Gallstones develop because of a chemical imbalance in the bile in the gallbladder. Bile is a liquid. It is produced by the liver to help digestion.
It's unclear what causes this imbalance.
But gallstones can form in the gallbladder if there are high levels of:
- cholesterol
- bilirubin
About 4 in 5 gallstones are made of cholesterol.
Bilirubin is a waste product. About 1 in 5 gallstones is made of bilirubin.
These chemical imbalances cause gallstones to develop in the bile. It can take years for gallstones to form. They can be as small as a grain of sand or as large as a pebble.
Sometimes you will only have 1 stone, but it is more likely you will have a few at the same time.
Who is at risk of getting gallstones
Gallstones are more common if you:
- are female, especially if you have had children, are taking the combined (oestrogen and progesterone) pill, or are having high-dose oestrogen therapy
- have extra weight or obesity
- are age 40 or older - your risk of gallstones increases with age
- have Crohn's disease
- have a close family member who had gallstones
- have recently lost weight - from dieting or weight-loss surgery
- are taking an antibiotic called ceftriaxone
- have a condition that affects the flow of bile
Conditions that affect the flow of bile include:
- cirrhosis (scarring of the liver)
- primary sclerosing cholangitis
- obstetric cholestasis
