Why do I have a Metallic Taste in my Mouth during Strenuous Exercise?

I want to share my personal experience and findings as it relates to tasting metal or blood when you do an intense training session like running, Cross Fit, etc. – just note that I’m not a doctor – so I don’t pretend to offer medical advice, just my experience as a runner and some of the best resources for this condition online.

Now that I’ve made my disclaimer, yesterday I had a nice run with a couple of friends of mine.  Actually, calling it a nice run is somewhat misleading since the run was both completely horrible and awesome at the same time.  I guess that averages out to nice right.

My friends and I went out and ran the Badger Mountain trails in Richland, WA starting from Trailhead Park up to the top then down the Skyline Trail to the parking lot off of N. Dallas Road before turning around and doing it in reverse.

The Badger Mountain trails are not extremely steep but if you are not used to running hills they can certainly put you in a position to overexert yourself.

Yesterday when we ran Badger I think it had been like 6 months since that last time I purposefully ran hills of any kind.  I probably should have spent more time on Badger this year than I have and perhaps the Boston Marathon’s Newton hills might not have kicked my butt as bad as they did.

Anyway, one of the guys I ran with obviously had done more hill training and took off like a rabbit up the side of the mountain headed to the top.  I tucked in behind but I tell you what, it was a rough 1.75 miles to the top.  There was some major league sucking wind going on from my end.

When we all three made it to the top I swear my heart was going to burst out of my chest and flop around on the ground before expiring.  The interesting thing was it totally tasted like I had been sucking on the bumper of a Buick or something because I had a bad taste in my mouth – best described as the taste of metal –  as I stood in the breeze catching my breath.

Have you ever had that experience before where you have a metallic taste in your mouth after a strenuous run? 

I know I have at times in the past when I was not in good of shape and tried to do too much.  I was curious what that was all about so I decided to do a little research yesterday.

I asked a couple of people I knew if they had ever “tasted metal” before during a hard workout.  Some said yes others said no.  Turns out that those who said no often clarified they had “tasted blood” during a hard workout.  Interesting…

I did a little research and you know what it is?  It is actually a mild form of heart failure. 

That sounds super scary but it is actually not that uncommon and is really just a sign that you are exerting yourself beyond what you heart was able to keep up with.

How Your Heart Works

So how does the human heart work anyway?  We all know that the human heat is nothing more than a pump to keep the blood circulating through the body to keep us going.  It is actually pretty interesting how it works.


Blood flows through the heart in one direction, from the atria to the ventricles, and out of the great arteries, or the aorta for example.  Blood is prevented from flowing backwards by the tricuspid, bicuspid, aortic, and pulmonary valves.

The heart acts as a double pump.  The function of the right side of the heart is to collect de-oxygenated blood, in the right atrium, from the body (via superior and inferior vena cavae) and pump it, via the right ventricle, into the lungs (pulmonary circulation) so that carbon dioxide can be dropped off and oxygen picked up (gas exchange).  This happens through the process of diffusion.

The left side collects oxygenated blood from the lungs into the left atrium.  From the left atrium the blood moves to the left ventricle which pumps it out to the body (via the aorta) to bring oxygen to the body.

Heart Underperformance

Typically when you are resting or exercising you are at an equilibrium in that your heart is normally pumping out exactly as  much as it is pumping in.  

This system usually runs very smoothly, resulting in the proper flow of blood.  Nonetheless, if one element of the pump is not performing at full capacity, fluid can accumulate in unwanted places.  If your left ventricle is not able to pump blood out of the heart to the body at the rate the right ventricle pumps it into the lungs, fluid accumulation in the lungs can result. 

This is sometimes referred to as a pulmonary edema.

Why Do I Taste Metal?

Our red blood cells contain hemoglobin, a highly efficient molecule whose purpose is to collect and transport oxygen.  Hemoglobin is carried around in groups connected by a central iron ion (Fe).

When you are overexerting yourself, fluid can accumulate in the lungs where some of the excess red blood cells can accumulate in and be transported to the mouth via phlegm (nasty I know…).  Our tongues carry receptors that respond to iron (Fe) by sending a signal to our brains that we sense as a “metallic taste.”  Whether you taste blood or “metal” it is basically the same mechanism at play.

How Can I Prevent Tasting Blood?

Even though it’s not necessarily a painful experience, having a blood or metal taste in your mouth is certainly gross and a little concerning. 

So how can you guard against this happening next time you work out? 

According to Nordic researchers one way is to simply get your body in better shape. As mentioned from my anecdotal experiences, when you’re not in top shape – this is more likely to occur. As you get into better shape, your blood vessels are better equipped to handle the pressure and you’re less likely to taste blood. 

