Common Causes (Ranked by Likelihood)
The belly button — especially deep 'innie' navels — collects dead skin cells, sweat, sebum, and lint that most people never fully clean. Gram-negative bacteria (which include species like Proteus, Pseudomonas, and E. coli) metabolize this organic debris and produce trimethylamine and other amines that smell strongly of fish. A 2012 study from North Carolina State University found an average of 67 bacterial species per belly button, with high variation between individuals. The warm, moist, airless environment is ideal for bacterial proliferation.
Candida yeast thrives in the same warm, moist conditions as bacteria, and navel yeast infections are relatively common — particularly in people who are overweight, have deep navels, sweat heavily, or have recently taken antibiotics. Yeast infections in the belly button produce a yeasty, bread-like, or sometimes fishy/cheesy smell alongside a whitish or yellowish discharge and often mild itching or redness. The skin may appear red and slightly raw at the navel opening.
The urachus is a tube that connects the bladder to the belly button in fetal development and normally closes at birth. If it doesn't close completely, a urachal cyst can form — and if it gets infected, it produces drainage from the navel that may smell fishy or foul and contain pus or clear fluid. This is uncommon but important to rule out if the belly button produces ongoing fluid discharge that doesn't resolve with cleaning.
Navel piercings create a wound channel that can harbor bacteria, particularly Staphylococcus aureus, Pseudomonas, and mixed organisms. An infected piercing produces pus, redness, and a range of odors including fishy (from Gram-negative bacteria), cheesy, or generally foul. Even healed piercings can flare with infection if jewelry is changed, irritated, or contaminated. The fishy smell from a piercing infection is more localized to the jewelry area.
How to Fix It
Proper Belly Button Cleaning Technique
$0-5Most fishy belly button smell resolves with consistent, thorough cleaning.
- 1Apply a small amount of antibacterial soap (or diluted castile soap) to a cotton swab or Q-tip.
- 2Gently insert the swab into the navel and clean the inner walls, reaching as deep as the navel pocket allows.
- 3Rinse with warm water using the swab — rinse thoroughly to remove soap residue, which can itself cause irritation.
- 4Pat completely dry with a clean cloth or use a cotton swab to absorb moisture. Moisture left in the navel restores the bacterial environment.
- 5Do this daily during showering. Most people never actively clean their belly button — passive soap runoff is insufficient for deep navels.
Treat Yeast Infection in Navel
$8-20If there's white discharge, itching, or redness alongside the fishy smell.
- 1Apply an OTC antifungal cream (clotrimazole 1% or miconazole 2%) to the inside of the navel twice daily for 1-2 weeks.
- 2Keep the area dry — moisture is what yeast needs to thrive. Pat dry after showering; consider using a small piece of gauze to absorb excess moisture.
- 3If overweight and the navel fold traps moisture throughout the day, consider applying a small strip of gauze or a folded tissue to absorb moisture between cleanings.
- 4The redness and smell should improve within 3-5 days; continue treatment for the full course.
- 5If no improvement after 2 weeks, see a doctor — prescription antifungals or a bacterial culture may be needed.
Address Piercing Infection
$0-50For navel piercings with signs of infection.
- 1Clean the piercing twice daily with sterile saline solution (not hydrogen peroxide or alcohol — these damage healing tissue).
- 2Do not remove the jewelry from an infected piercing — this can trap the infection. Keep it in until the infection is resolved.
- 3Mild infections (redness, small amount of discharge) often resolve with saline cleaning alone over 1-2 weeks.
- 4For pus-producing, swollen, or spreading infections, see a doctor — oral antibiotics may be needed.
- 5If the infection recurs or the piercing doesn't heal after 6-9 months, the jewelry material may be causing a reaction (switch to implant-grade titanium or solid 14k gold).
When to Call a Professional
Persistent liquid discharge from the navel not related to a piercing — possible urachal cyst; see a doctor.
Redness spreading beyond the navel area with warmth, swelling, and fever — possible cellulitis requiring antibiotics urgently.
Discharge that is bloody, brown, or contains visible pus — warrants medical evaluation.
Smell that persists despite consistent daily cleaning for 2-3 weeks — see a dermatologist or doctor to rule out fungal infection or structural issue.
How to Prevent It
Clean inside the navel daily with a cotton swab during showering — don't rely on passive soap runoff.
Dry the navel completely after showering — residual moisture is the primary driver of bacterial and yeast growth.
Avoid applying lotions or creams inside the navel — these add moisture and organic substrate for bacteria.
Wear breathable, natural-fiber clothing that reduces navel area sweating.
For piercings, maintain consistent saline cleaning especially during the healing period (6-12 months for navel piercings).
Why Innie Belly Buttons Smell More Than Outies
The depth and shape of a belly button determines how much organic material accumulates and how much air circulates. Deep 'innie' navels create a pocket that traps dead skin cells, sweat, sebum, and lint while limiting airflow — the combination that bacteria and yeast need. Shallow or 'outie' belly buttons expose the navel tissue to more air, which keeps conditions drier and less favorable for microbial growth.
The bacteria most responsible for the fishy smell in belly buttons belong to Gram-negative species that produce trimethylamine as a metabolic byproduct. These same bacteria live on skin throughout the body, but the navel's enclosed environment concentrates their products. In a 2012 belly button microbiome study, researchers found that while the average person harbored about 67 species in their navel, some individuals had unique combinations — including one person who had a bacterium previously only found in soil in Japanese cherry blossom gardens.
Frequently Asked Questions
Standard showering with soap running over the body doesn't clean inside the navel — it requires active cleaning with a cotton swab or finger. The navel pocket traps debris in areas that water and soap don't reach passively. If you clean it thoroughly and the smell returns within a day, bacterial colonization is well established and may require consistent daily cleaning for 1-2 weeks to fully resolve.
Not necessarily — a smelly belly button is most often just normal bacterial activity in an undertreaned area. Signs that suggest actual infection include: visible pus or thick discharge, redness and swelling around the navel, warmth, tenderness, or fever. A fishy smell without these signs is usually just bacterial overgrowth from debris accumulation, not an active infection.
The fishy smell specifically indicates Gram-negative bacteria producing trimethylamine — the compound responsible for the smell of rotting fish. Belly buttons can also smell yeasty (Candida), cheesy (Brevibacterium), or generally musty depending on which microorganisms dominate. The fishy variant is caused by the same bacterial chemistry that produces fishy body odor elsewhere.
Indirectly — sulfur-rich foods (garlic, onions, cruciferous vegetables) are excreted in sweat, including the tiny amount of sweat produced in navel skin. This provides additional substrate for bacteria in the navel. The effect is small compared to hygiene factors, but consistent high-sulfur diets combined with poor navel cleaning can worsen the smell.