An inflamed gallbladder, known medically as cholecystitis, is caused by a gallstone blocking the duct that drains bile in about 90% of cases. The remaining 10% occur without stones, typically in people who are already critically ill. Understanding what triggers the inflammation helps explain why symptoms develop and what to expect from treatment.
How Gallstones Cause Inflammation
Your gallbladder is a small, pear-shaped organ that stores bile, a digestive fluid made by your liver. Bile flows out through a narrow tube called the cystic duct. When a gallstone gets lodged in that duct, bile has nowhere to go. The gallbladder swells as pressure builds, and that swelling compresses the tiny blood vessels in the gallbladder wall. Without adequate blood flow and drainage, the tissue starts to break down. This is what produces the intense, sustained pain in the upper right abdomen that distinguishes an inflamed gallbladder from a simple gallstone attack.
A typical gallstone attack (biliary colic) happens when a stone temporarily blocks the duct, causing cramping pain that fades within a few hours as the stone shifts. Cholecystitis is what happens when the stone doesn’t move. The pain is constant rather than wave-like, often lasting more than six hours, and it frequently comes with fever, nausea, and tenderness so sharp that pressing on the right side of your abdomen while breathing in causes you to catch your breath.
Inflammation Without Gallstones
About 10% of cholecystitis cases develop without any stones at all. This form, called acalculous cholecystitis, tends to strike people who are already seriously unwell: patients in intensive care, people recovering from major surgery or trauma, and those with severe infections or heart failure. The underlying problem is different from stone-related inflammation but the end result is similar.
In these cases, the gallbladder stops contracting normally. Bile sits stagnant inside it, growing thicker and more concentrated, especially when a person is dehydrated, feverish, or hasn’t eaten for an extended period (since eating is what signals the gallbladder to squeeze). At the same time, reduced blood flow to the gallbladder wall, caused by low blood pressure, heart failure, or the body’s inflammatory response during sepsis, damages the tissue directly. This combination of stagnant bile and poor blood supply injures the inner lining of the gallbladder and can allow gut bacteria to invade, worsening the inflammation.
People with diabetes and those receiving nutrition entirely through an IV line are also at higher risk for this stone-free form, because both conditions reduce the gallbladder’s ability to contract and empty on schedule.
The Role of Bacterial Infection
Bacterial infection is often a secondary complication rather than the initial cause. Once the gallbladder wall is damaged by pressure or poor blood flow, bacteria from the intestines can migrate in and multiply in the trapped bile. These infections tend to involve multiple types of bacteria at once. The most common culprits are gut-dwelling organisms like E. coli, Klebsiella, and Enterococcus. In hospital-acquired cases, Pseudomonas species show up more frequently. Anaerobic bacteria, the kind that thrive without oxygen, including Clostridium and Bacteroides species, can also be involved.
When infection sets in, it raises the stakes. An infected, inflamed gallbladder can progress to gangrene (tissue death) or perforation if not treated promptly. This is why fever alongside gallbladder pain is a red flag that warrants urgent evaluation.
Risk Factors That Set the Stage
Since gallstones cause the vast majority of cases, the risk factors for cholecystitis largely overlap with the risk factors for developing gallstones in the first place. The classic teaching mentions the “four Fs” (female, forty, fertile, fat), but the picture is more nuanced than that.
Metabolic syndrome, the cluster of conditions that includes abdominal obesity, high blood sugar, high triglycerides, and low HDL cholesterol, significantly raises your odds. A large cross-sectional study found that having metabolic syndrome increased the likelihood of gallstone disease by 47%. The more components of metabolic syndrome a person has, the higher the risk: gallstone prevalence ranged from 0.56% in people with no metabolic risk factors to 3.60% in those with all of them. Among individual factors, higher BMI, greater waist circumference, and low HDL cholesterol showed the strongest associations.
Rapid weight loss is another well-established trigger. When you lose weight quickly, whether through very low-calorie dieting or bariatric surgery, the liver dumps extra cholesterol into bile, and the gallbladder empties less frequently. Both changes promote stone formation. Pregnancy creates similar conditions: higher estrogen levels increase cholesterol in bile, and progesterone slows gallbladder emptying. Certain medications, particularly hormone replacement therapy and some cholesterol-lowering drugs, can also shift bile chemistry toward stone formation.
What Happens During Treatment
The standard treatment for an inflamed gallbladder is surgical removal, typically done laparoscopically through several small incisions. Current evidence supports performing surgery within 72 hours of symptom onset rather than waiting weeks for inflammation to cool down. Early surgery is associated with shorter hospital stays, lower costs, and fewer readmissions compared to a delayed approach.
Before surgery, you’ll receive IV fluids, pain management, and often antibiotics if infection is suspected. Most people go home within a day or two of laparoscopic surgery and return to normal activities within one to two weeks. Your body adjusts to life without a gallbladder by routing bile directly from the liver to the small intestine. Some people notice looser stools for the first few weeks, but this usually resolves as the digestive system adapts.
For people who are too ill for surgery, particularly those with acalculous cholecystitis in the ICU, a temporary drain can be placed through the skin into the gallbladder to relieve pressure until the patient is stable enough for a more definitive procedure.
Chronic Gallbladder Inflammation
Not all gallbladder inflammation is sudden and severe. Chronic cholecystitis develops from repeated episodes of mild inflammation, usually caused by gallstones that intermittently obstruct the duct and then shift back. Over time, the gallbladder wall thickens and scars, and the organ gradually loses its ability to store and release bile effectively. Symptoms tend to be subtler than acute cholecystitis: recurring discomfort after fatty meals, bloating, and vague upper abdominal pain that comes and goes over months or years. The treatment is the same, surgical removal, but the urgency is lower and the procedure is typically scheduled electively.