The GI Phenotype of Alpha-gal Syndrome (AGS)
A guide for people with alpha-gal syndrome
The GI phenotype (variant) of AGS
While GI complaints are not uncommon as part of an allergic reaction, 3–20% of patients with AGS report abdominal pain, nausea, emesis, diarrhea, heartburn in isolation of cutaneous, cardiovascular, or other signs/symptoms. This pattern of signs and symptoms complicates the diagnosis as well as management of AGS because the possibility of food allergy is not obvious, but patients can be severely affected. Indeed, examples of patients with AGS who have had exploratory surgery, removal of gallbladder or appendix, and partial pancreatectomy have been reported (57).
“…there are also patients who have episodes of abdominal pain without any skin involvement. Those cases are a problem because the possibility of food allergy is not obvious, and they can be severe… Other diagnoses that arise less commonly are arthritis and chronic pruritis. Distinguishing [AGS] from chronic hives can be challenging.” (6)
In addition to the classic allergy symptoms, some of our patients report significant gastrointestinal distress or gynecological symptoms. These symptoms can take the form of abdominal cramping and pain, heartburn, diarrhea, nausea or vomiting and in some cases uterine cramping with spotting. It is not uncommon for a patient who has anaphylaxis to lose consciousness while moving their bowels. Some patients have reactions that are characterized almost entirely of GI or gynecological symptoms while others may not experience these types of symptoms at all.
- Over 60% of people with AGS experience gastrointestinal symptoms (84,90,91,101), including one or more of the following:
- nausea
- diarrhea
- vomiting
- abdominal cramping
- abdominal pain
- The most common gastrointestinal symptom of AGS is cramping abdominal pain (57).
- Up to 20% of people with AGS have GI symptoms only (6,57,84).
- Some people with AGS are misdiagnosed with IBS or other gastrointestinal disorders (57).
- Immunoglobulin E to alpha-gal may be an underrecognized but frequent cause of gastrointestinal tract symptoms in eastern North America in the habitat distribution of the Lone Star Tick.
A group of experts convened by the NIH write:
Most α-Gal meat allergy reactions reported in the literature focus on the presentation of delayed pruritus, urticaria, angioedema, and anaphylaxis. More recently, and at the workshop, researchers have described reactions that manifest with abdominal pain—both in conjunction with skin reactions and as isolated gastrointestinal reactions (101).
Anecdotally, there are patients in whom the initial symptoms were restricted to the gastrointestinal tract but over a period of weeks or months, in some cases following additional tick bites, the symptomatology expanded to include the skin and/or anaphylaxis. It is, therefore, possible that isolated abdominal pain is an underreported and underdiagnosed feature of AGS (101).
D’Souza and Howarth write:
This case highlights a novel presentation of the alpha-gal allergy, a recently observed allergy that is increasing in prevalence. It is normally difficult to diagnose given the delayed reaction and generalized symptoms (114).
With individuals with recurrent gastrointestinal symptoms it is necessary to consider alpha-gal as a potential diagnosis. It is an allergy that can be easily missed and if not diagnosed can result in anaphylaxis (114).
I react gastrointestinally only. When I have reactions, the pain starts under my ribs, comes in waves, ten times worse than labor pain, and I get horrible chills and back aches from the pain and shivering. It’s awful. My last reaction in April landed me in the hospital and they gave me pain meds instead of an epi.
Abdominal cramps for hours, threw up sometimes, and four to five days of constipation, followed by uncontrollable diarrhea. Yep, I suffered that for three years. Three years of ultrasound, X-ray and MiraLAX double dose every day. Three years of toxic hell.
My GI doctor got bit by the tick and got it too. Only then did she call me in for the test.
It was always the upper abdomen, to the right side. It felt like a constant burning. It would last for a couple of hours, and there was nothing I could do to alleviate the pain. I had diarrhea every day. I was tested for gallbladder issues, pancreatitis, leukemia, everything except alpha-gal syndrome. I and was eventually diagnosed w IBS. I lost 25 lbs over a period of 6 months and didn’t need to. It took 10 yrs for an accurate diagnosis.
I have been symptom-free for 2 years since I eliminated all mammal meat, dairy, and anything else that might have a slight hint of any kind of mammal byproduct.
Did a tick bite cause your digestive issues?
“The current paradigm is that GI doctors should rarely think about food allergies, because those are problems of kids, not adults, and symptoms in allergies should occur reproducibly after exposure. That’s just not true in alpha-gal allergy. Mostly this has been reported in adults, and the delay of hours from eating the meat to reaction means that almost no patient can actually link the two (21).”
Alpha-gal syndrome can cause GI issues without classic, allergic symptoms like hives.
Learn more from the American Gastroenterological Association.
How to know if a tick bite caused your patients’ digestive problems
New American Gastroenterological Association
Clinical Practice Update on when to test patients for alpha-gal syndrome.
ACG Virtual Grand Rounds
Isolated GI Alpha-gal Meat Allergy: What Clinicians Need to Know
Isolated GI Alpha-Gal Meat Allergy: What Clinicians Need to Know
Sarah K. McGill, MD, MSc
ACOG Virtual Grand Rounds
August 19, 2021
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