Normal urine color ranges from pale yellow to deep amber — the result of a pigment called urochrome. But urine color isn't always normal.

B vitamins turn urine an eye-popping neon yellow, for instance. Carrot juice can tint it orange. And porphyria, a disease that affects your skin and nervous system, earned its reputation — and its name — by turning urine the color of port wine.

Most changes in urine color are harmless and temporary — the result of certain foods, dyes, supplements or prescription drugs. Occasionally, though, unusual urine color can indicate an infection or serious illness. Talk to your doctor about changes in urine color that persist or don't seem linked to medications or food.

Normal urine color varies, depending on how much water you drink. Fluids dilute the yellow pigments in urine, so the more you drink, the clearer your urine looks. When you drink less, the color becomes more concentrated — severe dehydration can produce urine the color of amber.

But sometimes urine can turn colors far beyond what's normal, including red, blue, green, dark brown and cloudy white. Most color changes are painless and occur without other signs and symptoms. But if the color change is due to a urinary infection, you may have:

• A strong, persistent urge to urinate
• Burning pain with urination
• Frequent urination
• Fever, chills, sweats
• Abdominal pain that comes in waves
• Strong-smelling urine (normal urine should have little or no odor)

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Female urinary system

Urine is made up of excess water and waste products that have been filtered from your blood by your kidneys. Its yellow color comes from urochrome, a pigment that results from the breakdown of hemoglobin, the oxygen-carrying protein in red blood cells.

Discolored urine is often caused by medications, certain foods or food dyes. For instance, the dyes used in some sugary cereals can show up in kids' urine. In some cases, though, changes in urine color may be caused by certain health problems.

Here's a look at possible causes for abnormal urine color:

Red or pink urine
Despite its alarming appearance, red urine isn't necessarily serious. Causes include:

• Blood. The presence of red blood cells is the main reason urine turns red. Usually, bleeding isn't severe and occurs without other signs or symptoms. Factors that can cause urinary blood, known medically as hematuria, range from strenuous exercise, urinary tract infections and an enlarged prostate to kidney or bladder stones, kidney disease, and, occasionally, kidney cancer or bladder cancer.
• Foods. Beets, blackberries and mom's rhubarb pie can turn urine red or pink.
• Medications. Certain laxatives — Ex-lax is an example — can cause red urine. Prescription drugs that have the same effect include antipsychotics such as chlorpromazine (Thorazine) and thioridazine and the anesthetic propofol (Diprivan).
• Toxins. Chronic lead or mercury poisoning can cause urine to turn red. This may be the result of high levels of excreted porphyrins, the same pigments that discolor the urine of people who have porphyria.

Orange urine
Orange urine is hard to miss. Blame it on:

• Foods and supplements. Leading food culprits include vitamin C and carrots and carrot juice. Large amounts of carotene, the orange pigment in carrots, winter squash and other vegetables, can also discolor the palms of your hands and soles of your feet.
• Medications. Medications that can turn urine orange include the antibiotic rifampin; the blood thinner warfarin (Coumadin); phenazopyridine (Pyridium), which treats urinary tract discomfort; some laxatives and certain chemotherapy drugs.
• Dehydration. Drinking too few fluids can concentrate urochrome, making urine much deeper in color.

Blue or green urine
A dye used in several medications that treat urinary pain (Trac Tabs, Urised) can turn urine blue. Other offenders include:

• Foods. Asparagus gives urine a greenish tinge as well as a characteristic odor.
• Medications. A number of medications produce blue urine, including amitriptyline, indomethacin (Indocin), cimetidine (Tagamet), the anti-nausea drug phenergan and several multivitamins.
• Medical conditions. Familial hypercalcemia, a rare inherited disorder that causes high levels of calcium, is sometimes called "blue diaper syndrome" because children with the disorder have blue urine.

Dark brown or tea-colored urine

• Food. Eating large amounts of fava beans, rhubarb or aloe can cause dark brown urine.
• Medications. A number of drugs can darken urine, including the antimalaria drugs chloroquine and primaquine; the antibiotic metronidazole; nitrofurantoin, which treats urinary tract infections; laxatives containing cascara or senna; and methocarbamol, a muscle relaxant.
• Medical conditions. Some liver disorders, especially hepatitis and cirrhosis, and the rare hereditary disease tyrosinemia can turn urine dark brown. So can acute glomerulonephritis, a kidney disease that interferes with the kidney's ability to remove excess fluid and waste.

Cloudy or murky urine
Urinary tract infections and kidney stones can cause urine to appear cloudy or murky.

Eating foods that can discolor urine, such as berries, asparagus and rhubarb, or taking certain medications makes it more likely that you'll have harmless changes in the color of your urine. Whether you react or not depends on the amount of food or medication you take and your own body chemistry.

Factors that put you at risk of medical conditions that can affect urine color include the following:

• Age. Many men older than 50 have occasional urinary blood due to an enlarged prostate gland.
• Your sex. More than half of all women will have a urinary tract infection at least once in their lives, often with some urinary bleeding. Men are more likely to have kidney stones or bladder stones.
• A recent infection. Kidney inflammation after a viral or bacterial infection (post-infection glomerulonephritis) is one of the leading causes of visible urinary blood in children.
• Family history. A family history of kidney disease or kidney stones makes it more likely that you will develop these problems. Both can cause blood in the urine.
• Strenuous exercise. This is one of the leading causes of visible blood in urine. Distance runners are most at risk, but anyone who exercises vigorously can have some urinary bleeding.

Call your doctor if you have visible blood in your urine that lasts more than 24 hours or you have color changes that don't seem related to food, medications, supplements or dyes. Also see your doctor if you have two or more episodes of bloody urine, no matter how far apart. And seek medical care as soon as possible if you have dark brown urine, especially if you also have pale stools and yellow skin and eyes. These may be signs of a serious liver problem.

In addition to taking a thorough medical history and performing a physical exam, your doctor will recommend certain diagnostic tests, including:

• Urinalysis. A thorough urine analysis is the most important first step. Urine tests are used to look for the presence of red blood cells, high levels of protein - which may indicate a kidney problem — and excreted minerals that can cause kidney stones. A sample of your urine is also likely to be checked for bacteria that cause infection.
• Blood tests. These may be used to measure levels of creatinine and blood urea nitrogen (BUN) — waste products that build up in your bloodstream when your kidneys are damaged and not filtering properly. Blood tests may also look for elevated levels of liver enzymes, and for conditions such as diabetes.
• Other tests. You may have other tests, depending on the results of your history, physical exam and urine analysis. The most common reason for further testing is the presence of red blood cells in the urine.

Discolored urine has no specific treatment. Instead, your doctor will concentrate on treating the underlying condition.

It's usually not necessary to prevent changes in urine color caused by vitamin supplements, medications or foods. And preventing the illnesses that can discolor urine often isn't possible, though you can take certain steps to reduce your risk.

Risk-reducing strategies include:

• Urinary tract infections. Drinking plenty of water, and urinating when you feel the urge and as soon as possible after intercourse may help prevent bladder infections.
• Kidney stones. To help lower the likelihood of kidney stones, drink lots of water and limit salt, protein, and foods such as spinach and rhubarb.
• Bladder cancer. Stopping smoking, avoiding exposure to chemicals and drinking plenty of water can cut your risk of bladder cancer.
• Kidney cancer. To help prevent kidney cancer: Stop smoking, maintain a healthy weight, up your intake of fruits and vegetables, stay active, and avoid exposure to toxic chemicals.