Do you smell ammonia after a workout? Here is why

Do you ever have an ammonia smell that you just can’t find after a workout? This phantom smell was driving me crazy!, so I did a little investigation.

Before I begin I want to add a small disclaimer. I do not claim to be an expert on this subject. I am not a doctor and have no medical background, nor am I a scientist or dietitian. This article is not making any claims or diagnoses and should be read for entertainment and discussion purposes only.

It seems to happen to more than just cyclist. From what I found it happens to runners and weight lifters too. More than likely it happens to most athletes that workout hard or long. I have never experienced this smell after weight training. I have been lifting for years now and I can’t remember ever smelling the aroma of ammonia. Now, I have noticed the aroma during running workouts or races but never thought that much about it. It really wasn’t until last year that I started to notice almost every time I got in the shower after a ride I could smell ammonia. Not always in the shower but most of the time the smell would be strongest when taking a shower.

As I’m putting my thoughts together it seems clear to me that when I notice the smell the most is when I ride routes by my house. When I get home I jump right into the shower because I am hot and sweaty! When I ride by my house I have to say that I push it all the way up to the point where I only have about ¼ mile or less for cooling off. So usually when I get done my heart rate is still pretty high. I will explain more of my thoughts on this later…

I have to say that I started to get a little concerned with this because of the frequency of the smell. I am a firm believer in listening to your body, it usually knows! Once I started being concerned with the odor I asked my wife if she could smell it. I would ask her to smell my face, hair, and I would even breathe in her face… (I know, that sounds kind of funny.) Anyways she could not smell it? I thought something has to be going on and it’s probably not good?

Interestingly enough what you smell is actually ammonia (NH3).[i] Ammonia is a byproduct “of stripping away of the nitrogen molecule from amino acids so the remaining carbon can be converted to glucose. The nitrogen then bonds with hydrogen to form ammonia, a component of urea,”[ii] which usually leaves the body through sweat, urination, defecation and if the concentration is high enough expelled through the breath. Another possible cause of this smell is a high concentration of acetones in the system. This is a result of the chemical reaction of the liver breaking down fat acids for energy. The breakdown of fatty acids creates three ketone bodies, two of which gets used for energy (acetoactic acid; betahydroxybutyric acid) and one (acetone) which is usually excreted from the body as described above.[iii] Acetone has the chemical make-up of a solvent (CH3)2CO, so as you breath this out you may have a “cleaner” smell as well.

Our bodies have a hierarchy of cycles it goes through when using energy. The first source it uses during exercise is carbohydrates that are in the form of glucose in the blood and glycogen found in the muscle and liver. As these stores are depleted the body will start to break down fat cell stores. As intensity increases the body will begin to break down amino acids for quicker energy. This energy source is found in the muscles. People tend to think that these energy sources are turned off and on like a light switch, either all or none and only one switch can be on at a time. Our bodies are amazing and one of the amazing things is the ability to regulate itself. It will use all three of these energy sources at the same time and more of one than the other depending on the need at the time.

While researching for this article I have been training according to Coach Rob’s plan. I had a power test this past weekend. The test was a total of 30 minute with a 30 minute warm up. So a total ride time of one hour. As I was in my last 20 or so minutes of the test I noticed “that smell,” when I checked my heart rate I was around 173-174 bpm, which is around my lactate threshold. This is the first time that I have noticed what my heart rate was during the smelling sensation.  I was in my anaerobic exercise zone!

Now, I know that I have only been able to confirm this one time so far, but I’m going out on a limb and say… that the ammonia smell is affiliated with the anaerobic training zone. So it seems to me if we look at the training zones there we will find the correlations between training zones and the way our body derives its energy. Whether it’s using glycogen stores from the liver or breaking down fat cells for energy. This may not be news to some but for me it is more detailed knowledge about what I enjoy doing… exercising and staying healthy. And finally figuring out where is that smell coming from?

There is so much to say about this subject that I can’t go into it all. This is such an interesting subject that I will look into more deeply in the future. What I find useful is I now have a physical indicator that lets me know when I have hit my LT. Most trained athletes can maintain their LT for about 45 minutes. This can be of use to you especially during Time Trials… am I working hard enough? Obviously, when you are training, being aware of this can be of use as well.

Some other things that may be contributors to the “smell” are dehydration. If you are getting dehydrated the concentrations of either of these processes I have talked about can be perceived sooner and stronger. I have my bike computer set to alert me every ten minute to remind me to drink. Sometimes I forget to drink while riding so I have a little reminder all the time. I would rather drink before I get thirsty!

If you have insufficient carbohydrates in your system and you are training for an hour or more you may encounter the ammonia smell. That is one of the reasons I try to have some carbohydrates about every thirty minute or so when on long training rides lasting more than 1 hour, so as to not hit the wall. Once you hit the wall or “Bonk” you are usually done! (That’s another subject for another time) Or if you are on a starvation diet and losing a lot of weight in a short period of time your body is producing more ketone than normal and you may smell[iv] “the smell… “

So it seems to me that this ammonia smell is not a harmful experience its just letting you know that your body is working and probably pretty hard! Good for you, keep it up and just make sure you have good nutrition and hydration habits and you should be fine!

