A Quick Reference Guide to Common Conditions Associated with Gut Health

Osmosis Team
Dec 27, 2023

Effectively diagnosing common conditions is crucial for delivering quality care and maintaining a patient's quality of life. In today's Osmosis from Elsevier blog, we're exploring gut health, microbiomes, dysbiosis, and common GI conditions including symptoms, diagnosis, and treatments.


When you hear the term “gut,” you probably immediately think of your stomach and intestines. However, your gut, or gastrointestinal (GI) tract, actually begins at your mouth, continues to the anus, and includes vital organs like the liver, gallbladder, and pancreas. Let’s discuss some common conditions related to gut health and where they occur within your GI tract.

An illustration of good and bad organisms in our gut flora.


Let’s start with a condition that can affect any part of the GI tract: dysbiosis. Dysbiosis is a broad term used to describe an imbalance of microorganisms within a microbiome, which is a collection of microorganisms existing within a certain environment. In the human body, important microbiomes are found primarily in the GI tract and skin. The GI tract microbiome starts developing at birth and is influenced by an individual’s environment and diet. 

In general, the GI tract’s microbiome consists of a variety of beneficial bacteria, viruses, and fungi. It plays a pivotal role in safeguarding against against pathogens while also supporting immune and metabolic processes. Dysbiosis occurs when these beneficial microorganisms become imbalanced either through an increase or decrease in their number and/or changes to their composition or distribution. This imbalance allows troublesome microorganisms to prosper and disrupt normal processes. 

Examples of specific types of dysbiosis include small intestinal bacterial overgrowth (SIBO), large intestinal bacterial overgrowth (LIBO), and small intestinal fungal overgrowth (SIFO). Dysbiosis has a variety of causes, including antibiotic use; psychological, physical, or oxidative stress; an unbalanced diet (i.e., diet lacking nutrients); and alcohol abuse.

Signs and symptoms of dysbiosis are typically mild and depend on which part of the GI tract is involved. If the oral cavity (mouth) is affected, it may manifest as tooth decay, cavities, a sore throat, and bleeding gums. Conversely, if the stomach or intestines are affected, symptoms may include bloating, abdominal discomfort, belching, nausea, or bowel changes. 

If left untreated, dysbiosis can even lead to chronic conditions like inflammatory bowel disease, type 2 diabetes mellitus, cardiovascular disease, and colorectal cancer, making early detection and management crucial in mitigating the risk of more serious health issues.

Diagnosing dysbiosis typically includes a thorough history, physical examination, and relevant lab tests (e.g., CBC, CMP, vitamin levels), and diagnostic tests. Diagnostic tests that can confirm dysbiosis and help identify specific types of dysbiosis (e.g., SIBO, LIBO, etc) include a hydrogen breath test, organic acid test, and comprehensive digestive stool analysis (CDSA). 

Treatment of dysbiosis is tailored to an individual’s needs and involves reestablishing the GI microbiome. Treatments may include a combination of dietary changes, probiotic supplements, and lifestyle modifications. In some cases, individuals may need a fecal microbial transplant (FMT) treatment, which is when stool from a healthy individual is transferred to an individual with dysbiosis, with the aim of reintroducing beneficial microorganisms and fostering a healthier microbiome.

An illustration of the inside of a person's mouth, exposing the inside of their bottom lip where sores caused by dysbiosis are present.

Angular Cheilitis and Stomatitis 

Now let’s take a look at a common condition affecting the oral cavity (mouth), which includes your lips, teeth, gums, hard and soft palates, part of the tongue, salivary glands, and the oral mucosa that lines most of these structures. Two common conditions can affect the oral cavity: angular cheilitis and stomatitis. Angular cheilitis, also known as angular stomatitis, involves painful dry fissures on one or both corners of the mouth where the upper and lower lips meet. It’s typically caused by a buildup of saliva that harbors bacteria. Other causes may include systemic conditions like inflammatory bowel disease (e.g., Crohn's disease) or vitamin deficiencies (e.g., pernicious anemia, which is when vitamin B12 can’t be properly absorbed in the GI tract). 

Stomatitis is an inflammation of the oral mucosa, also known as the mucous membrane lining or “skin” inside of the mouth, including cheeks and lips. It presents as painful sores and lesions affecting a patient’s ability to chew or swallow. Possible causes of stomatitis include infection with the herpes simplex virus(HSV)-1, known as the virus responsible for “cold sores”; poor oral hygiene; contact with irritants, such as spicy food; or certain systemic conditions like Behçet disease

Both angular cheilitis and stomatitis are typically diagnosed clinically using a history and physical examination. Some common triggers include atopic dermatitis or eczema, ill-fitting dentures, drooling during sleep, fungal or yeast infections such as thrush, misaligned teeth, malnutrition, Celiac disease, stress, skin allergies, sucking on a thumb or a pacifier, or wearing a face mask. Laboratory tests or diagnostic interventions may be used if the diagnosis is unclear or an underlying condition is suspected. Treatment for both conditions depends on the severity of the condition and the underlying cause. 

Illustration of a person holding their arms over their midsection, clearly uncomfortable and in pain.


Next is gastritis, also known as inflammation of the stomach lining. Gastritis can be acute, lasting less than four weeks, or chronic, lasting more than four weeks. Inflammation can be caused by anything that affects the integrity of the protective barrier lining the stomach. Risk factors include the use of certain medications such as non-steroidal anti-inflammatory drugs (NSAIDs) including ibuprofen, naproxen, diclofenac, celecoxib, mefenamic acid, etoricoxib, indomethacin, Helicobacter pylori infection, stress, and excessive intake of alcohol, caffeine, or spicy foods. 

