Gluten intolerance is a fairly common concern. It’s characterized by adverse reactions to gluten, a protein found in wheat, barley, and rye.
There are several potential causes of gluten intolerance, including celiac disease, non-celiac gluten sensitivity, and wheat allergy.
All three forms can cause widespread symptoms, many of which have nothing to do with digestion.
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Available on the App StoreThis article covers the most common symptoms of gluten intolerance.
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Symptoms of celiac disease
Celiac disease is the most severe form of gluten intolerance.
It’s an autoimmune disease that affects about 1% of the population and may lead to damage in the digestive system.1 The global prevalence is 1.4% based on blood tests and 0.7% based on biopsy confirmation.
Celiac disease can cause a wide range of symptoms, including skin problems, gastrointestinal issues, mood changes, and more. Here are the most common ones.
1. Diarrhea, constipation, and smelly feces
People with celiac disease experience inflammation in the small intestine after eating gluten.
This damages the gut lining and leads to poor nutrient absorption, resulting in significant digestive discomfort and frequent diarrhea or constipation.
Frequent diarrhea can cause major health concerns, including loss of electrolytes, dehydration, and fatigue.
Pale and foul-smelling feces may also occur due to poor nutrient absorption. If you’re experiencing persistent digestive issues, it may be worth investigating gluten as a possible cause.
2. Fatigue
Feeling tired is common among people with autoimmune disorders, including celiac disease.
Several factors may contribute to fatigue in those with celiac disease:
- chronic pain
- sleep disruptions
- psychological conditions such as depression
Celiac disease may also be linked to a higher risk of iron deficiency anemia, which impacts the body’s ability to produce healthy red blood cells. This can cause decreased energy levels and persistent tiredness.
3. Skin reactions
Gluten intolerance can affect your skin.
A blistering skin condition called dermatitis herpetiformis is one manifestation of celiac disease. Although everyone with celiac disease is sensitive to gluten, some don’t experience digestive symptoms — their celiac disease shows up primarily through skin problems.
Several other skin conditions have shown improvement on a gluten-free diet, including:
- Psoriasis — an inflammatory condition characterized by scaling and reddening of the skin
- Alopecia areata — an autoimmune disease that appears as non-scarring hair loss
- Chronic urticaria — a skin condition with recurrent itchy pink or red lesions
4. Depression and anxiety
Depression affects about 6% of adults each year. The symptoms — often involving feelings of hopelessness and sadness — can significantly impact daily life.
People with digestive issues tend to be more prone to both anxiety and depression than those without underlying conditions. This is especially common among people with celiac disease.
There are a few theories about how gluten intolerance may drive depression:
- Atypical serotonin levels — Serotonin is a neurotransmitter that allows cells to communicate. Decreased levels have been associated with depression.
- Gluten exorphins — These peptides form during the digestion of some gluten proteins. They may interfere with the central nervous system and raise the risk of depression.
- Changes in the gut microbiota — Increased harmful bacteria and decreased beneficial bacteria may affect the central nervous system and increase depression risk.
If you’re struggling with mood issues alongside digestive symptoms, consider talking to your doctor about gluten testing.
5. Unexplained weight loss
Unexpected weight change is often a cause for concern. While it can stem from various reasons, unexplained weight loss is a common side effect of undiagnosed celiac disease.
Suggested read: The 8 Most Common Food Intolerances and Symptoms
In one older study, two-thirds of celiac disease patients had lost weight in the 6 months leading up to their diagnosis.
Weight loss may be explained by digestive symptoms coupled with poor nutrient absorption.
6. Iron-deficiency anemia
Iron deficiency is the most common nutrient deficiency and accounts for 50% of all anemia cases worldwide.
Symptoms of iron deficiency include:
- low blood volume
- fatigue
- shortness of breath
- dizziness
- headaches
- pale skin
- weakness
In celiac disease, nutrient absorption in the small intestine is impaired, reducing the amount of iron absorbed from food.
Iron deficiency anemia may be among the first symptoms of celiac disease that a healthcare professional notices. Research suggests iron deficiency is significant in both children and adults with celiac disease.2
Suggested read: Vitamin B12 Dosage: How Much Do You Need Per Day?
