Asparagus Pee

What's that smell? And why can't some people smell it?
a woman holding her nose and closing the toilet lid with her feet

You’ve enjoyed a lovely dinner with a side of crisp-tender roasted asparagus. A little while later you notice an unusual and pungent aftereffect: smelly urine.

Some of us have never experienced this strange phenomenon. Others, well, we aren’t so lucky. What gives?

It’s not just us modern humans who have experienced asparagus urine’s strange odor. Eighteenth-century Scottish mathematician and doctor John Arbuthnot and French botanist Louis Lémery, as well as the illustrious Ben Franklin, all took note of asparagus’ ability to transform liquid waste into a fetid olfactory experience.

Why Does Asparagus Make Pee Smell?

The culprit of such a malodorous scent is likely nontoxic asparagusic acid found only in, you guessed it, asparagus. This sulfur-containing compound is what gives the healthy green veggie its standout smell when dispelled through urine.

Other compounds known as thiols are also to blame for asparagus pee’s skunk-like rotten egg smell. Methanethiol is the most common of the bunch and is associated with bad breath and fecal odors.

These odiferous volatile compounds break down via the enzymatic process and are released as vapors when one urinates.

How Long Does It Take?

The unique olfactory experience of such vapors can be a swift one, occurring as soon as 15 minutes after asparagus consumption.

How Long Does It Last?

The smell coming from one’s urine can last up to 14 hours for some unlucky individuals!

Why Can't I Smell Asparagus Pee?

If you’re part of the approximately 60 percent of the population that can’t smell asparagus pee, give thanks to specific genes that code for smell receptors. You’re what’s known as asparagus anosmic.

The difference between someone who can smell their urine after eating asparagus and someone who cannot is attributed to variations of at least 800 different genes, which are associated with the ability or inability to smell the telltale tang known as asparagus pee.

Your asparagus pee still stinks. You just can’t smell it.

Study findings show that slightly more women (62 percent) than men (58 percent) cannot smell asparagus pee.

Researchers aren’t completely sure why women can’t detect the smell as much as men. They surmise one difference may be attributed to the modesty and embarrassment of female study participants having to admit they had funky smelling urine.

Another contributing factor might be simple female anatomy. Due to a woman’s sitting position during urination, she may not notice the disagreeable scent as much.

What Does Asparagus Pee Smell Like?

For those of you wondering what asparagus pee smells like, it’s been described as a combination of rotting cabbages and sulfur-rich rotten eggs. Pleasant, no?

Asparagus is Not The Enemy

Before we completely vilify this healthy green vegetable, it’s fair to note that other foods can cause malodorous urine in some people as well:

  • Brussels sprouts
  • onions
  • garlic
  • coffee

Rich in vitamins A, C, and E, as well as other nutrients like fiber, folate, iron, and zinc, asparagus is one nutritious veggie. Don’t let its funk stop you from feasting on it.

Click to See Our Sources

“Ability to smell ‘asparagus pee’ driven by genetic variations” by Hannah Nichols,, 12/27/16

“Asparagus pee is real, but only some of us can smell it” by Kate Bratskeir, The Huffington Post,, 3/31/22

“We unravel the science mysteries of asparagus pee” by Angus Chen,, 12/14/16

“Why does asparagus make your pee smell?” by Jillian Kubala, MS, RD and Ariane Lang Bsc, MBA,, 12/23/19


Lisa Fabian

Contributing Editor

Lisa Fabian is an award-winning freelance writer with more than 25 years of experience in the publishing industry. She's enjoyed covering topics as diverse as arts and crafts, boating, food, and health and wellness.