What Causes Oily Urine?

Most people don’t look down while urinating. But if you happen to do it, and you notice oily urine, it can be a cause for concern.

This isn’t an uncommon symptom, but it should still be investigated.

Your urine, like your stools, can be a good detector of underlying health conditions.

In this article, we’ll show you the common causes of oily urine as well as when it’s time to see a doctor.

The Urinary System

urinary systemBefore talking about the causes of your symptom, it helps to understand the urinary system.

This might give you more clues as to what could be causing it. The main parts of the urinary system are:

  • Kidneys
  • Bladder
  • Ureters
  • Urethra

It all starts with the kidneys. Here, blood is filtered before re-entering the circulation.

The body does this to remove toxins and unneeded materials from the blood.

The filtered material is sent to the bladder, which serves as a temporary holding facility.

After a while, the urine makes its way down the ureter and through the urethra.

If something is wrong at any point along this journey, it can cause oily urine.

Bottom Line: The urinary system is made up of the kidneys, bladder, ureters, and urethra. A malfunction is any of these is bad.

Cause #1: Urine Ketones

As we talked about in this article, ketones are what the body produces when it’s in “starvation mode”.

If you haven’t eaten for a long time, or if you’re on a low-carb diet, then it’s not uncommon to see oily urine.

People with diabetes or problems relating to blood sugar are also more susceptible to having ketones in their urine.

Ketones are produced whenever the body enters a state of ketosis.

This is when the body can no longer use carbohydrates as fuel and so it switches to protein.

Bottom Line: One potential cause to oily urine is that your body has entered a state of ketosis. Diabetes is also a possibility.

Cause #2: Dehydration

Normally, urine should be a light-yellow color and should have the consistency of water.

If it starts to change color and/or consistency, then this could be a sign of dehydration.

If you’re suffering from an illness, then you’re at a higher risk of being dehydrated. Make sure that you drink more water during this time.

If you’re an athlete at an athletic event, then you may have sweated all your fluids away. In this case, you should drink more.

Bottom Line: Another common cause for oily urine is dehydration. It’s commonly seen in people who are sick as well as athletes.

Cause #3: Vitamin Overdose

Various vitamins and supplements can change what your urine looks like.

There’s no specific one to look out for. Simply make sure that you’re not taking too much of any vitamin.

Most people don’t realize that vitamin toxicity, especially through supplementation, can have serious health consequences.

For example, consuming too much vitamin A in supplement form can cause a dent to appear on the skull.

That’s just one example of many. Your oily urine could be due to taking too much of a certain vitamin, whatever one it may be.

Bottom Line: Click here to get the fact sheets on how much of each vitamin you’re supposed to consume daily.

Other Signs to Look Out For

If your pee has an oily appearance, and that’s your only symptom, then it’s probably not serious.

However, if it’s accompanied by other symptoms, then you should investigate it further. Here are some additional symptoms to look out for:

  • Foul Smell: Urine that smells bad can be a sign of many things. For instance, it can be caused by UTIs, dehydration, or eating too many onions. If you have this along with oily urine, then you may want to see a doctor.
  • Burning: Does it burn when you pee? If so, this is a telltale sign that you have some sort of infection. It’s possible that you have a UTI, which is caused by bacteria. If it’s a UTI, you should take antibiotics to get rid of the infection.
  • Changes in Color: Pee should be a light-yellow color. If it’s not that color, then it should be a cause for concern. For example, urine that’s very dark-yellow in color could be a sign that you’re dehydrated. Be on the lookout for “odd” colored pee.
  • Changes in Consistency: The consistency of your urine is very important. Normal, healthy urine should have a relatively watery consistency. If the consistency is thinner or thicker than this, then it can be a sign of an underlying medical problem.

Some patients experience oily urine and nothing else while others experience many accompanying symptoms.

Generally, the more symptoms present, the more likely it is something that should be looked at by a doctor.

Bottom Line: Some accompanying symptoms to look out for include a foul smell, burning, changes in color, and changes in consistency.

When to See a Doctor

For the most part, oily urine isn’t anything to freak out over. You saw that a relatively common cause of this symptom is ketosis.

When you’re fasting, or when you’re on a low-carb diet, it’s not uncommon for your urine to take on this consistency/appearance.

Unless there are other accompanying symptoms present- burning, pain, etc.- then it’s most likely benign and should go away on its own.

If you have worries, be sure to talk to a doctor. They’ll be able to address all your questions.

Ask a Question: If you want to ask a medical doctor a question that hasn't been answered in one of our articles go to: Ask a Medical Doctor About your Symptoms

Did you find the information in this article helpful?


  • I’m not on Ketogenic diet nor do I have diabetes. I drink lots of water a day and take vitamins B, C, D like once a week. I have done Cystoscopy & Bladder Scope with no signs of medical issues. I have no clue why I have rainbow color oil slick in the urine. One thing I notice is that I am not easy to gain weight, so I am skinny.

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