Signs and symptoms of gastritis include a dull, gnawing pain in the epigastric area (upper central region of the abdomen), nausea, vomiting, and fullness. If left untreated, gastritis can lead to peptic ulcer disease (PUD), which occurs when longstanding or untreated inflammation of the stomach lining causes ulcers to develop. Gastritis is typically diagnosed through taking a history and a physical examination. In cases where the diagnosis is unclear, blood tests and an upper endoscopy with biopsy may be done to confirm it. 

Treatment for gastritis focuses on resolving the underlying cause of inflammation, which may involve lifestyle changes like stopping the use of any offending medications, managing stress, and limiting or omitting caffeine, alcohol, and spicy foods. Medications like (PPIs) (e.g., pantoprazole) may be prescribed to decrease stomach acid production, or antacids (e.g., calcium carbonate) to neutralize stomach acid and allow the stomach lining to heal. Treatment typically includes a combination of PPIs and antibiotics if the underlying cause is an H. pylori infection. 

An illustrated list related to the background, symptoms, causes, and treatments of Melena, AKA black, tarry stool.

Melena and Hematochezia

Blood in the stool can occur due to a variety of conditions affecting any part of the GI tract. Melena and hematochezia both indicate the presence of blood in the stool. More specifically, melena involves thick, dark black, tarry stool that contains partially digested blood, whereas hematochezia involves bright red blood mixed in with stool or coming directly from the anus. 

Typically, melena is caused by bleeding in the upper GI tract, like the esophagus or stomach, leading to partially digested, dark blood. Ulcers, esophageal or gastric varices, Mallory-Weiss tears, gastritis, esophagitis, or malignancy can lead to upper GI bleeding. Whereas hematochezia is typically caused by bleeding in the lower GI tract, like the anus or rectum, and is likely due to conditions like inflammatory bowel disease (e.g., Crohn's disease), anal fissures, hemorrhoids, proctitis, or malignancy.

Diagnosis of melena and hematochezia depends on the type and severity of bleeding and can include blood work (e.g., complete blood count, complete metabolic panel) and an upper endoscopy or colonoscopy, with treatment dependent upon the underlying cause. 

Explore other common conditions:

A Quick Reference Guide to Common Conditions in Older Adults
A Quick Reference Guide to Common Conditions Associated With Pregnancy

About the Author

Kelsey LaFayette, DNP, ARNP, FNP-C, obtained a Bachelor of Arts in Nursing degree from Luther College in 2011. As an RN, she has a clinical background in medical and pulmonary inpatient units, urgent care, and critical care, and obtained her Doctor of Nursing Practice degree at the University of Illinois at Chicago in 2022. Throughout her career, Kelsey has had many opportunities to function in an education role by being a charge nurse, preceptor to new RNs and nursing students, as well as a Clinical Team Lead in charge of creating orientation programs and policies. Through these opportunities, Kelsey realized her ideal career path should focus on the education of nurses, nursing students, patients, families, and anyone else with a desire to learn. Kelsey serves as a manager on the Nursing Content team and has been able to work on various projects that fulfill her love of perpetual learning.


Józia C. McGowan, DO, FACOI, FNAOME, CS, Osmosis from Elsevier Faculty Reviewer


  • Banaszak M, Górna I, Woźniak D, Przysławski J, Drzymała-Czyż S. Association between Gut Dysbiosis and the Occurrence of SIBO, LIBO, SIFO and IMO. Microorganisms. 2023;11(3):573. Published 2023 Feb 24. doi:10.3390/microorganisms11030573

  • Belizário JE, Faintuch J. Microbiome and gut dysbiosis. Exp Suppl. 2018;109:459-476. doi:10.1007/978-3-319-74932-7_13

  • Bijelić B, Matić IZ, Besu I, et al. Celiac disease-specific and inflammatory bowel disease-related antibodies in patients with recurrent aphthous stomatitis. Immunobiology. 2019;224(1):75-79. doi:10.1016/j.imbio.2018.10.006

  • Del Moral-Hernández O, Castañón-Sánchez CA, Reyes-Navarrete S, et al. Multiple infections by EBV, HCMV and Helicobacter pylori are highly frequent in patients with chronic gastritis and gastric cancer from Southwest Mexico: an observational study. Medicine (Baltimore). 2019;98(3):e14124. doi:10.1097/MD.0000000000014124

  • Ghassemi KA, Jensen DM. Lower GI bleeding: epidemiology and management. Curr Gastroenterol Rep. 2013;15(7):333. doi:10.1007/s11894-013-0333-5

  • Hills RD Jr, Pontefract BA, Mishcon HR, Black CA, Sutton SC, Theberge CR. Gut microbiome: profound implications for diet and disease. Nutrients. 2019;11(7):1613. Published 2019 Jul 16. doi:10.3390/nu11071613

  • Rana SV, Malik A. Hydrogen breath tests in gastrointestinal diseases. Indian J Clin Biochem. 2014;29(4):398-405. doi:10.1007/s12291-014-0426-4

  • Rodriguez-Castro KI, Franceschi M, Miraglia C, et al. Autoimmune diseases in autoimmune atrophic gastritis. Acta Biomed. 2018;89(8-S):100-103. Published 2018 Dec 17. doi:10.23750/abm.v89i8-S.7919

  • Oza N, Doshi JJ. Angular cheilitis: a clinical and microbial study. Indian J Dent Res. 2017;28(6):661-665. doi:10.4103/ijdr.IJDR_668_16

  • Wuerth BA, Rockey DC. Changing epidemiology of upper gastrointestinal hemorrhage in the last decade: a nationwide analysis. Dig Dis Sci. 2018;63(5):1286-1293. doi:10.1007/s10620-017-4882-6