Food Intolerance: Symptoms, Types, Treatment

Jenna Hilton
June 19, 2024

Many people suffer from digestive issues. Health experts recognize different medical concerns related to food depending on the severity of symptoms and what causes them. One of them is food intolerance.

This article explains what food intolerance is, how to diagnose it, and how to decrease or eliminate symptoms.

Food Intolerance: Symptoms, Types, Treatment

What is Food Intolerance?

Food intolerance is a genetic or acquired condition in which a person has an uncomfortable bodily reaction to a certain food or ingredient. Symptoms include abdominal pain, bloating, and gas. The condition is not life-threatening, but it can’t be cured permanently. Patients learn to manage and eliminate symptoms, and in some cases, the condition subsides or disappears completely with time.

What Is the Difference Between Food Intolerance and Food Allergy?

Patients often mistake a food intolerance for a food allergy because the symptoms overlap. Sometimes, even doctors have difficulty diagnosing the condition. The main differences include:

  • A food allergy triggers the immune system, while a food intolerance affects the digestive system.
  • A food allergy usually has a fast onset of symptoms, while a food intolerance can manifest hours after a meal.
  • Symptoms of a food allergy can be life-threatening; a food intolerance is uncomfortable but typically harmless.
  • Even a small amount of problematic food causes an allergic reaction; people with food intolerances may consume a small amount without experiencing any symptoms.

Note: Learn more about the differences between food allergy and intolerance in our comparison article.

Food Intolerance Types

Health experts recognize various food intolerances. The most common include:

  • Lactose intolerance – When a person’s digestive system can’t break down lactose, a type of sugar in milk and dairy products.
  • Gluten intolerance – When a person can’t fully digest gluten, a protein found in wheat, rye, and barley. Gluten intolerance is different from the more severe, autoimmune celiac disease.
  • Histamine intolerance – Impaired ability to digest histamine, a naturally occurring chemical found in various foods, including fish, cured and grated cheese, fermented cabbage, fermented meat, tomatoes, spinach, strawberries, shellfish, eggs, avocado, wine, beer, etc.
  • Fructose intolerance – Inability to break down fructose, a type of sugar in fruits, fruit juices, some vegetables (asparagus, peas), and honey. There are two types of fructose intolerance: dietary and hereditary.
  • FODMAP intolerance – Occurs when a person can’t properly digest FODMAPs, a group of fermentable carbohydrates. FODMAPs are found in various foods, including honey, apples, mango, avocado, pears, milk, yogurt, onion, garlic, legumes, and nuts.

Other food intolerances include adverse reactions to caffeine, alcohol, yeast, eggs, sulfites, and food additives.

Food Intolerance Symptoms

Food intolerance symptoms sometimes depend on the type of food intolerance, but many overlap. In most cases, the following symptoms are associated with specific conditions. The table below provides an overview of the main symptoms of different food intolerances.

Lactose intolerance symptoms  Gluten intolerance symptoms  Histamine intolerance symptomsFructose intolerance symptomsFODMAPs intolerance symptoms
Stomach painStomach painStomach painStomach painStomach pain
Stomach crampsBloatingBloatingBloatingBloating
VomitingJoint painNauseaNauseaConstipation
DiarrheaFatigueHeadache Fatigue
 AnxietyNasal congestion  
 Skin rashSneezing  

Does Food Intolerance Affect Your Weight?

Although there is no scientific evidence that directly links food intolerance and weight loss or weight gain, a dietary intolerance may indirectly lead to weight loss or weight gain. Here are some of the ways that this can happen:

  • Eliminating various foods from one’s diet may lead to malnutrition and hormonal imbalances, resulting in a change in weight.
  • Continuing to eat foods that are not adequately absorbed in the gut can lead to inflammation, possibly causing weight gain.
  • Bloating, a common food intolerance symptom, can cause perceived weight gain.

Note: Read our article on hormonal weight gain to learn how food intake, inflammation, hormonal activity, and weight gain are connected.

