Kidney stones are usually formed following a build-up of certain chemicals in the body.

Certain medical conditions can lead to an unusually high level of these chemicals in your pee.

You're also more likely to develop kidney stones if you do not drink enough water and other fluids.

Kidney stones come in a variety of sizes, shapes and colours. Some are like grains of sand, while in rare cases others can grow to the size of a golf ball.

The main types of kidney stones are:

• calcium stones, the most common type of stone
• struvite stones, usually caused by an infection, like a urine infection
• uric acid stones, usually caused by a large amount of acid in your urine

People who keep getting kidney stones include those who:

• eat a high-protein, low-fibre diet
• are inactive or bed-bound
• have a family history of kidney stones
• have had several kidney or urinary infections
• have had a kidney stone before, particularly if it was before they were 25 years old

Medicines

Certain medicines may increase your risk of developing recurrent kidney stones.

These include:

• aspirin
• antacids
• diuretics (used to reduce fluid build-up)
• certain antibiotics
• certain antiretroviral medicines (used to treat HIV)
• certain anti-epileptic medicines