A fishy smell coming from your belly button is almost always caused by bacteria breaking down trapped sweat, dead skin, and oils in the warm, dark folds of your navel. The belly button is one of the most overlooked spots on the body when it comes to hygiene, and its shape makes it a perfect breeding ground for odor-producing microbes. In most cases, the fix is simple. But certain infections, cysts, and rare conditions can also produce that distinctive fishy scent.
Bacteria Thriving in a Warm, Damp Space
Your belly button, especially if it’s an “innie,” creates a small pocket where moisture, sweat, dead skin cells, and lint collect throughout the day. Bacteria naturally present on your skin feed on this debris, and their metabolic byproducts are what you’re actually smelling. The deeper or more folded your navel is, the more material accumulates and the stronger the odor can get. A fishy smell in particular tends to come from certain types of bacteria that produce nitrogen-rich waste compounds as they break down organic matter.
This is the most common explanation by far. If the smell goes away after a thorough cleaning and there’s no pain, redness, or discharge, bacteria feeding on trapped gunk is almost certainly the cause.
Bacterial or Fungal Infection
When bacteria multiply beyond what’s normal, you can develop an actual infection in the navel. This typically happens when moisture stays trapped for long periods, giving bacteria an ideal environment to overgrow. Signs include redness or discoloration of the surrounding skin, swelling, tenderness, and discharge that may be yellow, green, or cloudy. The discharge itself often has a strong, unpleasant smell.
Yeast infections caused by Candida can also develop in the belly button, though they don’t usually produce a fishy smell specifically. If a yeast overgrowth occurs alongside a skin condition called intertrigo (where skin folds rub together and trap moisture), you may notice a musty odor rather than a fishy one. The distinction matters: bacterial infections tend to produce sharper, fishier smells, while fungal infections lean more toward a stale or musty scent.
Cysts and Trapped Debris
Sometimes a small cyst forms in or near the belly button. Epidermal inclusion cysts (sometimes called sebaceous cysts) fill with a thick mixture of keratin and cellular debris. If one of these cysts ruptures or is squeezed, the substance that drains out is thick, yellowish, and noticeably foul-smelling. A ruptured cyst can also cause swelling, pain, and skin discoloration around the navel.
Another possibility is an omphalolith, essentially a stone-like ball of compacted dead skin, oil, and dirt that forms over months or years inside a deep belly button. These are uncommon but can produce a strong odor when disturbed or dislodged. If you notice a hard, dark mass inside your navel, that’s likely what it is.
Urachal Abnormalities
Before birth, a tube called the urachus connects the bladder to the umbilical cord. It normally closes completely, but in some people it doesn’t seal all the way. A urachal sinus leaves a small blind-ending tract from the belly button inward, and a urachal cyst can form along this pathway. These abnormalities sometimes go undetected for years until they become infected.
When a urachal cyst gets infected, it can leak cloudy or bloody fluid from the belly button and cause abdominal pain and redness around the navel. The drainage often has an unpleasant odor. Diagnosis usually starts with an ultrasound, and in some cases a contrast dye test is used to map the tract. This is a less common cause, but worth considering if you have persistent discharge that keeps coming back despite good hygiene.
Infected Belly Button Piercings
If you have a navel piercing, some tenderness, redness, and crusting is normal for up to 12 to 18 months as it heals. But smelly discharge is not part of normal healing. Discharge from an infected piercing can be yellow, green, gray, brown, white, or bloody, and if it has an odor, that strongly suggests infection rather than typical healing. Other warning signs include painful swelling, warmth around the piercing site, increased redness, and feeling generally unwell with fever or chills.
A Rare Metabolic Cause
There is a genetic condition called trimethylaminuria that causes the body to produce a persistent fishy odor. People with this condition can’t properly break down a compound found in certain foods (eggs, fish, beans, and organ meats, among others). The unprocessed compound builds up and gets released through sweat, urine, and breath. Because the belly button traps sweat, it can concentrate the smell in that area, though the odor wouldn’t be limited to just the navel. If you notice a fishy smell from multiple parts of your body, not just your belly button, this is worth looking into.
How to Clean Your Belly Button Properly
Most fishy belly button odors resolve completely with consistent cleaning. The recommended approach is simple: use a mild, fragrance-free soap and warm water. For an innie, lather soapy water onto a cotton swab or the corner of a washcloth, then gently work it around the inside of the navel to remove dirt and debris. Don’t scrub aggressively. When you’re done, use a clean, dry cotton swab or towel corner to dry the inside thoroughly. Moisture left behind is what invites bacteria back.
For an outie, lather with mild soap using your hands or a washcloth, rinse, and dry completely. Either way, aim to clean your belly button at least once a week, though daily cleaning during showers is even better if you’re prone to odor. Avoid putting scented body lotions inside your navel, as these can feed bacteria and irritate the skin.
Signs That Point to Something More Serious
A smell that goes away with regular cleaning is nothing to worry about. But certain symptoms suggest you’re dealing with more than just poor hygiene. Watch for discharge that’s yellow, green, or bloody, especially if it keeps returning. Redness, swelling, or skin that feels hard or thick around the navel is another flag. Pain or tenderness when you touch the area, particularly if it’s getting worse over time, warrants attention. Fever alongside any of these symptoms is the clearest signal that an infection needs treatment.
Persistent drainage that returns no matter how well you clean could point to a urachal abnormality or a cyst that needs to be evaluated with imaging. And if the fishy smell is present in your sweat, breath, or urine beyond just the belly button, that pattern is worth discussing with a doctor to rule out trimethylaminuria.