At least 25 million people in the US live with IBS.

IBS Facts and Statistics. International Foundation for Gastrointestinal Disorders.

The symptoms of IBS can overlap with other conditions.

Brush up on your knowledge and review the below diagnoses that could be mistaken for IBS.

Celiac disease

Celiac disease and IBS share some common symptoms, including abdominal pain, diarrhoea, and bloating.

Celiac Disease. National Institute of Diabetes and Digestive and Kidney Diseases.

Patel N, Shackelford KB. Irritable Bowel Syndrome. In: StatPearls. March 14, 2025.

But they are two distinct conditions. IBS can affect both the small and large intestine, while celiac disease only affects the small intestine.

Celiac Disease. National Institute of Diabetes and Digestive and Kidney Diseases.

CDC. Commonly Mistaken Conditions: Conditions commonly mistaken for IBD. June 12, 2024.

IBS does not cause damage to the digestive tract, while celiac disease can.

IgG4-RD 

Immunoglobulin G4-related disease (IgG4-RD) is a chronic inflammatory condition that causes fibrosis and organ dysfunction.

Bencardino S, Matichecchia CS, Fanizza J, et al. IgG4 in the gut: Gastrointestinal IgG4-related disease or a new subtype of inflammatory bowel disease. Autoimmunity Reviews. 2024;24(2):103720.

Unlike IBS, IgG4-RD is an autoimmune disease. Both conditions can cause abdominal pain and diarrhoea.

Hirano T, Kawakami Y, Nakabayashi S, et al. A Case of immunoglobulin G4-Related Gastrointestinal Disease Diagnosed From Persistent Diarrhea and Abdominal Pain. Gastro Hep Advances. 2023;2(8):1089–1092.

However, IgG4-RD only rarely affects the GI tract. 

Unlike IBS, IgG4-RD may be treated in the first instance with steroids.

Löhr JM, Vujasinovic M, Rosendahl J, et al. IgG4-related diseases of the digestive tract. Nature Reviews Gastroenterology & Hepatology. 2022;19:185–197.

Giardiasis

Like IBS, giardiasis may cause abdominal pain and diarrhoea.

Dunn N, Juergens AL. Giardiasis. In: StatPearls. February 12, 2024.

However, unlike IBS, giardiasis is caused by an infection. Many people with giardiasis also remain asymptomatic.

In the United States, those who travel overseas, frequently spend time outside, or work in daycares are most susceptible to the infection.

Unlike IBS, the standard treatment for Giardiasis is antibiotic therapy and rehydration. Treating giardiasis successfully is, however, becoming increasingly challenging.

Inflammatory bowel disease

Both inflammatory bowel disease (IBD) and IBS impact the gastrointestinal tract, and both can have a negative impact on quality of life.

They can also share symptoms like stomach pain and changes in bowel movements.

Diverticular disease

Like IBS, diverticular disease can cause constipation, diarrhoea, and abdominal pain.

Diverticular Disease. National Institute of Diabetes and Digestive and Kidney Diseases.

This occurs in diverticular disease when small pouches, or sacs, form and push outward in the wall of the colon.

One pouch is called a diverticulum, while multiple pouches are called diverticula.

Many people with the disease won’t experience symptoms.

Food poisoning

Food poisoning can cause IBS-like symptoms, including stomach pain, diarrhoea, cramps, and nausea.

CDC. Symptoms of Food Poisoning. January 31, 2025.

Unlike IBS, food poisoning is caused by ingesting certain germs, such as E. coli or Salmonella.

Lactose intolerance

Similar to IBS, lactose intolerance can cause bloating, abdominal pain, gas, and diarrhoea.

Malik TF, Panuganti KK. Lactose Intolerance. In: StatPearls. April 17, 2023.

As with IBS, these symptoms can occur after eating certain foods. In the case of lactose intolerance, symptoms may occur after eating foods that contain lactose, or milk sugar. Milk sugar is found naturally in many dairy products, including milk, cheese, and ice cream.

Lactose intolerance can also be managed through adjustments to diet.