7. Autoimmune disorders
Celiac disease is an autoimmune disease that causes your immune system to attack your digestive tract after you consume gluten.
Having this autoimmune condition makes you more prone to other autoimmune diseases, such as autoimmune thyroid disease. And autoimmune thyroid disorders may be a risk factor for developing emotional and depressive disorders.
Celiac disease is more common in people who have other autoimmune diseases, including type 1 diabetes, autoimmune liver diseases, and inflammatory bowel disease.
8. Joint and muscle pain
People experience joint and muscle pain for numerous reasons.
There’s a theory that those with celiac disease have a genetically determined oversensitive or overexcitable nervous system. This may mean they have a lower threshold to activate sensory neurons that cause pain in muscles and joints.
9. Leg or arm numbness
Another symptom of gluten intolerance is neuropathy — numbness or tingling in the arms and legs.
This condition is common in people with diabetes and vitamin B12 deficiency. It can also be caused by toxicity and chronic alcohol misuse.
However, research suggests that people with celiac disease could also be at a higher risk of developing this neuropathy, possibly caused by the presence of certain antibodies.
Summary: Celiac disease is an autoimmune disorder associated with a long list of symptoms, including diarrhea, constipation, fatigue, chronic pain, depression, anxiety, unintentional weight loss, and more.
Symptoms of non-celiac gluten sensitivity
Although celiac disease is the most severe form of gluten intolerance, 0.5–13% of people may have non-celiac gluten sensitivity (NCGS) — a milder form that can still cause symptoms.3
Meta-analyses suggest that during controlled challenge studies, 16–30% of people who self-report gluten sensitivity have symptoms specifically triggered by gluten.
Here are the most common symptoms of non-celiac gluten sensitivity.
1. Bloating
Bloating is when your belly feels swollen or full of gas after eating. It can be uncomfortable and frustrating.
Although bloating is very common and has many explanations, it may also be a sign of gluten intolerance.
Feeling bloated is one of the most common concerns among people sensitive or intolerant to gluten. One study showed that 87% of people with suspected non-celiac gluten sensitivity experienced bloating.
2. Diarrhea and constipation
Occasional diarrhea and constipation are normal, but regular occurrences may be cause for concern.
For people with gluten sensitivity, consuming foods that contain gluten can trigger digestive issues.
More than 50% of gluten-sensitive individuals regularly experience diarrhea, while about 25% experience constipation.
3. Stomach pain
Abdominal pain is very common and can have numerous explanations.
However, it’s also the single most common symptom of gluten intolerance.
It’s estimated that up to 83% of those with gluten intolerance experience abdominal pain and discomfort after eating gluten.
4. Headaches
Many people experience headaches or migraine attacks occasionally. Migraine is a common condition, affecting roughly 1 in 6 adults in the United States.
Still, studies have shown that gluten-intolerant people may be more prone to migraine episodes than others.
If you have regular headaches without any apparent cause, you could be sensitive to gluten.
5. Fatigue
Feeling tired is very common and usually not linked to any specific condition. But if you constantly feel very tired, you should explore potential underlying causes.
Gluten-intolerant people are prone to fatigue and tiredness, especially after eating foods that contain gluten.
According to one study of 486 people with non-celiac gluten sensitivity, 64% reported experiencing tiredness and fatigue.
6. Depression and anxiety
Anxiety disorders affect approximately 33% of people worldwide.
Anxiety involves feelings of worry, nervousness, unease, and agitation. It often goes hand-in-hand with depression.
People with gluten intolerance seem more prone to anxiety and depression than those without underlying conditions.
In one study, up to 40% of people with self-reported gluten sensitivity stated they regularly experienced anxiety.
Several studies have shown that people with depression and self-reported gluten intolerance say they feel better with a gluten-free diet and want to continue it, even if their digestive symptoms aren’t entirely resolved.
That suggests gluten exposure alone may induce feelings of depression, irrespective of digestive symptoms.
7. Pain
Gluten exposure may cause inflammation in gluten-sensitive people.
The inflammation may result in widespread pain, including in the joints and muscles.
People with gluten sensitivity also seem more likely to experience arm and leg numbness. While the exact cause remains unknown, older studies have linked this symptom to the presence of certain antibodies related to gluten intolerance.
