Kidney infections: symptoms and treatments

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A kidney infection occurs when bacteria migrates from your bladder into one or both of your kidneys. Symptoms can come on quickly, sometimes in a matter of hours, and include pain in the back or side, sickness and feverishness.

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You may feel the need to urinate more frequently, have a need to urinate but only produce a small amount, feel a burning sensation upon urination or feel like you have a full bladder even after you have urinated. In some cases, you may notice pus or blood in the urine.

Although kidney infections don't pose a serious risk to your health, you should make an appointment to see your GP as quickly as possible, as treatment is required to prevent symptoms worsening and to prevent permanent damage to the kidney. Once diagnosed, your doctor will prescribe a course of antibiotics and may also offer you painkillers.

More vulnerable groups, for example those with a pre-existing health condition or women who are pregnant, may be admitted to hospital as a precaution, where antibiotics can be administered by a drip.

If you have pain upon urination you may be suffering from cystitis, a less serious infection of the bladder. Left untreated, cystitis can cause a kidney infection, so it's best to see your doctor.

Cause of kidney infections
The kidneys main function is to filter out waste products from the blood along with excess fluid, which is then passed out of the body as urine.

When bacteria, most commonly E. coli, accidentally gets into the urethra (the tube through which urine passes out of the body) and travels up through the bladder into one of the kidneys, an infection can occur. Usually, only one kidney is affected.

Risk factors
Kidney infections are relatively uncommon. Around 1 in every 830 people suffers with a kidney infection each year, according to NHS Choices.

Although men, women and children can all be affected, women are six times more likely to get them than men. Women are more at risk because their urethra is shorter than a man's, which makes it easier for bacteria to travel to the kidneys.

Sexually active women are also more likely to get them, as having frequent sex increases the risk of picking up an infection. Pregnant women are also slightly more at risk.

Younger children are also vulnerable to developing kidney infections because their small urinary tract makes it easier for bacteria to reach their kidneys. An estimated five per cent of cases of high temperature in children is caused by a kidney infection, according to NHS Choices.

Preventing kidney infections
Keeping your bladder and urethra free from bacteria is the best way to avoid a kidney infection. The main advice is to drink plenty of fluids, preferably water, to help wash bacteria out of your bladder and urinary tract. When you need to urinate go straight away - don't wait if you can help it.

Many people find that drinking cranberry juice can help to prevent cystitis. However, if you're taking warfarin (used to prevent blood clots), cranberry juice is best avoided as it can make the drug more potent and lead to excessive bleeding.

Women are advised to urinate before and after having sex and to wipe from the front to the back after using the toilet and to avoid using genital deodorant sprays and douches.

If you suffer with constipation, treat it promptly, as having constipation can also increase your chances of developing a urinary tract infection. Eating more fibre (20-30g of fibre a day), drinking lots of fluids and taking a mild laxative may help. If symptoms don't improve after a week or so, see your GP.

Finally, take care with contraceptives. If you get frequent urinary tract infections (more than three a year) avoid using spermicide-coated condoms or diaphragms, as these can stimulate the production of bacteria. Lubricated condoms that don't contain spermicide are a better option than unlubricated ones, which can irritate the urethra, making it more vulnerable to infection.