Here’s Why Your Pee Smells

Most of the time, peeing isn’t a notable experience. But then there are days when your nose picks up a certain … funkiness.

Consider it a whiff of information, as the smell of your urine can offer important insight into what’s happening inside your body.

Let’s learn how to sniff out the clues with urologist Rashed Ghandour, MD.

Causes of bad-smelling pee

While urine doesn’t usually smell like anything, various factors — a few of them concerning — can cause pee to take on a strange or unpleasant odor.

“Occasional bouts of smelly pee are completely normal,” Dr. Ghandour reassures. “It reflects the life you’re living.”

Common causes of bad-smelling pee include:

• Dehydration: If you’re dehydrated, the percentage of water in your pee drops and the filtered waste takes a more prominent role. That creates a stronger smell, explains Dr. Ghandour.
• What you eat: Asparagus is infamous for giving urine a pungent odor. Your body converts an acid in asparagus into a sulfur-containing compound, lending your pee a skunky, rotten-egg scent. Brussels sprouts, fish, cumin, onions and garlic can make your pee extra zesty, too.
• What you drink: Coffee and soda drinkers may recognize a certain brewed aroma during a bathroom break. Speaking of brews, Dr. Ghandour says alcohol can also make your pee smell.
• Drugs you’re taking: Medications and supplements can affect pee smell. Vitamin B6 is particularly well known for lending a certain musk to urine, as are several drugs used in chemotherapy. Supplements with lots of thiamin (vitamin B1) or choline have a similar effect.
• Certain health issues: Diabetes, bladder inflammation (cystitis), and bacterial vaginosis are among the many medical conditions that can affect the potency of your pee’s smell.

The causes we’ve laid out are just the tip of the smelly-pee iceberg. Some people even notice a change in their urine’s smell during pregnancy! So, when is nose-plugging pee worth calling a provider about, and when should you go with the flow?

Smells that are a cause for concern

Not all pungent pee is worth worrying about, but if you detect a hint of sweetness, ammonia, popcorn or rotting fish, it’s time to see your primary care provider. Dr. Ghandour explains why.

Pee that smells like ammonia

Pee with a smell reminiscent of ammonia or bleach can indicate a wide range of health concerns, but the most common is a urinary tract infection (UTI).

Urine showing signs of a UTI may also be cloudy or even a bit bloody. Peeing may become painful, too. For an extra twist of cruelty, you might also get the urge to pee more often. Fever and mental confusion are other telltale signs.

If you have multiple symptoms, Dr. Ghandour advises scheduling a visit with a healthcare provider.

You won’t be alone. UTIs send about 10 million people in the U.S. to a healthcare provider every year for antibiotic treatment. Women and older adults are more prone to getting the infection.

Dr. Ghandour says urine can also carry a whiff of ammonia because of:

• Kidney stones
• Kidney disease
• Liver disease
• Menopause
• Prostate infection
• Sexually transmitted infections (STIs)

An ammonia-like odor can also be linked to dehydration, as well as certain foods and vitamins.

“If the smell pops up and disappears quickly, there’s little reason for concern,” he clarifies. “But if it lingers, get checked by a medical professional.”

Pee that smells fruity or sweet

Pee with a sugary or fruity fragrance can serve as a warning sign of diabetes or high blood sugar. The sweet smell comes from your body unloading excess glucose (sugar).

In children, particularly newborns, sweet-smelling tinkle might indicate maple syrup urine disease. This rare, life-threatening metabolic disorder prevents the body from breaking down specific amino acids found in food.

The underlying message here? Urine that smells sweet shouldn’t be ignored. Dr. Ghandour urges you to check in with a healthcare provider.

Pee with a foul odor

If you haven’t had one of the foods that’s known to give pee a sulphuric scent, a foul smell emanating from your toilet bowl could be a sign of a rare metabolic disorder.

Trimethylaminuria, also known as fish odor syndrome, is a rare condition where your body can’t process trimethylamine — which, as it happens, is a particularly stinky chemical.

The unfortunate result? Pee, breath and sweat that smells like rotting fish. (Hence the name.) This condition can be inherited or acquired. While it’s an unpleasant condition, it isn’t dangerous.

Not so for another condition that can cause smelly pee: tyrosinemia. Tyrosinemia has three distinct types, all of which are dangerous. Infants with this genetic disorder can’t break down an amino acid called tyrosine, which is foundational to most proteins. The resulting tyrosine buildup can cause major complications.

Tyrosinemia is very rare, but if your infant’s urine is foul-smelling, Dr. Ghandour says you should talk to your baby’s pediatrician anyway, just to be safe.

Pee that smells like popcorn

There are lots of possible reasons for pee to smell like popcorn — some serious, some not. If taking a whizz only makes your bathroom smell like a movie theater temporarily, it’s probably from something you ate or dehydration. But if it happens frequently, Dr. Ghandour says it could point to:

• Diabetes
• Ketosis
• A UTI
• A metabolic disorder

“If your baby’s urine smells like popcorn, they might have a rare genetic condition called phenylketonuria (PKU),” Dr. Ghandour adds. The good news? Many countries around the world, including the U.S., screen newborns for PKU before they ever leave the hospital. If you live in one of those countries, you can cross this one off the list of possibilities.

Final thoughts

There’s usually a pretty basic explanation for urine that smells a bit different. It’s just the way your body functions, reiterates Dr. Ghandour. In most cases, that funk should disappear within a day or so.

But if the smell stays and is accompanied by other symptoms, it’s something that deserves further investigation. Don’t ignore it.