Smelly Urine: 13 Common Causes & What to Do

Updated in July 2022

Smelly urine mostly occurs due to decreased water intake throughout the day. This can also give the urine a dark yellow tinge. A foul smell can also happen after eating certain foods like garlic, onion or asparagus. Oftentimes, the smell can be resolved with simple interventions, like ensuring adequate fluid intake throughout the day or avoiding consumption of these foods. 

Nonetheless, smelly urine can also be a sign of a health problem, like a UTI, uncontrolled diabetes or even an STI. These causes will usually produce other symptoms, like pain with urination, urinary frequency, increased thirst and swelling.

It is important to see you family doctor, urologist or gynecologist if you notice unusually smelly urine, especially if you have other symptoms. That way, the doctor can identify the underlying cause and initiate treatment as necessary. 

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The main causes of smelly urine are: 

1. Low fluid intake 

When you do not drink enough water throughout the day, substances that are usually eliminated in the urine become more concentrated, which can cause a stronger smelling urine. It is also possible for urine to become darker in color. 

Decreased fluid intake can also lead to dehydration, which can further concentrate urine and give it a dark color with a strong smell. Other common symptoms include a dry mouth, headache, excessive fatigue and increased thirst. 

What to do: It is important to ensure adequate fluid intake - you should aim for at least 2L of water per day. You can also increase your intake of food that is naturally rich in water, like watermelon or cucumber. These can help to keep the water hydrated and decrease any foul smells in the urine. 

2. Sulfur-rich foods

Certain foods can make your urine smelly. This is especially true with asparagus, as it is rich in asparagusic acid, which is a sulfuric compound that the body transforms into methanethiol (or methyl mercaptan). This compound can make the urine smell like sulfur, which is comparable to rotting cabbage. 

Other foods can also give your urine a foul smell, like garlic and onion (which contain sulfuric compounds), brussel sprouts, coffee, nuts and fennel. 

What to do: You can try to decrease your intake of these foods, or avoid them altogether, for a few days to see if the smell resolves on its own. If it persists, you should see your family doctor to rule out other causes for the smelly urine. 

3. Pregnancy

The expected hormonal changes that occur during pregnancy can heighten a woman’s sense of smell, which can give them the perception that their urine is smelly. 

The use of prenatal vitamins can also affect urine color or odor. It is also common for many pregnant women to contract urinary tract infections, which can lead to foul-smelling urine as well as pain or burning with urination. 

Check-out our online quiz to assess your risk for a UTI.

What to do: Pregnancy should be monitored by an obstetrician who will advise the best prenatal vitamins for you to take. You should not discontinue your prenatals abruptly without notifying your obstetrician. If you are pregnant have symptoms of a UTI, you should see a doctor for treatment with antibiotics. 

4. UTI

A urinary tract infection is one of the most common causes of smelly urine. The large amounts of microorganisms present along the urinary tract contribute to stronger-smelling urine. 

In addition to a foul odor, some people also report symptoms like pain or burning with urination. dark urine and urinary frequency. 

What to do: Treatment should be monitored by a doctor, and generally involves the use of antibiotics like fosfomycin, nitrofurantoin, amoxicillin or ciprofloxacin. You are advised to increase your fluid intake by drinking more water or natural fruit juices while you are recovering. Increased fluid can help to eliminate urine and eliminate any lingering bacteria. Learn more about UTI treatment, and about the medication or home remedies you can incorporate into your treatment plan. 

5. Kidney failure

Decreased urine output with a strong smell can be a sign of kidney malfunctioning. Kidney that do not work properly tend to produce concentrated urine. 

Symptoms associated with kidney failure can include hand tremors, fatigue, drowsiness and swelling in the eyes, legs and feet due to water retention. See the other symptoms of kidney problems you should monitor. 

What to do: Treatment for kidney failure is typically guided by a nephrologist. It may involve the use of medication to decreased arterial pressure (like lisinopril) or swelling (like furosemide).

In addition, treatment should be complemented by a low protein, salt and potassium diet to decrease kidney overload.

6. Uncontrolled diabetes 

Diabetes that is left untreated is also a frequent cause of smelly urine. The high levels of sugar circulating throughout the body can contribute to urine smell, as well as kidney damage that can happen as a result. 

