# What compounds make the odor of urine? **URL:** \ **Category:** Factual Questions\ **Created:** [June 22, 2018, 6:20am UTC](https://boards.straightdope.com/t/what-compounds-make-the-odor-of-urine/816562 "2018-06-22T06:20:00Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![Contemplation](https://avatars.discourse-cdn.com/v4/letter/c/6de8d8/32.png) [@Contemplation](https://boards.straightdope.com/u/Contemplation)\ **Post date:** [June 22, 2018, 6:20am UTC](https://boards.straightdope.com/t/what-compounds-make-the-odor-of-urine/816562/1 "2018-06-22T06:20:00Z")
Pee has a distinct odor that people say comes from ammonia, but an actual bottle of ammonia smells different than urine. ---
**Author:** ![Nava](https://avatars.discourse-cdn.com/v4/letter/n/da6949/32.png) [@Nava](https://boards.straightdope.com/u/Nava)\ **Post date:** [June 22, 2018, 6:28am UTC](https://boards.straightdope.com/t/what-compounds-make-the-odor-of-urine/816562/2 "2018-06-22T06:28:23Z")
Mainly urea. ---
**Author:** ![Terminus\_Est](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/terminus_est/32/3087_2.png) [@Terminus\_Est](https://boards.straightdope.com/u/Terminus_Est)\ **Post date:** [June 22, 2018, 8:14am UTC](https://boards.straightdope.com/t/what-compounds-make-the-odor-of-urine/816562/3 "2018-06-22T08:14:06Z")
Fresh urine contains urea but shouldn’t contain ammonia. After excretion, urea is decomposed by bacterial action into ammonia. ETA: Other compounds from your diet, e.g. asparagus, can also find their way into urine. ---
**Author:** ![Ignotus](https://avatars.discourse-cdn.com/v4/letter/i/ecc23a/32.png) [@Ignotus](https://boards.straightdope.com/u/Ignotus)\ **Post date:** [June 22, 2018, 5:19pm UTC](https://boards.straightdope.com/t/what-compounds-make-the-odor-of-urine/816562/4 "2018-06-22T17:19:26Z")
> [@Nava](#): > > Mainly urea. My recollection from lab work in biochemistry class in college is that urea is odorless! ---
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [June 22, 2018, 6:25pm UTC](https://boards.straightdope.com/t/what-compounds-make-the-odor-of-urine/816562/5 "2018-06-22T18:25:08Z")
> [@Nava](#): > > Mainly urea. Or, in my case, _manly_ urea. ---
**Author:** ![Schnitte](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/schnitte/32/9033_2.png) [@Schnitte](https://boards.straightdope.com/u/Schnitte)\ **Post date:** [June 22, 2018, 7:14pm UTC](https://boards.straightdope.com/t/what-compounds-make-the-odor-of-urine/816562/6 "2018-06-22T19:14:03Z")
Urea is odourless; the smell comes mainly from substances into which urine decomposes (which is also the reason why fresh urine smells much less pungent than old one). ---
**Author:** ![Contemplation](https://avatars.discourse-cdn.com/v4/letter/c/6de8d8/32.png) [@Contemplation](https://boards.straightdope.com/u/Contemplation)\ **Post date:** [June 23, 2018, 7:19am UTC](https://boards.straightdope.com/t/what-compounds-make-the-odor-of-urine/816562/7 "2018-06-23T07:19:12Z")
so this brings us back to Ammonia, which urine does not smell like ---
**Author:** ![pulykamell](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pulykamell/32/3166_2.png) [@pulykamell](https://boards.straightdope.com/u/pulykamell)\ **Post date:** [June 23, 2018, 2:02pm UTC](https://boards.straightdope.com/t/what-compounds-make-the-odor-of-urine/816562/8 "2018-06-23T14:02:05Z")
> [@Contemplation](#): > > so this brings us back to Ammonia, which urine does not smell like Concentrated stale urine smells like ammonia to me. My kids will often leave their potties filled with pee without dumping it out or before I get to dump it out, and it definitely smells like ammonia. Even me, if I have a particularly dehydrated yellow to dark yellow pee, I get the ammonia whiff, too. ---
**Author:** ![Isilder](https://avatars.discourse-cdn.com/v4/letter/i/cc9497/32.png) [@Isilder](https://boards.straightdope.com/u/Isilder)\ **Post date:** [June 23, 2018, 2:16pm UTC](https://boards.straightdope.com/t/what-compounds-make-the-odor-of-urine/816562/9 "2018-06-23T14:16:47Z")
Urine can also smell of the food eaten or drink drunk. Coffee and Asparagus has a strong smell come out in the urine. Take some urine and remove all the water - Urea is only around 50% of the substances left over. Normal substances found include… Urobilin exists at a high enouch concrentration to make urine yellow, and has the structure of an ester… OOH’s hanging off a long chain… Enzymes (from bacteria in the bladder… there’s some in there !! ) might break it down a bit. The ester structure molecules from it probably smell strongly relative to their concentration. Indoxyl exists at a high enough concentration to dye urine purple if the bacteria ferments it in the right conditions. This has the structure of benzene ring plus another ring, and sulphate as well. So it may be this that provides a sour sulfur smell, sulfur compounds being relatively strong in smell. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [June 23, 2018, 3:18pm UTC](https://boards.straightdope.com/t/what-compounds-make-the-odor-of-urine/816562/10 "2018-06-23T15:18:46Z")
Great stuff here: **[Composition And Concentrative Properties Of Human Urine](https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19710023044.pdf)** NASA-approved! ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [June 24, 2018, 12:22am UTC](https://boards.straightdope.com/t/what-compounds-make-the-odor-of-urine/816562/11 "2018-06-24T00:22:20Z")
Bump. Just realized that, although cite above has good stuff, not OP specific. Sorry about that.