Causes of Food Intolerance

Scientists have limited knowledge about the prevalence and causes of food intolerances. The known causes include:

Enzyme Deficiencies

Some of the most prevalent food intolerances are caused by enzyme deficiencies, which inhibit the breakdown of a certain food ingredient and cause adverse reactions. These deficiencies can be genetic or acquired.

Here are the enzymes that can cause food intolerance:

  • Lactase – Helps to break down lactose in milk. Lactase deficiency leads to lactose intolerance, the most widespread food intolerance.
  • Diamine oxidase (DAO) – Helps to break down histamine. Low levels of this enzyme lead to histamine intolerance.
  • Aldolase B – Helps to break down fructose. This enzyme doesn’t work in people with inherited fructose intolerance.

Medical Conditions

Some medical conditions are known to increase the risk of developing a food intolerance. They include:

  • Celiac disease
  • Crohn’s disease
  • Impaired intestinal barrier (leaky gut)
  • Irritable bowel syndrome (IBS)
  • Chronic kidney disease
  • Viral hepatitis
  • Liver cirrhosis
  • Parasitic infections

Medications and Medical Interventions

Some medications and medical interventions can disrupt the gut microbiota, causing or increasing the risk of developing a food intolerance. They include:

  • Anti-inflammatory medications
  • Muscle relaxants
  • Blood pressure medications
  • Local anesthetics
  • Diuretics
  • Antidepressants
  • Antibiotics
  • Steroids
  • Surgery on the small intestine
  • Gastric bypass
  • Radiation therapy

How Is Food Intolerance Diagnosed?

Diagnosing food intolerance.

Diagnosing a food intolerance remains challenging due to a lack of specific symptoms and validated diagnostic tests.

In some cases, doctors first perform skin prick tests using food extracts or IgG blood tests to rule out allergies. They may perform other exclusion tests, such as a test for celiac disease.

They check whether family members have a similar condition and if the patient is taking medications that may inhibit enzyme activity.

Finally, they prescribe an elimination diet for two to eight weeks, during which the patient avoids potentially offending foods and tracks symptoms to confirm an intolerance.

Only lactose intolerance and hereditary fructose intolerance have a more straightforward diagnostic – the hydrogen breath test.

Food Intolerance Test

There isn’t a standard food intolerance test for every suspected food intolerance. It may include several diagnostic strategies, including exclusion testing (blood tests, skin prick tests, genetic testing, biopsies, etc.) and breath tests.

During a breath test, the patient drinks a solution with lactose or fructose and breathes in a balloon every 30 minutes for a few hours. The doctors evaluate the digestion of sugar (lactose, fructose, and sucrose) by analyzing the exhaled gas. The presence of hydrogen indicates bacterial overgrowth in the gut and their feeding on undigested sugars.

Elimination diet is the most common tool in diagnosing a food intolerance.

How Much Does a Food Intolerance Test Cost?

The cost of food intolerance testing depends on the strategies used to detect the exact cause of uncomfortable symptoms.

At Vibrant Vitality Clinic, our medical professionals provide allergy testing. For $299 patients receive a consultation, lab tests, and a follow-up to discuss results.

If you suspect a food intolerance and your symptoms include inflammatory skin reactions, schedule our special Skin Vibrancy Consultation, which includes food sensitivity testing.

Reach out to our health experts for a pricing package specific to your symptoms and needs.

Food Intolerance Treatment

In many cases, a food intolerance remains for life, but it is possible to fully eliminate the symptoms with a proper nutrition plan, dietary supplements, and stress management.

The key to reducing or eliminating symptoms is to remove or significantly reduce the trigger foods from your diet. Some patients find that consuming small amounts of such foods doesn’t cause adverse effects.

Lactose-intolerant patients can replace milk and dairy with lactose-free products or use lactase enzymes to help break down lactose. Probiotics and prebiotics also aid digestion.