Other symptoms of uncontrolled diabetes include increased thirst, urinary frequency, fatigue, wounds that are slow to heal or tingling in the hands or feet. 

What to do: Diabetes treatment is usually monitored by an endocrinologist and involves the use of antidiabetics (though the medications used will depend on the type fo diabetes the patient has). Patients should additionally control their sugars through diet and engage in regular physical activity. 

7. STI

Smelly urine can also be a sign of an STI, like gonorrhea, chlamydia or trichomoniasis. STIs can alter your urine’s smell as they are usually associated with foul-smelling discharge and urethral discharge. 

Sexually-transmitted infection can also cause other symptoms, like pain or burning with urination, white or yellow discharge that is pus-like or pelvic pain. 

What to do: You should see your doctor for assessment if you suspect an STI. Treatment will depend on the type of STI identified, and it usually involves the use of specific antibiotics. Read more about the most common STIs and how they are treated. 

8. Bacterial vaginosis

Bacterial vaginosis (BV) is a vaginal infection caused by Gardnerella vaginalis bacteria. This bacteria grows when there is a decrease in good bacteria in the vagina. BV is associated with a fishy-smelling discharge, which can alter urine smell. 

BV can also cause symptoms like intense genital itching, white or gray discharge, as well a sensation of burning. 

What to do: You should see your doctor for treatment, which typically involves antibiotics like metronidazole, clindamycin or secnidazole. Antibiotics can be prescribed as topical ointments, pills or vaginal suppositories. 

9. Pelvic inflammatory disease

Strong-smelling urine can emerge due to pelvic inflammatory disease. This inflammation usually starts in the vagina and progresses to hte uterus, fallopian tubes and ovaries before spreading throughout the entire pelvis. This condition is associated with a yellow or green vaginal discharge, which can affect urine smell. 

Pelvic inflammatory disease is often caused by STIs that are left untreated, like gonorrhea or chlamydia, but it can also occur from other situations, like endometriosis or when there is an increased risk for bacterial transmission (e.g. introducing contaminated sex toys).

What to do: Treatment for pelvic inflammatory disease involves the use of prescription antibiotics, like azithromycin, levofloxacin, clindamycin, which can be administered as injections or taken as pills. 

10. Vitamin supplements 

Vitamin supplements, particularly B-complex vitamins (like thiamine or coline, pyroxidine, or riboflaven), can cause darker or stronger-smelling urine. These vitamins are water-soluble, and therefore they dissolve in water when ingested and are eliminated in the urine.

What to do: Generally, the strong smell disappears within a few days of stopping B-complex vitamins. These types of supplements should only be used if prescribed by a doctor or recommended by a registered dietitian. It is important to only stop taking them when advised to do by a health care professional.

11. Liver disease

Some liver diseases, like liver failure or a liver infection, can increase the production of ammonia, which is eliminated in the urine. Ammonia can give the urine a sweet or mold-lie smell

Symptoms of liver disease also include dark urine, pale stool, yellow skin or eyes, abdominal swelling or pain in the right upper abdomen. Check out the liver disease symptoms you should not ignore. 

What to do: Liver diseases should be assessed by a gastroenterologist, so that a diagnosis is confirmed. Treatment will depend on the underlying cause of the liver disease. 

12. Phenylketonuria 

Urine with a strong, mold-like smell can be a symptom of phenylketonuria, which is a rare, congenital disease that is characterized by the accumulation of phenylalamine in the body. This condition can be diagnosed soon after birth. 

Other symptoms associated with this disease include growth delays, mold-smelling skin and learning disabilities. 

What to do: Treatment involves the maintenance of a strict diet that is low in phenylalamine, which can be found in meat, eggs, oilseeds, processed food, milk and dairy products. 

13. Metabolic disease

Some hereditary metabolic diseases, like tyrosinemia, trimethylaminuria, or cystinuria can cause smelly urine. Urine often smells like fish, eggs our boiled cabbage, while some patients report a sweet smell. 

These metabolic can also affect the smell of sweat, breaths and ear wax.

What to do: Treatment for metabolic diseases should be monitored by a pediatrician, as these conditions are usually diagnosed in infancy. Babies who present with changes to urine smell should be assessed to rule out a diagnosis. Treatment will depend on the metabolic disease identified.