Suggested read: The 8 Most Common Food Allergies and Their Symptoms
8. Brain fog
“Brain fog” refers to the feeling of being unable to think clearly. People describe it as:
- being forgetful
- having difficulty thinking
- feeling “cloudy”
- experiencing mental fatigue
Having a foggy mind is a common symptom of gluten intolerance, affecting nearly 40% of gluten-intolerant people.
This symptom may be caused by a reaction to certain antibodies in gluten, but the exact reason is unknown.
Summary: Non-celiac gluten sensitivity is a form of gluten intolerance that can cause headaches, depression, anxiety, brain fog, fatigue, pain, and digestive problems.
Symptoms of wheat allergy
Wheat allergy is a type of food allergy that causes the body’s immune system to react to certain proteins found in wheat, including gluten and other compounds.
Wheat allergy is more common among children than adults. Approximately 65% of children outgrow wheat allergies by age 12.
Here are the most common symptoms of wheat allergy.
1. Skin rash
Like other types of gluten intolerance, wheat allergies may be associated with certain skin conditions.
Wheat allergies can cause hives — a type of skin rash characterized by itching, redness, and inflammation.
Typically, this reaction sets in shortly after eating wheat products and slowly subsides on its own over time.
2. Digestive issues
Studies show that people allergic to wheat often experience digestive symptoms such as:
- nausea
- vomiting
- stomach cramps
- diarrhea
Food allergies can also trigger bloating, pain, and indigestion. This is due to the body’s immune response, which is triggered when an allergen like wheat is consumed.
3. Nasal congestion
Sneezing, nasal congestion, and a runny nose can be signs of a wheat allergy.
These symptoms are particularly common in people with Baker’s asthma — an allergic condition caused by frequently breathing in bread flour, resulting in increased sensitivity to wheat or other grains.
Suggested read: 9 Signs and Symptoms of Vitamin B12 Deficiency
According to one study of 162 bread factory workers, nearly 89% of those who experienced symptoms of Baker’s asthma also reported nasal symptoms like congestion.
4. Anaphylaxis
Anaphylaxis is a severe allergic reaction that can be life-threatening if left untreated.
It can cause a range of serious symptoms including swelling, hives, nausea, vomiting, and difficulty breathing after exposure to an allergen like wheat.
Although symptoms usually begin within minutes of exposure, they may also occur up to an hour later.
Treatment generally involves the use of epinephrine, a medication injected directly into the skin after the onset of anaphylaxis.
Summary: Wheat allergy is a type of food allergy that may cause skin rashes, digestive issues, nasal congestion, and anaphylaxis.
When to see a doctor
If you regularly experience some of the symptoms listed above without an apparent cause, you may be reacting to gluten in your diet.
Important: Screening for celiac disease must occur before starting a gluten-free diet, since diagnostic testing becomes unreliable once someone stops eating gluten.4
A healthcare professional can perform blood tests for celiac disease antibodies and, if needed, refer you for an intestinal biopsy to confirm the diagnosis.
For non-celiac gluten sensitivity, there are no validated biomarkers yet. Diagnosis typically involves ruling out celiac disease and wheat allergy, then monitoring symptoms on a gluten-free diet.
If you’re considering a gluten-free diet, talk to your doctor first to get proper testing.
Singh P, Arora A, Strand TA, et al. Global Prevalence of Celiac Disease: Systematic Review and Meta-analysis. Clin Gastroenterol Hepatol. 2018;16(6):823-836.e2. PubMed ↩︎
Montoro-Huguet MA, Belloc B, Domínguez-Cajal M. Small and Large Intestine (I): Malabsorption of Nutrients. Nutrients. 2021;13(4):1254. PubMed ↩︎
Catassi C, Elli L, Bonaz B, et al. Diagnosis of Non-Celiac Gluten Sensitivity (NCGS): The Salerno Experts’ Criteria. Nutrients. 2015;7(6):4966-4977. PubMed ↩︎
Leonard MM, Sapone A, Catassi C, Fasano A. Celiac Disease and Nonceliac Gluten Sensitivity: A Review. JAMA. 2017;318(7):647-656. PubMed ↩︎
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