Can Lunch Meat Cause Diarrhea?

Diarrhea that develops after you eat lunch meat may be related to one of several health issues, such as a food allergy or intolerance, immune dysfunction, or even food poisoning. Lunch meats are often highly processed and can contain various food additives that may cause digestive upset. Because many of these conditions cause common, overlapping symptoms, you’ll need to see your doctor for an accurate diagnosis and treatment options. A food allergy or a condition that causes immune dysfunction may cause a severe allergic reaction that can be life-threatening.

Lactose Intolerance

Lunch meat probably isn’t a food you’d assume contains lactose, but many brands do. According to Cleveland Clinic, if you have lactose intolerance, you may need to avoid lunch meat. Lunch meats contain lactose and can trigger symptoms such as bloating, gas, diarrhea, stomach pain, nausea, and vomiting. Lactose intolerance is a common condition wherein your body cannot digest lactose, the sugar that’s found in milk. Symptoms occur when lactose is not absorbed by your body and makes its way into your colon, which takes a while — you may not experience symptoms until a day or two after you eat lunch meat containing lactose.

You can take an over-the-counter supplement of an enzyme called lactase (Lactaid) to help you digest lactose, according to the Canadian Digestive Health Foundation. Or you can avoid lunch meats that contain dairy ingredients altogether, by carefully checking the label. You can also opt for vegan lunch meat substitutes, which by definition don’t contain dairy.

Food Allergies and Immune Dysfunction

Lunch meats may contain various common allergens, according to the U.S. Department of Agriculture (USDA). Milk products are one such common allergen that are used in meat. And soy can be found in lunch meat as a color and flavor enhancer, according to research. Another condition that causes allergic symptoms is mast cell activation syndrome (MCAS), a form of immune dysfunction, notes research. In the case of MCAS, allergic reactions are triggered by harmless substances, so the trigger could be the meat or any of its added ingredients. Triggers can change over time, making them hard to identify, according to Mast Cell Action, a UK-based nonprofit. While MCAS has been considered a rare disease, the number of people being diagnosed is increasing, and it’s been connected to long COVID.

But since processed meats like lunch meat are regulated by the USDA, labels aren’t required to list the top nine allergens, as foods regulated by the U.S. Food and Drug Administration are, notes the National Celiac Association. The top nine allergens are wheat, milk, eggs, tree nuts, peanuts, fish, shellfish, soy, and sesame. Manufacturers under USDA regulation are encouraged to list top allergens, but it’s not required. Read the label closely and stick to brands that list allergens. You can also contact the manufacturer to make sure the lunch meat you’re buying wasn’t processed in a facility that shares equipment with products that contain allergens.

Food Intolerance

Aside from lactose intolerance, other food intolerances may trigger bouts of diarrhea after eating lunch meat. Two food intolerances that can trigger diarrhea that may be found in lunch meat are gluten and monosodium glutamate (MSG).

Gluten is a protein in wheat, barley, and rye (and sometimes oats) that can also be found in lunch meat and its plant-based alternatives, according to Cleveland Clinic. If you’re gluten intolerant, you shouldn’t eat lunch meat that lists it on the label (typically as hydrolyzed wheat protein) without first talking with your doctor. Food intolerances can be dose dependent, meaning that you might be able to tolerate smaller amounts, according to research. But if you have Celiac disease rather than an intolerance, you should avoid lunch meat with gluten, as it can cause damage to the small intestine, notes Cleveland Clinic.

MSG is a food additive that’s used as a flavor enhancer or to reduce the sodium content in processed meats, according to research. It can cause adverse reactions, including diarrhea, one research review notes.

Food Poisoning

Lunch meat that’s spoiled and has grown bacteria can cause food poisoning, notes Cleveland Clinic. So can products that were contaminated with bacteria from the meat itself, through processing, or during meal preparation, according to Yale Medicine. Food poisoning typically becomes symptomatic within hours or a few days of eating contaminated food, according to Mayo Clinic. Symptoms can include nausea, vomiting, diarrhea, fever, headache, and stomach pain.

Most people have mild cases and get better without treatment. But if your diarrhea lasts more than three days or causes severe dehydration, which can happen more easily if you’re also losing fluids through vomiting, see your doctor or seek emergency care. Other signs you should seek immediate care include: nervous system symptoms (blurred vision, skin tingling, muscle weakness); frequent vomiting; changes in thinking or behavior; and a temperature of 103 degrees F or higher.