Small Intestinal Fungal Overgrowth

Small intestinal fungal overgrowth (SIFO) is the term coined to describe a theoretical condition in which atypical amounts of fungi are present in the small intestine. This overgrowth is thought to result in digestive symptoms.

A woman sitting on her bed with abdominal pain
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Why Fungi May Be Responsible for GI Issues

An overgrowth of fungi, particularly in the form of the yeast Candida, has been noted as a cause of infection in various areas of the body:

  • Oropharyngeal candidiasis (Thrush (mouth/throat))
  • Candida esophagitis (esophagus)
  • Candidemia (bloodstream)
  • Cutaneous candidiasis (skin)
  • Genital or vulvovaginal candidiasis (Vaginal yeast infection)
  • Invasive candidiasis (severe infection)

The fact that a fungal overgrowth can cause symptoms in the body has led some researchers to investigate whether or not an overgrowth in the small intestine might be responsible for unexplainable gastrointestinal symptoms.

It is important to keep in mind that Candida is a normal part of normal gut flora. Its overgrowth is perhaps pathogenic, but its presence is not.

Evidence for SIFO

Very little has been researched or published about the existence of fungal overgrowth in the small intestine. The challenge in identifying a problem such as SIFO is that the role of fungi in the body is poorly understood. Fungi occur naturally in the guts of healthy individuals. At what point the presence of fungi becomes something that causes symptoms is not known at the present time.

As of now, only case reports have been published of individuals who achieved symptom relief of abdominal pain and diarrhea after taking antifungal medication.


According to one report, patients who have SIFO experience symptoms that are quite similar to that of IBS:

  • Abdominal pain
  • Gas and bloating
  • Diarrhea
  • Flatulence

Risk Factors

It is theorized that SIFO is more likely to be seen in people who have:

Others theorized to be at risk are people who are taking antibiotics or steroids, or are undergoing chemotherapy.


SIFO is diagnosed through the taking of a sample of fluid from the small intestine during an endoscopy. The sample is then examined for its fungal content. Although a stool test can identify the presence of Candida, it cannot be used to establish a symptom-causing overgrowth.


There are medications available which are anti-fungal. Again, research into their effectiveness in treating any possible overgrowth is almost non-existent.

The Bottom Line

Any discussion of the role of fungi in the onset or maintenance of unexplained intestinal symptoms, such as those seen in IBS, can only be viewed in the most preliminary of stages. Continued research into the area will be welcomed, particularly if it can be established that addressing a fungal overgrowth does result in symptom relief.

4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Richardson JP, Ho J, Naglik JR. Candida-epithelial interactions. J Fungi (Basel). 2018;4(1). doi:10.3390/jof4010022

  2. Erdogan A, Rao SS. Small intestinal fungal overgrowth. Curr Gastroenterol Rep. 2015;17(4):16. doi:10.1007/s11894-015-0436-2

  3. Rodrigues CF, Rodrigues ME, Henriques M. Candida sp. Infections in Patients with Diabetes Mellitus. J Clin Med. 2019;8(1). doi:10.3390/jcm8010076

  4. Rao SSC, Tan G, Abdulla H, Yu S, Larion S, Leelasinjaroen P. Does colectomy predispose to small intestinal bacterial (SIBO) and fungal overgrowth (SIFO)?. Clin Transl Gastroenterol. 2018;9(4):146. doi:10.1038/s41424-018-0011-x

Additional Reading

By Barbara Bolen, PhD
Barbara Bolen, PhD, is a licensed clinical psychologist and health coach. She has written multiple books focused on living with irritable bowel syndrome.