5 Signs and Symptoms That Could Indicate You Have a Food Intolerance

Food Intolerance

Are your meals causing digestive symptoms? Learn about the 5 key signs and symptoms of food intolerance and how to differentiate between food intolerances and allergies You’ll also get insights on what to do if you suspect you have a food intolerance.

Do you have strange symptoms that seem to come on when you eat certain foods? It could be a food intolerance, a growing concern among many, affecting approximately 20% of the population. The most common culprits include lactose, gluten, and casein, found in dairy products. These intolerances, unlike allergies, don’t trigger life-threatening reactions but can cause other symptoms.

What causes food intolerance? The lack of specific enzymes you need for food breakdown is the root cause in most cases. For instance, lactose intolerance stems from low lactase levels, which hinders lactose digestion and is one of the most common food intolerances in adults. But you can be intolerant to a variety of foods.

How Food Intolerances Differ from Food Allergies

Don’t confuse food intolerances with a food allergy. Food intolerance, distinct from an allergy, doesn’t involve the immune system.  Food allergies can be life-threatening, as they trigger an exaggerated immune reaction to specific foods, leading to potentially dangerous inflammation. In contrast, food intolerances, while not life-threatening, cause unpleasant, usually digestive upset, and can be quite disruptive.

Allergies are like the drama queens of the culinary world, provoking intense immune responses and potentially life-threatening situations. Food intolerances, on the other hand, are more like the annoying neighbors who disrupt your digestion party without causing life-threatening allergic reactions, like a food allergy can.

How do you know if you have a food intolerance? Identifying food intolerance requires professional confirmation, but certain symptoms might point you in the right direction. Here are five common signs that you could be intolerant to one or more foods.

Gas and Bloating

It’s normal to pass some gas each day. The average adult passes gas between 13 and 21 times daily. But food intolerances can cause more significant gas and bloating, sometimes accompanied by abdominal distension due to gas build-up.

If you’re intolerant to a food, you aren’t very efficient at breaking it down. So, it stays in your digestive tract longer and bacteria snack on the components you can’t break down – and when they do, they produce gas.

Symptoms vary from mild discomfort to severe bloating. Some people experience only mild discomfort after eating a small amount of the offending substance, while others suffer more intense gas and bloating when they consume even a bite.


The inability to break down certain food components, like lactose, can cause loose stools or diarrhea. The severity of the loose stools depends on the amount of the food you eat and how deficient you are in the enzymes that break it down. But it’s vital to consult a doctor as diarrhea can signal other conditions and you don’t want to think it’s a food allergy when it’s something else. If you have diarrhea, stay well-hydrated and replenish electrolytes, by drinking electrolyte-rich beverages. If it persists for more than a day, see your doctor.

Brain Fog

Some people with food intolerances develop brain fog. With brain fog, you might experience confusion, forgetfulness, and reduced mental clarity. You might also have mild memory problems, difficulty focusing, and mood swings. Although it’s unclear why food intolerances cause brain fog, experts believe the gut-brain connection likely plays a role. However, you should always rule out other causes if you have brain fog.

Skin Problems

Skin conditions like eczema and acne can be triggered or worsened by food intolerances.  If you have itchy skin or a rash, consult your doctor and maintain a food diary to identify triggers. Hives and swelling aren’t common with food intolerances but can occur with a food allergy. However, food intolerance can worsen pre-existing skin conditions such as psoriasis, atopic dermatitis, and acne.


While not definitively proven, evidence suggests that food intolerances, especially in people who already suffer from migraines, can trigger headaches. Foods like dairy, wheat, and certain grains are potential culprits, as are additives in processed foods. However, you can have headaches for other reasons too. Always talk to your doctor if you have new onset headaches or a change in the frequency or severity of your headaches.

What to Do If You Suspect a Food Intolerance

If you experience any of these symptoms, see a health professional. While you’re at it, start tracking what you eat and your symptoms.  An elimination diet may also help pinpoint specific intolerances. Here’s how to do one:

  • Plan Your Diet: Design a meal plan that avoids the foods you believe are triggering your symptoms. Ensure your meals remain balanced and nutritious to maintain your health during the process.
  • Keep a Food Diary: Maintain a detailed food diary, documenting everything you consume and the symptoms you experience afterward. This will help you and your healthcare provider track your progress.
  • Stick to the Plan: Adherence is key. Strictly follow your customized elimination diet for a few weeks.
  • Reintroduce Foods Methodically: Once your symptoms have improved or resolved, you can reintroduce the foods you eliminated, one by one.
  • Monitor and Evaluate: Continue tracking your food intake and any symptoms as you reintroduce foods. This step will pinpoint which specific items trigger adverse reactions.
  • Adjust Your Diet: With the guidance of your healthcare provider, create a long-term eating plan that avoids trigger foods, and keeps you healthy and comfortable.


Food intolerances may not be life-threatening, but they sure can throw a wrench into your digestive works. The primary suspects—lactose, gluten, and casein—found in dairy products are often the culprits behind these tummy troubles. So, be aware of that when planning an elimination diet.


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