Why does my pee smell? Five possible causes of smelly urine

Wondering 'why does my pee smell'? Here are five common causes, according to an expert

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If you've ever found yourself in the bathroom wondering 'why does my pee smell?, you're not alone; along with tongue pain and sleep problems, it's a commonly Googled question. Often, it's not a huge cause for concern though. 

There can be a number of reasons why a strong odor can be detected in urine during a trip to the bathroom, and usually it's pretty harmless—be it dehydration or simply something you ate.

Here, we explore the most common causes of smelly urine and what you can do about it. 

Reasons why your pee might smell 

1. You could be dehydrated 

If your urine has turned a dark yellow colour, and you've simultaneously asked
yourself 'why does my pee smell?', you could be dehydrated. 

"Mild dehydration usually changes the color of the urine from a pale yellow color similar to champagne to orange honey-type color, or even brown," explains Maya Mendoza, Co-Founder and Creator of PeeSting.

"Strong, dehydrated urine can become quite pungent and smell like ammonia too. People are quite familiar with that smell, as ammonia is used in many household cleaning products," Maya adds. 

If your urine is dark and smelly due to dehydration, the solution is simple. Drink plenty of fluids, particularly water and squash, until your pee returns to a pale clear color.

"It takes about three hours for what you drink to show in your urine so don't expect it to lighten up immediately," Maya adds. 

2. It could be related to the foods you've eaten

Asparagus is a delicious green vegetable that comes with one very noticeable side effect—it makes your pee smell foul. According to the British Medical Journal, 40% of the population say they can smell “asparagus pee” after consuming the veg—which is not pleasant when you’re using a public bathroom and someone rushes into the cubicle after you.

It’s not just asparagus that can change the scent of your urine though; Brussels sprouts, onions, garlic, curry, and even alcohol can alter the smell, too.

Unfortunately, the only way to combat this particular problem is to stop consuming the culprits, or come to terms with the fact you might have smelly urine after eating an asparagus dish. 

3. You have a UTI 

If your pee is cloudy, smelly and it hurts or burns when you pass it—or if there’s pain in your lower abdomen—chances are you have a UTI. 

"Generally speaking there are some obvious changes to your urine when you have a bacterial infection (such as cystitis) in your bladder or urethra," says Maya.

"The depth of the changes will depend on the severity of the infection and your urological health history. The signs to look for in your pee include cloudy urine. You may notice your urine going darker or a pinkish color. This can mean there is blood in your pee. Often the change in color and cloudiness is accompanied by a strong—and often quite foul—smell," Maya adds. 

If you think you might have a UTI you should speak with your doctor for medical advice and start treatment as soon as possible. 

4. You're pregnant 

Strong smelling urine is one of the early symptoms of pregnancy (as your hormones change, causing urine to become more pungent), so this could be a sign that you're expecting.  

"Pregnancy changes your urine and, at the beginning of pregnancy, you might find yourself needing to pee more often," Maya explains, "This happens because when pregnant you experience an increase of about 25% in your circulating blood, and a lot of that moves through your kidneys, which creates more urine. Sometimes at the start of pregnancy, the urine can seem brighter in color, a bit more fluorescent. This may be due to extra filtering by the kidneys and flushing out of B vitamins."

However, just because your pee smells it doesn't automatically mean you're pregnant of course. There are other changes to look out for, Maya explains. 

"Other changes to urine in early pregnancy include the appearance of white particles, which is simply an increase in a normal and healthy, milky vaginal discharge called leukorrhea, which keeps your vagina moist and clean," Maya says.

"Pregnancy changes and suppresses your immune system and women can become more prone to cystitis and also vaginal yeast infections. Yeast infections have a discharge that can make your urine look cloudy. Yeast infections can make women more vulnerable to BV and UTIs as sore, inflamed vaginal tissue is a perfect breeding ground for bacteria," she adds. 

If you think you might be pregnant take a pregnancy test and speak to your doctor for further advice.

5. You're taking medication 

Certain medications can change the color and smell of your urine, explains Maya. "Some culprits include diabetic medications that lower blood sugar by inhibiting the kidneys from reabsorbing sugar back into your blood—so you pee the sugar out." 

Other medications that affect urine color, and bring on a smell that's something like rotten eggs, include penicillin and sulfonamide antibiotics, antimalarials and medication for rheumatoid arthritis. 

If you are concerned about how your medication is affecting your health, you should speak to your doctor for further advice. 

When to see a doctor if you have smelly urine

Most of the time, smelly urine is totally harmless. But there are some instances where it may suggest an underlying problem.

If you are experiencing lower back pain, pain when peeing, and blood in your pee, you may have kidney stones. If your smelly pee is accompanied by jaundice, tummy pain, nausea, and vomiting, there is a chance that you could be experiencing liver failure. In both instances, you should see your doctor or emergency services as soon as possible.

These things are much less common reasons for smelly urine, however, so if you notice a scent in your urine don't jump to conclusions—it's likely to be nothing to worry about.