In the case of FODMAPs and histamine intolerances, it is challenging to create a balanced diet because so many foods potentially contain the offending ingredients. Patients require the help of a medical professional to find a safe eating plan. They may also use enzyme supplements and other medications to help carbohydrate or histamine breakdown.

Stress is also known to exacerbate the body’s sensitivity to food triggers, so employing stress management techniques that lower cortisol may help improve symptoms.

What Happens If You Keep Eating Foods You Are Intolerant to?

In most cases, food intolerances aren’t life-threatening. However, if you continue eating the offending foods, your symptoms will remain, disrupting your daily life. Bloating and gas may keep you away from social activities. An upset stomach may prevent you from exercise, resulting in lower energy levels and possible weight gain, etc.

In some cases, undigested food further damages the small intestine, increasing the risk of more severe health complications, including inflammation, nutrient malabsorption, anemia, and osteoporosis.

When Should You Call a Doctor?

Immediately seek medical help if you experience severe allergic reactions:

  • Swollen mouth, tongue, or throat
  • Difficulty swallowing
  • Difficulty breathing
  • Extreme dizziness
  • Mental confusion
  • Extreme rash
  • Blue, grey, or pale skin
  • Fainting
  • Extreme abdominal pain
  • Severe diarrhea

We recommend consulting your healthcare provider about a perceived food intolerance even without experiencing severe adverse effects. Keep in mind that when people self-diagnose, in many cases they stop taking essential nutrients, leading to nutrient deficiencies, hormonal imbalances, and more serious health complications. ‌


Health organizations estimate that approximately 20% of the population suffers from a food intolerance. Eliminating potential food triggers from your diet for a limited period is one way to track symptoms and establish a potential causal link between certain foods and your symptoms.

However, self-diagnosis and self-treatment can lead to nutrient deficiencies. Working with a registered dietitian or another trusted healthcare provider is essential to effectively diagnose and tackle your medical concern.

Jenna Hilton
Jenna Hilton has been a practicing PA since 2009, specializing in Family, Internal Medicine and Medical Aesthetics. She attended Arizona State University where she received her Bachelor's Degree and graduated magna cum laude. She received her Master of Science degree in Physician Assistant Studies from A.T. Still University.

Jenna has been injecting neurotoxin and dermal filler since 2013. She received certification as a Master Injector in 2017 through Empire Medical in Los Angeles, California. She is currently working on a Fellowship Program in Anti-Aging and Regenerative Medicine through the American Academy of Anti-Aging Medicine. Her special interests include use of PLLA, Ablative/Non ablative skin resurfacing, PDO threads, hormone therapy and nutritional therapies to improve cellular regeneration and medically supervised weight loss.

Jenna Hilton believes in a multi-factorial approach, considering internal factors that accelerate aging and disease development. She always enjoys teaching. She co-founded Vibrant EDU courses at Vibrant Skin Bar and regularly performs one-on-one training with fellow injectors. She teaches Aesthetic and Advanced Injectable Courses at National Laser Institute. She has been named Preceptor of the Year and is an Adjunct Faculty Member at Midwestern University. She was born in Iowa, and lives with her husband and three children in Phoenix, AZ.

Featured Treatment:

Have a Question?

Vibrant Vitality Clinic - Advanced Hormone Replacement. Sexual Regenerative Medicine and Wellness Therapies.
Let's Connect!

Latest Blog Post:

Become a Member:

Search The Website:

Buy  Treatments online:

Connect with us:

4325 E Indian School Rd, Suite 130
Phoenix, AZ 85018
United States

(480) 422-2058

Monday - Friday: 9:00 am - 6:00 pm
Saturday: 9:00 am - 3:00 pm
Sunday: Closed

Follow us on Social media:

Connect With Us:
4325 E Indian School Rd Ste 130, 
Phoenix, AZ 85018

Find More From Us:

Vibrant Skin BarSHOP - Vibrant Skin Bar

Find Us On Map:

linkedin facebook pinterest youtube rss twitter instagram facebook-blank rss-blank linkedin-blank pinterest youtube twitter instagram