Wondering if gluten could be to blame for your bloating, stomach issues, brain fog, and increasing headaches? You’re not alone. Eighteen million Americans may be sensitive to gluten, but it can be difficult to determine if you could be part of that statistic.

It’s a little tricky: just because you have an intolerance to gluten doesn’t mean you will end up being allergic to wheat or diagnosed with Celiac, and it’s possible to be allergic to wheat without being sensitive to gluten. That’s why it’s so important to talk to your doctor about your symptoms and do the appropriate testing to uncover what is causing your issues.

For now, here are seven symptoms of gluten intolerance (also referred to as gluten sensitivity) as well as how to test for it, and what to do if you are gluten intolerant. 

7 signs you have a gluten intolerance.

Gluten intolerance can come in many forms, with the most serious resulting in a wheat allergy or Celiac disease. A wheat allergy is a type of immune response (also known as an IgE-mediated intolerance) triggered by ingesting products containing wheat proteins such as gluten. Celiac disease, on the other hand, is an autoimmune disorder that damages the villi in the small intestine. 

That said, symptoms of gluten sensitivity (also known as an IgG-mediated intolerance) may not present immediately after consumption, rather an onset of symptoms often occur within 24 to 48 hours of ingesting gluten, says Abby Vichill, M.S., RDN, L.D. So, when it comes to investigating gluten as a cause of health issues, give yourself time to see if these symptoms arise: 

1. Bloating.

Bloating generally refers to the feeling of the stomach being swollen or full of gas after you’ve eaten. Rocio Salas-Whalen, M.D., a board-certified endocrinologist at New York Endocrinology says bloating is one of the most common complaints she hears from patients who are sensitive or intolerant to gluten. 

2. Digestion issues.

Digestion issues such as gas, diarrhea, and constipation may also point to gluten intolerance. If you’re experiencing any of these symptoms regularly after consuming gluten, Salas-Whalen says you should definitely take note. 

“The majority of people who are gluten-sensitive regularly experience diarrhea, which can lead to larger issues like dehydration and fatigue,” she says. That said, one of the best things you can do is to be aware of how your body responds to certain foods. 

3. Stomach pain.

Much like bloating, Salas-Whalen says stomach pain is one of the most common complaints she hears from patients. 

“Although there can be a myriad of reasons for abdominal discomfort, you may have a negative reaction to gluten if you regularly experience this pain directly after consuming gluten without any other apparent causes,” she explains. 

4. Headaches and brain fog.

Chronic headaches and the inability to think clearly (aka, brain fog) are also common side effects associated with gluten intolerance. Interestingly, migraines seem to be more common among people with Celiac disease, IBD, and gluten sensitivity than in the control group, according to a 2013 study in the journal Headache. 

5. Skin issues.

Dry skin, itchy rashes, an increase in symptoms related to eczema and psoriasis, and acne are all common skin issues that may occur if you are gluten intolerant. It makes sense, as research has shown that half of participants who suffer from acne also suffer from gut issues. 

6. Symptoms of anxiety and depression. 

An increase in the symptoms associated with depression and anxiety were linked to eating gluten-containing foods, according to a 2014 study published in Alimentary & Pharmacology & Therapeutics. As we know, the gut-brain connection is very much real—an unhappy gut can lead to substantial changes in mood. 

7. Inflammation and joint pain.

People with gluten intolerance or sensitivity often report an increase in joint pain. According to the Arthritis Foundation, many patients with rheumatoid arthritis notice a decrease in joint-related pain after going gluten-free.