Whether or not you decide to keep running at that moment and press through the weird taste, that’s up to you. There’s nothing definitive that suggests it’s dangerous to continue – but more than likely it’s in your best interest to take a break and let your body recoup a bit. 

Even though getting in better shape may help, it’s not 100% guaranteed to stop you from experiencing this phenomena. Even elite athletes can get the taste of blood or metal in their throat – so just because you experience it, doesn’t mean you’re necessarily not a fit person. 

How Serious Is This Problem? 

In short, you have a metallic taste in your mouth during strenuous exercise because your heart is unable to keep up with the physical demands you are placing on it.  Is this a sign of really bad things?  Not necessarily.  Particularly is there are no other symptoms of concern.

Our bodies are capable of dealing with this mild form of cardiac underperformance.  You will typically experience relief from the symptoms when you stop exercising and resting for a bit.  By resting a bit you are decreasing the demand on the system and the left ventricle is able to catch up to the demands of the right ventricle.  The fluid is thereby cleared out and red blood cells are no longer accumulating in the lungs.

According to the experts, actual heart failure produces additional symptoms including shortness of breath.  This is accounted for by an even more extreme accumulation of fluid in the lungs than is expected during strenuous exercise.  One could also expect persistent coughing or wheezing, buildup of excess fluids in body tissues (i.e., swelling of feet, ankles, legs, etc.), fatigue, nausea, confusion, impaired thinking and increased heart rate.

If you do not have these sort of symptoms, you probably just over did it a bit on your run so the next time you try to chase someone up the side of a mountain, well just let them go…

Obviously I’m not a doctor, so if your symptoms persist or worsen, you might be wise to go see a medical professional. 

36 thoughts on “Why do I have a Metallic Taste in my Mouth during Strenuous Exercise?”

  1. Over the years, I experienced this phenomenon on numerous occasions. In all instances, it happened when my fitness level was in question and I’d over exerted myself. Cold air temps also seemed to precipitate the event.

    • I just experienced again recently myself when I was doing hill interval repeats. I have to admit that can second your observation that cold weather certainly does not help and well when I have experienced that metallic taste in my mouth it has been when my fitness did not match the load I was putting on my body. I have also noticed that when I jump straight into strenuous exercise with little to no warm up it is pretty much a guarantee. Here is to continue happy, smart running for both of us!

      • Cold air, poor fitness level, and no warm up: check!

        Someone’s car broke down on the side of the road so me and another guy jumped out and helped him push it. Immediately after we finished, I was coughing and I had that metallic taste in my mouth.

        Glad to know I’m not alone and that I didn’t rupture my lungs even if it felt like it 😉

    • You actually make it appear so easy along with your presentation but I find this topic to be really one thing which I think I might by no means understand. It kind of feels too complex and very large for me. I’m looking forward for your next submit, I will try to get the dangle of it!

  2. Thank you for posting this. I’ve had this issue since childhood. We used to run the 600 (I assume 600 meters) during our physical fitness tests. I always came in last and had the taste of blood in my mouth and coughed for about 45 minutes. It still happens if I try to run. I wonder if it is related to my Mitral Valve Prolapse.

    • That is a great question Lauren. I am sorry that you have to deal with mitral valve prolapse and while I am not a doctor I can certainly see the logic behind a correlation there. I hate that you have adverse experiences when you run. I hope that you are able to still get out there and be active within the constraints you have.

    • Lauren,

      I know this is really late, but I hope you see this somehow:


      It is a medical study that mentions the link between mitral valve prolapse & exercise-induced pulmonary edema.

      “In a single case report, an apparently healthy man developed pulmonary edema after exercise [16]. Interestingly, a clinical examination revealed mitral valve prolapsed, and the authors suggest that this structural abnormality likely contributed to the edema formation. There may be a role for unrecognized valve dysfunction in other cases. Indeed, in patients with left ventricular systolic dysfunction, mitral valve dysfunction is associated with increased pulmonary vascular pressure, capillary barrier disruption, and exercise-induced pulmonary edema [17].”

      Best of luck!

  3. This was so helpful to me. I am 17 years old and have ran two half marathons and ran cross country and track for the past three years. This blood taste happens to me usually when I’m out of season. I ran today for the first time during my holiday break and it happened. Thank you so much because it had honestly scared me.

  4. While I’m a very active person and eat well, I am 24 years old, and the alarming thing is that my mother passed away from congestive heart failure at 43 years old, just 2 years ago. We were/are very both stressed individuals and I’m sure her smoking contributed to her death too.

    I just don’t want this to be any more serious than it already looks to me.

  5. Thank you so much for this: I regularly have this happen when I run outside. Being an athlete and having played sports all my life, I wonder though if it only relates to your level of fitness, because the mysterious thing for me is: I don’t have any symptoms like this when I run indoors (on the treadmill) and have much longer stamina.
    Have you ever heard of this?

