decades ago for patients whose asthma is difficult to control. It works by dampening the release of biological chemicals that drive inflammation and allergic responses. The FDA’s decision marked the first time a drug had been specifically approved for alpha-gal syndrome, a condition that has historically been managed only through strict dietary avoidance and carrying an epinephrine auto-injector for emergencies. Researchers are also investigating whether other existing biologic drugs that interfere with allergic signalling pathways could offer additional options. Dr Scott Commins, an alpha-gal syndrome researcher at the University of North Carolina, said: “There are certain [biologic drugs] out there nowadays that interfere with the allergic signaling. We think that if you were on one of those — or if you got one quickly enough after a tick bite — perhaps it could interfere with the entire allergic response process.”
The unusual mechanism behind the allergy
Unlike better-known tick-borne illnesses such as Lyme disease or Rocky Mountain spotted fever, alpha-gal syndrome is not caused by a bacterium or a virus. Instead, it arises when the human immune system mounts an allergic response to a specific sugar molecule called alpha-gal (galactose-α-1,3-galactose). This sugar is found in the meat of most mammals — including beef, pork, lamb, goat, rabbit and venison — but is absent in humans and other primates. It is also present in the saliva of certain ticks.
Under normal circumstances, eating alpha-gal is harmless because the digestive system processes it without triggering an immune reaction. However, when a tick bites through the skin, it can introduce the sugar directly into the bloodstream. The skin environment is particularly efficient at provoking allergic responses. “It turns out that the skin is a fantastic way to make an allergic response,” Dr Commins explained. “If this all happened orally, and we were eating alpha-gal like we do with steaks or barbecue, then we wouldn’t become allergic.”
Once introduced via the tick bite, the immune system develops specific antibodies (IgE) that identify alpha-gal as a foreign invader. Subsequent consumption of mammalian meat — which also contains the sugar — triggers a delayed allergic reaction, typically occurring three to six hours after the meal. This delay, often during the night, makes diagnosis challenging because sufferers may not immediately connect their symptoms to food eaten hours earlier. It can take weeks or even months for the problem to develop, and the severity of symptoms tends to increase over time.
In the United States, the primary culprit is the lone star tick, identifiable by a white dot on its back and common in the eastern and southern states. Its habitat has been expanding in recent years, with reports of the tick as far north as Martha’s Vineyard in Massachusetts and in the Great Lakes region. Researchers worry that other species, including blacklegged ticks, may also increasingly spread the condition. Across the Atlantic, the common UK tick, Ixodes ricinus (the sheep tick or castor bean tick), has been implicated in cases of alpha-gal syndrome among British residents. European research suggests this tick can also trigger alpha-gal sensitisation, and UK case reports have confirmed its role.
Diagnosis, foods to avoid and ongoing management
People typically seek medical help after experiencing symptoms such as hives, intense itching, swelling of the lips or eyelids, dizziness, difficulty breathing, or digestive issues including diarrhoea, stomach pain and vomiting. In severe cases, anaphylaxis — a life-threatening reaction involving a drop in blood pressure and rapid pulse — can occur. Doctors diagnose the allergy using a combination of the patient’s medical history, reported symptoms, and a blood test that detects the presence of alpha-gal antibodies. However, a positive test alone is not sufficient; symptoms must also be present. “The blood test in and of itself is great, but you can’t rely on that just for diagnosis. You need the actual symptoms too,” Dr Commins said. “In the allergy world, we have a lot of trouble with false positives on blood tests.” In the UK, the NHS recommends using an accredited laboratory for the IgE blood test, and notes that skin testing is not appropriate for this condition.
Once diagnosed, the primary treatment remains strict avoidance of mammalian meats — beef, pork, lamb, goat, rabbit, venison and organ meats. Some individuals may also need to avoid dairy products such as milk, cheese and butter, while those with particularly severe reactions must steer clear of foods containing gelatin (found in marshmallows and gummy bears) or carrageenan. Poultry, fish and eggs do not contain alpha-gal and are generally safe. One rare exception is meat from pigs that have been genetically modified to lack alpha-gal. These so-called “GalSafe” pigs, bred as part of an experimental program to harvest animal organs for transplantation, were approved for consumption by the FDA in 2020. Their meat is available from a company called Amaroo Hills. People with the syndrome must also be cautious about some medical products and implants, such as heart valves made from cow or pig parts.
For emergency treatment, an epinephrine auto-injector (such as an EpiPen) is often prescribed. The recently approved Xolair can reduce the severity of reactions after accidental exposure, but it does not reverse the underlying allergy. Researchers are exploring other avenues, including the use of existing biologic drugs and alternative approaches such as the Soliman Auricular Allergy Treatment (SAAT), a form of auricular acupuncture. A case series of 137 patients reported a high success rate, with many achieving complete remission and the ability to reintroduce mammalian meat. However, experts caution that further research is needed to confirm these findings.
For some people, the allergy can fade over several years. Dr Commins has observed this in about 15 to 20 per cent of his patients, but it depends critically on avoiding new tick bites. The estimated number of Americans who have developed the condition stands at roughly 450,000, according to a 2023 study by the Centers for Disease Control and Prevention. In the UK, alpha-gal syndrome is considered rare but awareness is growing. The incidence in Scotland, for example, mirrors the geographical patterns of Lyme disease, with a notable percentage of suspected cases testing positive for alpha-gal-specific IgE in certain NHS board areas. Risk factors include travel to the United States (particularly the southern, midwestern and mid-Atlantic regions), recent multiple tick bites, spending time outdoors in tick-prone environments, having a pre-existing allergy, and poorly controlled asthma. Using NSAIDs, consuming alcohol, and individual genetic factors may also play a role.
Prevention of tick bites remains the cornerstone of reducing risk. Health authorities recommend wearing protective clothing and using insect repellents containing DEET or permethrin when in areas of tall grass and woodland. After spending time outdoors, checking the whole body for ticks and removing them promptly without squeezing is essential. As the lone star tick continues to expand its range and Ixodes ricinus ticks are confirmed as vectors in the UK, awareness of tick habitats and consistent precautionary measures are vital for anyone who lives or works in tick-infested environments.