How Is Urine Made?

Your urine is made by the kidneys and stored in the bladder. The kidneys act as a filter, draining the water and waste products from the blood and keeping the blood cells and larger protein molecules in the circulation. Most of the water is absorbed back into the blood, leaving the waste substances as a more concentrated solution. The amount of water absorbed depends on how much is in the blood –the kidneys work hard to keep blood at its usual concentration. When you are slightly dehydrated, your urine will be stronger and dark yellow as most of the water is absorbed back into the blood. When you drink an adequate amount of fluids, the urine will be paler as the waste products in urine are more diluted.

Why Is My Urine a Strange Colour?

As urine also contains waste products from the blood, its colour is affected by what else is in the blood, such as foods and chemicals. About 1 in 10 people find their urine turns red after they have eaten beetroot, though most people do not experience this. It seems to be more common in people with anaemia.

Red, brown or smoky-coloured urine can also be caused by taking medication, such as senna, phenolphthalein or the tuberculosis drug rifampicin. However, it may also indicate bleeding into the kidneys or bladder. This is usually due to an infection but can be caused by a tumour. Cystitis usually means you have an infection in the bladder, making you want to pass urine more frequently than usual. There may be a burning or stinging pain as the urine is passed, and there may be a pain at the bottom of the abdomen. With this infection, the urine may be cloudy, if not pink, and often has an unpleasant smell. You should make sure you drink plenty of fluids each day to flush the bacteria from the bladder. Cranberry juice is thought to stop the bacteria sticking to the bladder and help clear up the infection, though this has not been proved. If these symptoms do not go away, however, antibiotics may be needed to clear up the infection.

Red urine. If the infection spreads into the kidneys, you may develop pyelonephritis. This usually causes a pain in your lower back as well as fever, and you may feel sick, with vomiting, diarrhoea and fits of shivering. The urine may be red or pink, and there may be symptoms like those of cystitis. This condition needs to be treated with antibiotics to prevent kidney damage. Drink lots of fluids too. Any change in the colour of your urine that you can’t link to anything you’ve eaten should be checked by your doctor. Blood or red urine may be a sign of kidney or bladder cancer; if this should be the case, please see your health care provider.


First published on:
Reviewed and edited by: Dr Diane Newman
Last updated: October 2020

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