Medical Doctors List 12 Reasons Urine Can Smell Unusual

Weird-smelling pee doesn’t necessarily mean there’s a medical issue. Dr. Eswara explains that urine carries out all the water-soluble compounds your body processes, so its smell can reflect what you’re putting in. “Certain spices, chemicals, and their breakdown products will end up in your urine and give it an odor,” he says.

Still, there are some cases when a change in urine odor suggests something more is going on, such as an infection or disease. 

You’re dehydrated

If your pee has an ammonia-like odor, you might be dehydrated, Dr. Eswara says. “The ammonia smells come from the breakdown products of protein,” he says. Normally, fluids help dilute these waste products in urine. But if you’re not drinking enough water, your pee gets more concentrated—and that natural ammonia smell gets more intense. 

But dehydration usually has another telltale sign: dark-colored pee. “People should strive to have urine that’s a light yellow color,” says William O. Brant, MD, FACS, FECSM, chief of urology at the Veterans Affairs Medical Center in Salt Lake City. “If it’s dark yellow or an amber color, they’re probably not drinking enough water.”

You started taking a new vitamin

Many vitamins are water-soluble, which means any excess your body doesn’t need is flushed out in urine, says Stephanie Kielb, MD, clinical professor of urology at the University of Michigan Medicine. 

That’s why certain supplements can give pee a fluorescent yellow or greenish hue—and some can change its odor, too. The Cleveland Clinic notes that, in particular, B-complex vitamins can make pee smell fishy or musty. The good news is that these changes are typically harmless, so there’s no need to skip your daily supplement.

You ate a hearty helping of vegetables

Vegetables are great for you, but don’t be alarmed if a plate of plants makes your pee smell a little odd. Asparagus is the most famous example: Thanks to its sulfur-containing compounds, your pee can take on a funky odor in as little as 20 minutes after eating it.

Other veggies, such as Brussels sprouts, onions, cabbage, and turnips, can have a similar effect. When your body breaks them down, it releases methyl mercaptan—a sulfur-containing gas with a distinctive, pungent smell. “The vegetable is still healthy and a good part of your diet,” Dr. Brant says. “These chemicals just happen to be things that we react to.” 

You’ve indulged in other smell-inducing foods and drinks

Veggies aren’t the only dietary culprit behind smelly urine, according to 2024 research published in Nutrients. Other foods and beverages release strong-smelling compounds that make their way into your body’s urine, including:

• Fish
• Meat
• Eggs
• Alcohol
• Coffee
• Cooked beans

You’re not peeing enough

If you need to go, let it flow. Holding in urine for too long gives bacteria more time to multiply—and this can make your urine smell strong and stale, explains Craig Comiter, MD, a board-certified urologist at Stanford Health Care. Dr. Comiter refers to this habit as “teacher’s bladder” or “trucker’s bladder,” as people in jobs with hectic, rigid schedules tend to delay bathroom breaks. 

Over time, ignoring the urge to go can also raise your risk of urinary tract infections (UTIs) and bladder problems, according to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). 

You’re committed to Keto

Low-carb, high-fat diets put your body into ketosis, a metabolic state where your body uses fat for energy instead of carbs, Dr. Kielb explains. “During this state, your urine and breath may both have an odor.” 

That’s because when carbs aren’t available, your body produces ketones to help break down fat for fuel. Once they’ve done their job, these compounds get released through your breath, sweat, and urine, producing a characteristic scent people often describe as fruity, nail-polish-like, or similar to popcorn. A low-carb diet is a common trigger, but fasting or prolonged exercise can also have this effect, according to 2024 research published in the Journal of Diabetes Science and Technology. 

This high-fat, low-carb eating plan has its fans—but it has its drawbacks, too. Here’s what the experts say you should know before going Keto. 

You’re over-cleaning “down there” 

Skip the soaps, fragrances, and douches—the only thing you should be using to cleanse your vaginal area is water, advises Dr. Brant. Cleansing products can disrupt the vagina’s natural pH and delicate balance of bacteria, which 2023 research in Microorganisms shows can increase the risk of issues like bacterial vaginosis and UTIs. 

These shifts in vaginal pH or bacteria may also change how your pee smells. “The vagina, the urine, a lot of your body is supposed to have a certain type of acidity,” says Dr. Brant. “If you mess with the acidity, things don’t work out very well.”

You may have a urinary tract infection (UTI)

UTIs can cause urine to take on a foul odor, often described as similar to rotten food or sweaty socks. These infections occur when bacteria enter the bladder through the urethra, explains Dr. Comiter. 

But bacteria in the urine can make your pee smell even if you don’t have an active UTI. A condition called asymptomatic bacteriuria—when bacteria are present without any symptoms—is especially common among older women. “About one-third of women over the age of 65 can have bacteria in the urine on and off,” says Dr. Comiter. “But it doesn’t represent a risky infection because it’s just bacteria that flourish in the urine and then disappear.”

You may have diabetes

Sometimes, off-smelling urine signals that something more serious is going on. “If you have uncontrolled diabetes, your body tries to get rid of extra blood sugar—or glucose—in the urine, creating a sweet smell,” Dr. Kielb says. This symptom is usually associated with advanced diabetes. 

Sweet-smelling urine can also be a warning sign of diabetic ketoacidosis (DKA). This is a life-threatening complication that happens when your body can’t use glucose for energy and starts breaking down fat instead, according to the American Diabetes Association (ADA). People with type 1 diabetes are more at risk, says the ADA, but it can occur in people with type 2 as well.

You may have kidney problems

The 2024 Nutrients research notes that kidney stones can also contribute to foul-smelling urine. Stones increase the levels of salt and ammonia in your pee, and the blockage itself slows down your flow, making these substances even more concentrated. 

Urine with a strong ammonia, rotten eggs, or spoiled meat scent can also be a sign of kidney disease, according to the research. If your kidneys aren’t functioning properly, they can’t efficiently filter waste—and this can lead to a build-up of smelly compounds in your pee. 

You have a Pseudomonas infection

If your urine smells like metal, that could be a sign of a Pseudomonas infection. This type of infection is common in hospital and nursing home patients because the bacteria that cause it thrive in these environments. “Once there’s a bacteria in the hospital or in the nursing home, it hangs around,” Dr. Comiter says. “Once it gets there, it stays there. It’s part of the flora bacterial environment.” (But take note: A Pseudomonas infection is also one of the scary diseases you can pick up at the beach.) 

People who are sick, elderly, or have a weakened immune system are particularly susceptible—and it needs to be treated, usually with antibiotics. This infection will typically come with other symptoms based on where the infection is in your body, according to the Cleveland Clinic. 

You don’t pee into a toilet

People who use catheters and urine drainage bags may complain of an odor in their bags. “That bagged urine really smells because once it’s out of you, the bacteria flourish,” says Dr. Comiter, who offers reassurance that it’s “not dangerous”: “It’s just the nature of an unsterile urine specimen.”

He suggests dropping an aspirin in the bag because salicylic acid neutralizes the pungent smell. If the odor persists or your urine becomes cloudy, seek a physician’s care.