Pain in the upper right part of your belly that starts after a big or fatty meal and lasts for hours is a classic sign of a gallbladder attack. When fat and protein from a meal reach the small intestine, they trigger the release of cholecystokinin (CCK), a peptide hormone that tells the gallbladder to squeeze bile into the gut. If a gallstone is blocking the way out, that squeeze can hurt. Pain lasting several hours, fever or chills, or yellowing of the skin or eyes means you should get care right away.
The meal signal: cholecystokinin
A 2021 review in Frontiers in Endocrinology describes CCK as a peptide hormone made by cells scattered through the upper two-thirds of the small intestine, with fats and protein in a meal as the main triggers for its release. Gallbladder contraction was the first effect scientists recognized, which is how the hormone got its name. CCK also prompts the pancreas to release digestive enzymes and slows how quickly the stomach empties, so bile and enzymes arrive in step with the food that needs them.
The UniProt record for cholecystokinin lists the same jobs, gallbladder contraction and pancreatic enzyme release, and shows that the hormone circulates in several lengths cut from one precursor, from 58 amino acids down to 8.
Why a gallstone turns that signal into pain
The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) explains that when gallstones block the bile ducts, bile builds up in the gallbladder and causes an attack, sometimes called biliary colic. The pain is usually in the upper right abdomen and can last several hours. NIDDK notes that attacks often follow heavy meals and usually happen in the evening or during the night, and that after one attack, more are likely. They often stop when the stone shifts and stops blocking the duct.
MedlinePlus describes the pain as lasting at least 30 minutes in the right upper or middle upper abdomen, constant or cramping, sharp or dull. Gallstones are more common in women, Native American and Hispanic people, people over 40, people who are overweight and those with a family history. Some people have gallstones that cause no symptoms at all; NIDDK says these “silent” stones do not need treatment.
If you notice the pattern, write it down: what you ate, when the pain started, where it was and how long it lasted. That record is useful to a clinician, because NIDDK cautions that gallstone pain can resemble appendicitis, ulcers, pancreatitis and acid reflux, all of which need a doctor’s attention.
Signs that need care right away
NIDDK says to see a doctor right away if, during or after an attack, you have:
- Abdominal pain lasting several hours.
- Nausea and vomiting.
- Fever, even a low one, or chills.
- Yellowing of the skin or the whites of the eyes (jaundice).
- Tea-colored urine and light-colored stools.
These can signal a serious infection or inflammation of the gallbladder, liver or pancreas.
How the same signal shows up in testing
NIDDK’s diagnosis page calls ultrasound the best imaging test for finding gallstones. When the question is how well the gallbladder empties, doctors may order a HIDA scan, also called cholescintigraphy. A tracer goes into a vein and a camera follows it through the liver and gallbladder; NIDDK says a substance that makes the gallbladder squeeze may also be given. MedlinePlus explains this can be a medicine in the vein or a rich nutrition drink, and that you will be asked to stop eating and drinking four hours before the test.
That medicine is typically a synthetic CCK analog. A 2024 paper in the Journal of Nuclear Medicine Technology reports that recurring shortages of synthetic CCK pushed some centers to use a fatty-meal drink instead, with comparable diagnostic accuracy in similar patients. If your instructions mention a drink or an IV medicine partway through the scan, both are doing what a meal’s CCK signal does naturally.
By The Everyday Brief · AI-assisted editorial. Drafted with AI research assistance; claims checked against the linked sources (fetched 2026-10-05 PT). Not medical advice.
Sources
- NIDDK: Symptoms & Causes of Gallstones
- NIDDK: Diagnosis of Gallstones
- MedlinePlus (U.S. National Library of Medicine): Gallstones
- MedlinePlus: Gallbladder radionuclide scan
- Miller LJ, Harikumar KG, Wootten D, Sexton PM. Roles of Cholecystokinin in the Nutritional Continuum. Physiology and Potential Therapeutics. Frontiers in Endocrinology, 2021.
- Peacock JG, Hayes HA, Connor TD. Use of a Fatty Meal Cholecystagogue Protocol in Hepatobiliary Scintigraphy for Chronic Functional Gallbladder Disease. Journal of Nuclear Medicine Technology, 2024.
- UniProt: P06307, Cholecystokinin (human)