That sharp, ammonia-like smell you’re noticing is almost certainly real, and the connection to cat litter makes sense: the same chemical process that makes a litter box stink is happening in your urine. Your body produces ammonia as a waste product of protein metabolism, and under normal conditions, most of it gets converted and flushed out without much odor. When something shifts that balance, whether it’s dehydration, diet, an infection, or a deeper health issue, the ammonia concentration rises and the smell becomes impossible to ignore.
Why Urine and Cat Litter Smell the Same
The culprit is ammonia. Your liver converts ammonia, a toxic byproduct of breaking down protein, into a compound called urea. Urea is relatively odorless when it leaves your body in fresh urine. But bacteria, both inside and outside the body, produce an enzyme called urease that breaks urea back down into ammonia and carbon dioxide. This is exactly what happens in a cat’s litter box: bacteria in the litter split urea apart, releasing that unmistakable sharp smell. When the same process ramps up in your own urinary tract, or when your urine sits concentrated in your bladder for a long time, you get the same result.
Dehydration Is the Most Common Cause
When you don’t drink enough water, your kidneys produce less urine, so all the waste products in it become more concentrated. The same amount of ammonia in a smaller volume of liquid means a stronger smell. This is by far the most frequent reason people suddenly notice their urine smelling pungent. The fix is straightforward: increase your fluid intake and see if the odor fades within a day or two. If your urine is dark yellow or amber, you’re likely not drinking enough.
High-Protein Diets Raise Ammonia Output
Protein is the main dietary source of nitrogen, and nitrogen is what your body ultimately converts into ammonia. The more protein you eat, the more ammonia your kidneys need to excrete. Research in renal physiology shows just how directly the two are linked: when people switched to a low-protein diet, their urinary ammonia dropped by 64% on the first day and 85% by the second day. The reverse is equally true. If you’ve recently started a high-protein or ketogenic diet, your body is processing significantly more nitrogen, and your urine will reflect that.
Ketogenic diets add another layer. When your body burns fat instead of carbohydrates for fuel, it produces ketones. Some of these ketones are excreted in urine and carry their own distinct smell, which some people describe as sharp or chemical. Combined with higher ammonia from protein intake, the overall effect can be quite strong.
Urinary Tract Infections
Certain bacteria that cause UTIs are especially good at producing urease, the enzyme that splits urea into ammonia. One of the most well-studied is Proteus mirabilis, which generates so much ammonia that it actually raises the pH of urine, making the local environment more alkaline. This elevated pH can also lead to the formation of kidney stones over time if the infection goes untreated.
A UTI doesn’t always cause the classic burning sensation. Sometimes a strong ammonia or foul smell is the first noticeable sign, especially in older adults. Other clues include cloudy urine, a frequent urge to go, pelvic pressure, or urine that looks pink or reddish. If a doctor suspects a UTI, a simple urine test checks for markers of infection: the presence of white blood cells (detected through an enzyme they release) and nitrites, which are produced by many of the bacteria responsible for urinary infections. Nitrites are not normally present in urine, so a positive result is a strong indicator.
Holding Urine Too Long
The longer urine sits in your bladder, the more time bacteria have to break down urea into ammonia. Medical references describe this as “prolonged bladder retention,” and the resulting smell is characteristically ammoniacal. If you regularly hold your urine for hours because of work, travel, or habit, that alone can explain the cat-litter odor, particularly if you’re also not drinking much water throughout the day.
Liver and Kidney Problems
Your liver and kidneys work together to process and remove ammonia. When either organ isn’t functioning well, ammonia can build up in the blood and eventually show up at higher concentrations in urine.
Liver disease reduces the organ’s ability to convert ammonia into urea in the first place. In severe cases, ammonia accumulates to levels that affect the brain, a condition called hepatic encephalopathy, which can cause confusion, drowsiness, and personality changes. Kidney failure creates the opposite bottleneck: the liver does its job, but the kidneys can’t efficiently filter and excrete the resulting urea. Rare genetic conditions affecting the urea cycle can cause similar buildup, though these are typically identified in childhood.
A change in urine smell alone doesn’t mean you have organ damage. But if the smell persists for weeks despite good hydration and a normal diet, or if you notice other symptoms like fatigue, swelling in your legs, yellowing skin, or dark-colored stool, those patterns together warrant investigation.
Pregnancy and Heightened Smell
Pregnancy can make you more aware of smells you previously filtered out. In the early weeks, many pregnant people develop hyperosmia, an increased sensitivity to odors. Ammonia is always present in urine at low levels, but a nose that’s suddenly more sensitive can pick up what it used to miss. Combine that with the dehydration that often accompanies morning sickness, and the ammonia smell can seem like it appeared out of nowhere. In most cases, the smell isn’t actually stronger; your perception of it has changed.
What the Color and Clarity Tell You
Smell alone is just one piece of the picture. Pairing it with what you see can help narrow things down:
- Dark yellow or amber, strong smell: Almost always dehydration. Drink more fluids and reassess in 24 hours.
- Cloudy with a pungent odor: Suggests a possible infection, especially if accompanied by discomfort or urgency.
- Pink or reddish tint: Blood in the urine. This needs prompt evaluation regardless of smell.
- Pale yellow, still smells strong: Consider your diet. High protein intake or certain supplements (B vitamins, asparagus) can alter the smell even when hydration is adequate.
Practical Steps to Reduce the Smell
Start with hydration. Aim for enough water that your urine stays a light straw color throughout the day. If you’re on a high-protein or keto diet, increase your water intake proportionally, since your kidneys are working harder to clear nitrogen waste. Don’t make a habit of holding your urine for extended periods; emptying your bladder regularly keeps ammonia from building up.
If the smell persists for more than a week despite drinking plenty of water, or if you develop pain, fever, blood in your urine, or vomiting alongside it, those are signals that something beyond diet or dehydration is going on. A standard urinalysis can check your urine’s pH, screen for infection markers, and flag other abnormalities, giving a clear picture of what’s driving the odor.