A fishy odor to stools is often a sign of underlying gastrointestinal issues that require medical attention. Here are some quick answers about what may cause stools to smell fishy:
Common Causes
Some common causes of fishy smelling stool include:
- Malabsorption disorders like celiac disease or crohn’s disease
- Pancreatitis
- Gallbladder disease
- Giardia infection
- Chronic pancreatitis
- Cystic fibrosis
- Tropical sprue
- Rotavirus
Less Common Causes
While less common, the following conditions may also cause stools to have a fishy odor:
- Proctitis
- Enteritis
- Diverticulitis
- IBS
- Food intolerances like lactose intolerance
- Antibiotic use
- Anal fissures
When to See a Doctor
It’s important to consult a doctor if you notice your stools start to smell fishy. While it may be caused by a relatively harmless stomach bug, it can also signal more serious gastrointestinal issues that require treatment. You should make an appointment with your doctor if you notice:
- Persistent fishy odor lasting more than 3 days
- The fishy smell is accompanied by bloody stool, diarrhea, vomiting, fever or severe pain
- You have other symptoms like unexplained weight loss or severe cramping
Don’t try to self-diagnose the cause of fishy smelling stools. Let your doctor evaluate your symptoms and order any tests needed to pinpoint the underlying problem.
What Causes the Fishy Smell?
There are a few reasons why stools can start to smell fishy. Here are some of the mechanisms behind that unpleasant fishy odor:
Malabsorption Disorders
Malabsorption disorders like celiac disease prevent your small intestine from properly absorbing nutrients from food. This leads to excess fat in the stool, giving it a foul, fishy smell.
Infection
Certain bacterial infections produce byproducts that have a fishy odor. Giardia and e. coli infections can cause this fishy smell.
Inflammation
Inflammatory conditions like inflammatory bowel disease (IBD) cause inflammation in the gastrointestinal tract that changes the composition of the stool, leading to a fishy smell.
Medications
Some medications like antibiotics alter the balance of good and bad bacteria in the gut, leading to a fishy odor.
Underlying Health Conditions
Medical conditions that affect digestion and absorption like cystic fibrosis, chronic pancreatitis, and liver disease can cause stool to smell fishy.
Treatments for Fishy Smelling Stool
Treatment focuses on addressing the underlying cause of the fishy odor. Your doctor will perform tests and exams to diagnose the problem. Treatment options may include:
- Medications: Antibiotics to treat infections or anti-inflammatories to reduce inflammation.
- Diet changes: A gluten-free diet if celiac disease is the cause. Or avoiding foods that worsen symptoms.
- Supplements: Probiotics and digestive enzymes to improve digestion.
- Surgery: Removal of severely damaged sections of intestine or gallbladder if necessary.
The fishy smell should go away once the underlying problem is properly treated. Talk to your doctor to come up with a tailored treatment plan.
When to Seek Emergency Care
If the fishy odor is accompanied by symptoms like severe abdominal pain, uncontrolled vomiting, bleeding, fever over 101 F (38.3 C), or fainting, you need emergency medical care. Call 911 or go to the nearest ER right away. Severe symptoms can signal problems like:
- Intestinal blockage
- Perforated ulcer
- Appendicitis
- Gallbladder inflammation
- Bowel infection
These require rapid diagnosis and treatment to prevent serious and potentially life-threatening complications.
How is the Cause of Fishy Smell Diagnosed?
To figure out why your stools smell fishy, your doctor will typically carry out the following diagnostic steps:
- Medical history – Discuss your symptoms, diet, medications, travel, and risk factors.
- Physical exam – Check for signs of infection, inflammation, or abdominal tenderness.
- Stool sample – Check for blood, excess fat, or pathogens.
- Blood tests – Assess for anemia, infection, liver issues, or malnutrition.
- Imaging – X-rays, CT scan, or endoscopy to visualize the GI tract.
- Biopsy – Takes a small sample to test for celiac disease or IBD.
Your doctor will tailor diagnostic tests based on your symptoms and history. Identifying the underlying cause is key to getting proper treatment.
Prevention
It’s not always possible to prevent stool from smelling fishy, but the following healthy habits can help:
- Drink plenty of fluids to stay hydrated.
- Eat more fiber to promote regular bowel movements.
- Take probiotics to support healthy gut bacteria.
- Limit fatty, spicy, or processed foods that are hard to digest.
- Manage chronic health conditions like diabetes that affect digestion.
- Get regular colonoscopies starting at age 45.
See your doctor at the first sign of persistent fishy odor accompanied by concerning symptoms. Prompt treatment can help resolve the underlying problem and prevent complications.
Conclusion
A fishy smell from stools is never normal and warrants medical attention. It is most commonly caused by malabsorption disorders, infections, medication side effects, inflammation, or chronic health conditions. See a doctor for an accurate diagnosis if the fishy odor persists. With proper treatment of the underlying cause, the unpleasant odor should resolve.