A lump in or around your belly button is most often an umbilical hernia, a condition where tissue pushes through a weak spot in the abdominal wall right behind the navel. Up to 25% of adults have one when checked with ultrasound, and many never realize it. But hernias aren’t the only explanation. Cysts, infections, accumulated debris, and a handful of less common conditions can all produce a noticeable bump in the same spot.
Umbilical Hernia: The Most Likely Cause
Umbilical hernias account for 6% to 14% of all abdominal wall hernias in adults, making them the second most common type after groin hernias. What you feel is usually a soft, squishy bulge at or just beside the navel. It may get more noticeable when you cough, strain on the toilet, or lift something heavy, then flatten when you lie down and relax. Many people live with a small umbilical hernia for years without any pain at all.
Hernias develop when the ring of muscle that once held your umbilical cord doesn’t close completely or weakens over time. Pregnancy, obesity, repeated heavy lifting, and conditions that increase abdominal pressure (like chronic coughing or fluid buildup in the abdomen) all raise the risk. The bulge itself is often a small pad of fat or a loop of intestinal lining poking through the gap.
Cysts and Skin Growths
A firm, round, marble-like lump that sits within the skin rather than behind it is more likely a cyst. Sebaceous cysts (also called epidermoid cysts) form when a pore or hair follicle gets blocked, trapping oily secretions beneath the surface. They’re usually painless and moveable under your fingers. If one becomes infected, it can turn red, warm, and tender, and may start leaking thick, foul-smelling fluid.
Lipomas, which are slow-growing fatty lumps just under the skin, can also appear near the navel. They feel soft and doughy and shift slightly when you press on them. Neither cysts nor lipomas are dangerous on their own, though an infected cyst sometimes needs to be drained.
Belly Button Stones
If the lump looks dark, hard, and almost rock-like, you may be dealing with an omphalolith, sometimes called a belly button stone. These form when dead skin cells, oil, and lint accumulate deep inside the navel over months or years, eventually hardening into a compact mass. They typically appear as a dry, blackish lump with a grayish underside and can reach about 1.5 cm across. People with deep belly buttons who don’t regularly clean the area are most prone. Removal and a good cleaning usually solve the problem entirely.
Infection Around the Navel
Redness, swelling, warmth, and discharge around the belly button point toward an infection. In adults this can happen when bacteria get into a cyst, a piercing site, or a small skin break inside the navel. Signs include tenderness that spreads outward from the center, pus or cloudy fluid, and sometimes a foul smell. A foul-smelling discharge in particular suggests anaerobic bacteria, the type that thrive in low-oxygen environments like a deep, moist belly button.
Infections caught early usually respond well to antibiotics or drainage. Left alone, they can spread into the surrounding skin and deeper tissue.
Umbilical Endometriosis
For people who menstruate, a belly button lump that swells, shrinks, and hurts on a predictable monthly cycle may be umbilical endometriosis. This happens when tissue similar to the uterine lining grows on or near the navel. The nodule often appears dark red, brown, or bluish with a velvety surface. During the days before a period, the tissue becomes congested just like the lining inside the uterus, causing increased pain and swelling. Some people also notice bleeding from the belly button itself during menstruation.
Symptoms can be subtle for years before the pattern becomes obvious. If you notice that the lump consistently worsens in the premenstrual window and improves afterward, that cyclical pattern is the key clue to bring up with your doctor.
How the Lump Gets Diagnosed
A doctor can often tell the difference between a hernia and a superficial cyst just by feeling the area. Hernias have a palpable gap in the abdominal wall muscle, while cysts and other skin-level lumps move freely within the tissue above that muscle layer. If there’s any uncertainty, ultrasound is the usual first step. It’s painless, quick, and good at distinguishing a fluid-filled cyst from a hernia sac from a solid mass. CT or MRI may follow if the ultrasound raises questions about something deeper or more complex.
When a Hernia Needs Surgery
Small, painless umbilical hernias don’t always require treatment. Many doctors take a “watchful waiting” approach for defects under 2 cm, especially if you’re not having symptoms. For gaps larger than 2 to 3 cm, or for anyone with persistent pain, surgical repair becomes the standard recommendation. Surgeons typically close small defects with stitches alone, while larger ones (generally above 5 cm) almost always get reinforced with mesh to reduce the chance of the hernia coming back. Having a BMI over 30 or a defect wider than 2 cm increases the risk of the repair failing, which is one reason doctors may suggest weight management alongside surgery.
Symptoms That Need Urgent Attention
Most belly button lumps are not emergencies, but a hernia that suddenly becomes hard, painful, and impossible to push back in may be incarcerated, meaning tissue is trapped in the gap and can’t slide back into the abdomen. This can progress to strangulation, where blood flow to the trapped tissue gets cut off entirely. Warning signs include severe abdominal pain, nausea or vomiting, a visibly swollen or distended abdomen, and skin over the lump turning red or dark. A strangulated hernia is a surgical emergency because the trapped tissue can die within hours.
Similarly, a firm, irregular lump that feels fixed in place and doesn’t move when you press on it is worth getting checked promptly. In rare cases, a hard nodule at the navel, sometimes called a Sister Mary Joseph nodule, can signal an internal cancer that has spread to the abdominal wall. These nodules range from half a centimeter to several centimeters, may be painful, and sometimes discharge fluid. This is uncommon, but it’s the reason any new, hard, non-moveable lump deserves a medical evaluation rather than a wait-and-see approach.