The single biggest factor in how your urine smells is how much water you’re drinking. Urine that carries a lot of metabolic waste and relatively little water produces a strong ammonia-like odor, while dilute urine has almost no smell at all. Beyond hydration, though, several other factors play a role, and most of them are surprisingly easy to adjust.
Why Urine Smells Strong in the First Place
Your kidneys filter waste products out of your blood, and those waste compounds end up dissolved in your urine. The two main odor culprits are ammonia (from protein metabolism) and sulfur compounds (from certain foods and amino acids). When your urine is concentrated, these molecules are packed more tightly together, and more of them escape into the air as gas, which is what you actually smell.
Interestingly, the chemistry of your urine’s acidity affects which odors are strongest. Ammonia becomes more volatile in alkaline (less acidic) urine, meaning it escapes into the air more easily and smells more pungent. Sulfur compounds, on the other hand, become more volatile when urine is acidic. So your urine’s pH essentially determines which type of smell dominates. Most people’s urine sits in a mildly acidic range, which keeps ammonia somewhat contained, but if your diet or hydration shifts that balance, the smell can change noticeably.
Drink More Water (It Really Is That Simple)
This is the most effective thing you can do. The Mayo Clinic puts it plainly: urine with a lot of water and little waste has little to no odor. When you’re even mildly dehydrated, waste concentrations spike, and the smell intensifies. A good visual check is color. Pale straw-colored urine is well-diluted. Dark amber urine is concentrated and will smell stronger.
You don’t need to force excessive amounts of water. For most people, drinking enough to keep urine light yellow throughout the day does the job. Morning urine will almost always smell stronger because you haven’t had fluids for hours, and that’s completely normal. If your urine is consistently dark and pungent despite drinking fluids, that’s worth paying attention to.
Foods That Change Urine Odor
Asparagus is the most famous offender. It contains a sulfur compound that your body breaks down quickly, and most people notice a distinct smell within 15 to 30 minutes of eating it. The odor is harmless and passes once you’ve fully metabolized the asparagus, usually within a few hours.
Other foods that can alter urine smell include garlic, onions, cruciferous vegetables like broccoli and Brussels sprouts (all sulfur-rich), coffee, and certain spices like curry and cumin. Fish and high-protein meals increase the nitrogen waste your kidneys filter, which can boost ammonia odor. None of these are harmful, but if you’re bothered by urine smell, cutting back on the most sulfur-heavy foods makes a noticeable difference.
Fruits and foods rich in vitamin C tend to make urine slightly more acidic, which actually helps keep ammonia in its less-volatile form. Citrus fruits, berries, and cranberry juice can mildly shift the balance toward less ammonia odor, though the effect is modest compared to simply drinking more water.
Supplements and Vitamins That Cause Odor
B vitamins are well-known for changing both the color and smell of urine. High-dose B supplements can give urine a strong, sometimes sulfurous or medicinal odor that clears once the excess vitamins are excreted, usually within several hours.
Choline, found in many multivitamins, prenatal vitamins, and B-complex supplements, can cause a fishy urine odor. This is especially pronounced in people with a genetic condition called trimethylaminuria, where the body can’t properly break down a compound called trimethylamine. People with this condition accumulate TMA, which gets excreted through urine, sweat, and breath with a distinctly fishy smell. Even without the genetic condition, high choline intake can sometimes produce a milder version of this effect.
If you’ve noticed a new urine odor that started around the same time as a new supplement, try stopping it for a few days. That’s usually enough to confirm whether the supplement is the cause.
Chlorophyll Supplements as Internal Deodorants
Chlorophyllin, a water-soluble derivative of chlorophyll, has been used since the 1940s as an internal deodorant. It was originally applied to foul-smelling wounds, then given orally to patients with colostomies to control fecal odor. Several case reports have found that doses of 100 to 300 mg per day reduced both urinary and fecal odor in incontinent patients. One small study in patients with trimethylaminuria found that 60 mg taken three times daily for three weeks significantly lowered the concentration of the fishy-smelling compound in urine.
The evidence is real but limited. A placebo-controlled trial found that 75 mg three times daily was no more effective than placebo at reducing fecal odor in ostomy patients, so the results are mixed. Chlorophyllin supplements (often sold as “liquid chlorophyll” or chlorophyll capsules) are generally considered safe, but they’re not a guaranteed fix. They’re most likely to help if your odor issue is related to specific compounds like trimethylamine rather than simple dehydration.
When Urine Odor Signals Something Else
Most urine odor is benign, caused by concentration, food, or supplements. But certain smells can point to a health issue worth investigating.
- Sweet or fruity smell: This can indicate uncontrolled diabetes. When blood sugar is too high, your body starts breaking down fat for energy and produces compounds called ketones, which spill into urine and give it a sweet or fruity odor.
- Musty smell: Liver disease and certain metabolic disorders can produce a musty urine odor. This happens when the liver can’t properly process waste products, allowing unusual compounds to accumulate.
- Foul or unusually strong smell with burning or urgency: Urinary tract infections cause bacteria to multiply in the urinary tract, producing waste products that give urine a particularly unpleasant odor. This is usually accompanied by other symptoms like pain during urination, frequent urges to go, or cloudy urine.
- Persistent fishy smell: If this doesn’t go away after adjusting diet and supplements, trimethylaminuria or a bacterial infection could be the cause.
A one-time unusual smell after a meal or new supplement is rarely concerning. A persistent change in odor that doesn’t respond to increased water intake and dietary changes is the pattern worth getting checked out.
A Quick Daily Checklist
If you want less noticeable urine odor day to day, these steps cover the most impactful changes:
- Stay consistently hydrated. Aim for pale yellow urine throughout the day, not just in the morning.
- Cut back on sulfur-heavy foods like asparagus, garlic, and cruciferous vegetables if the smell bothers you.
- Review your supplements. B vitamins, choline, and certain protein powders are common odor contributors.
- Eat more fruit. Citrus and berries can mildly acidify urine, helping keep ammonia less volatile.
- Don’t hold it. Urine that sits in the bladder for a long time becomes more concentrated and develops a stronger odor by the time you go.
For most people, hydration alone handles 80% of the problem. The remaining adjustments are fine-tuning.