One side note I did find where smelling ammonia could be a sign of something serious, and that’s if you have type 1 diabetes. If you smell “ammonia” and you have type 1 diabetes see a doctor right away! I didn’t get too far into why but it has something to do with low liver glycogen stores and blood sugar levels. (Apparently not good for a type 1 diabetic)

Until next time,

Anthony Young

You can check these other articles, blogs and book to learn more:

Protein Power copyright 1996, Michael R. Eades, M.D. and Mary Dan Eades, M.D.

[i] Why do I smell ammonia after I work out?, Yahoo answers, Source:;_ylt=A0LEV1GuNfRSr2IAMSRXNyoA;_ylu=X3oDMTEzZTNidmRzBHNlYwNzcgRwb3MDMQRjb2xvA2JmMQR2dGlkA1ZJUDI4Nl8x?qid=20070123055216AAW8A3n

[ii] Acidic smell after cardio exercise, Michelle Matte, March 29, 2011

23 Comments on “Do you smell ammonia after a workout? Here is why”

  1. this is the answer. i worked our real hard for 75 minutes and i started the smell of ammonia and first i though it was the treadmill. I was also fasting and drinking lots of water like 80 ounces in the 75 minutes session.

  2. Yes fasting while exercising can cause this but as the article explains there is a bit more involved. Those that are not fasting can certainly have this issue. It boils down to not having consumed enough fuel (carbohydrates) to keep up with the bodies need for energy. That is the answer.

  3. Thanks for the article, very informative. I’ve always had this smell but mostly after a really fast run before breakfast. So I’d better have a banana tomorrow morning.

  4. Thank you!! I googled this topic because I have been smelling strong amoniia these last three days that I have been cycling at the gym for 60 minutes at my threshold heart rate—and sweating profusely. I sweat a lot . Also, I’ve been eating clean for the past couple of weeks –mostly veggies and protein. So this makes a lot of sense. When I first smelled it I was walking into the women’s locker room at the gym and I asked the woman next to me if she smelled amoniia –she did not. It’s just in my nose–and overwhelming!

  5. Thanks for the comment Rachel.

    I recommend to all of my athletes that work out longer than 45 minutes in the gym to take on carbs. This is usually done by consuming a sports drink mix that includes electrolytes and approx 200 calories in carbs. These mixes more often than not include either Maltodextrin and or Fructose. Easy to make at home! This will keep the ammonia smell away and will go a long way to fueling your training.

  6. Hey, nice article!

    I get that smell after doing a 5 mile run – I didn’t think I was doing it anaerobically though, although I do tend to try and push it a bit towards the end. Also, a comment on the T1 diabetes (I have T1) – I don’t think it’s too much to worry about – most people can tell when they are having a low blood sugar. Also, I think the smell is associated with ketones – a byproduct of fat metabolism. What some people are probably concerned about to do with that, is that when you have T1 diabetes you can go into what’s called Diabetic Ketoacidosis (DKA), where there’s excess ketones in the body to the point that it begins to alter pH, and this can potentially put someone in a coma, or even be fatal. This only occurs in the presence of high blood sugars, though, so shouldn’t be a problem for someone monitoring their sugar levels.

  7. I’ve noticed this smell for years, I cycle for 40 minutes, jump in the shower, and there it is, THAT AMMONIA SMELL IN MY HEAD. It’s always there, but only after cardio, not after any other type of workout. Usually after 20-30 minutes it dissipates.

  8. I have run over 30 marathons, and after just about every long run, which were on Saturdays, I would smell ammonia in the shower. No kidding, I smelled this most Saturdays for the course of a decade and I assumed my wife was cleaning the shower while I was on my long run. I finally commented at what a good job she does cleaning the shower. She looked at me as if I had a third eye on my forehead. Thanks for the real explanation!

  9. Very good, I have read that and just add that I only smell it after 6 miles usually cause that’s my hour or more, very good info

  10. This is very informative! Now I know why I smell ammonia after my workouts. Thank you for sharing this!

  11. Thanks for sharing, I’ve been trying to understand this kind of smell for a long time.

  12. I was so worried it was something serious! I started riding a Peloton and I would smell ammonia after 45 min rides, and especially in the shower. I asked my husband to smell me, and nothing. Apparently it was all in my nose after all! Thank you for this article.

  13. Thanks so much for the post! The smell bothers me for years and finally I get a big relieve from reading your article!

  14. That makes so much sense! I try to avoid carbs and eating in general before competing in tennis matches. I play better on an empty stomach. I have noticed in the last year a strong ammonia smell on my clothes and everything I googled said it might be related to the kidney. Big sigh of relief that this is a normal-dish thing.

  15. Awesome post! Was really starting to wonder why the sudden strong ammonia smell, which disappears almost instantly, then returns… thanks much!

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