Healthy urine should be clear and straw-coloured, and shouldn't be particularly smelly.
Some people find that their urine smells stronger and is darker first thing in the morning when it's more concentrated, or generally when they're dehydrated.
Also, certain food and drinks, including asparagus, beer, garlic and coffee, may temporarily give urine a stronger smell.
Certain medicines and vitamin and mineral supplements can also alter the odour of urine – but never stop taking any medication without speaking to your GP first.
You may find the smell of your urine improves by drinking more fluids. Generally, make sure you drink enough fluid so you're not thirsty for long periods, and steadily increase your fluid intake when exercising and during hot weather.
Do I ever need to see my GP?
It's not necessary to see your GP about smelly urine unless you're concerned – for example, if you have other symptoms too.
See your GP if:
You have symptoms of a urinary tract infection (UTI), such as pain or a burning sensation when urinating and a need to urinate often. This is the most likely cause of unexplained foul-smelling urine. A UTI will often get better on its own, especially if you increase your fluid intake. It is less likely to get better without treatment in men than in women.
You have diabetes and feel you're not managing it properly – urine can smell abnormally sweet in uncontrolled diabetes.
Could it indicate any other medical condition?
The following conditions can sometimes cause smelly urine, but they are uncommon:
urinary stones – these may cause an ammonia-like odour (read about bladder stones and kidney stones)
a bladder fistula – this is an abnormal connection between your intestines and bladder
maple syrup urine disease – this rare genetic disease means you have difficulty breaking down certain amino acids (read information on maple syrup urine disease, which links to an external site)
liver failure (read about the different types of liver disease that can lead to liver failure)
diabetic ketoacidosis – this dangerous complication of diabetes happens when the body is unable to use blood glucose because there isn't enough insulin, so it breaks down fat as an alternative source of fuel, causing a build-up of a by-product called ketones