  6. Thanks for the post! I’ve always had trouble with cardio workouts. I can push myself to do them, but the consequences usually suck. Depending on workout intensity I’ll start wheezing, build up phlegm in my throat, taste that metallic taste and become nauseous. I’ve been told most of this is because I’m not breathing enough/deep enough. My fingers and toes are always cold and sometimes i’ll experience heart palpitations or random high blood pressure (especially if I drink caffeine.. *shudder*).
    Yes, I’ve seen a cardiologist and got a heart ultrasound, tilt table test and some other test but they couldn’t find anything. All the women on my mom’s side have experienced this (acutely during the teen years). I’m 17 now and seem to be continuing the tradition.. My mom thinks we have something called POTS (Postural Orthostatic Tachycardia Symptoms). Postural Orthostatic Tachycardia Symptoms. Apparently it’s extremely hard to diagnose though, but that might explain why my first heart tests came back negative.
    Any advice?

  7. Nice post. I just got back from a run after being out of training and I’d thought I’d look up the mechanism for the blood in mouth taste.
    Thing is- I’m a cardiologist. Whilst I admire your thought process I don’t think you are quite correct. Yes when you are pushing hard your heart is at its maximum capacity. BUT you’d have to work pretty hard and likely have a structural abnormality such as mitral valve prolapse, to get pulmonary oedema. When I see that it my patients they have pink, frothy sputum.
    So what are you describing? My explanation is simply that with max cardiac output the BP is elevated and there is maximum vasodilatation to help with heat dissipation. In the mouth, the small capillaries dilate up and you can taste blood but there isn’t actually any bleeding. It’s a similar mechanism where some people night get nose bleeds if they have fragile capillaries whilst exercising.
    Time for a glass of water.

    • Hi James,
      Can you please answer Gilly’s question below because I have the same issue and I would be interested to hear your take on it if what was said in the article isn’t correct.

  8. Hey James,

    I have a question based on what you just said…why is the taste coming from the lungs then?

    For me at least, the taste is most definitely from the lungs. When I hack up something I can feel it coming up from the bronchials (which hurt like fark during all of this) and up into the back of my throat, and that’s where I get the taste most strongly. Water does not help, and I drank tons today afterwards to re-hydrate.

    Yes, there is some slight taste just breathing heavy, similar to when you have a bad chest cold that’s going south and you can “taste” the bacteria. But nowhere near what it is when the mucus comes up.

    It’s been just around 12 hrs for me and while I’m not as bad as I was earlier, I’m still hacking and you can hear the wheezing/rattling when I breathe.

    I’ve always had this when I over do it, I just over-did it more today than I ever have (bad Gilly). From my reading today, a lot of people seem to have this issue specifically. And of course it’s been found all over in racing animals of various species and breeds.

    /Not trying to be argumentative, just trying to understand what exactly is going on and the mechanism by which it all operates. Cheers! 🙂

  9. Thank you for posting this. I get this quite often when I run the 2.75 mile run I do about 2-3 times a week. I probably would not even run this much, but Uncle Sam demands me to be in better shape and this phenomenon had me worried a bit. The last thing I want to happen is any kind of health issues either now or down the road. I never had this problem in my twenties, but now in my late thirties, it is happening more often.

    Again thanks for the post!

    An out of shape veteran.

  10. I have been reading about particulates in the air that are causing a metallic taste in people’s mouths, including mine. I am not a runner. I can be outside playing with my kids and taste it. I used to think that it was dehydration or that it was related to food I ate or poor oral hygiene but it’s not. It’s related simply to going outside. These are not just any particulates. They are metals. Specifically, barium, aluminum and mercury, among others. Our breathable air is full of it and it has the potential to cause serious health problems.

    • This happens to me whether Im indoor playing hockey or in my basement with heavy cardio. This is definitely not and outdoor thing. Cold environments do perpetuate the problem and it happens only when I over do it, the better shape Im in, the less it happens. I just started Old mans hockey (indoor) and I had the metal taste and was coughing up mucus and wheezing for about 4 days after. Im not saying metal particulates are not in the air, but try over exerting with a mask on, there are no noticeable differences, except the cold air won’t contribute. Careful what you post, some of these symptoms, along with others can be quite serious.

  11. Thank you for clarifying this question! I’m from Brazil i had this same issue and couldn’t find any Web site in Portuguese with a reasonable explanation about it.
    Thank you for your help!

    You are helping runners from all over the world! (:

  12. Hey, thanks for this post! Sports have always been a part of my life. Sports leagues & “after 4” were always fine for me, it was when i would run track &n want that 1st place or ot beat my previous time & over exert myself i would always taste blood or iron in my mouth.. I do remember asking my gym teacher & she said that means my lungs are bleeding stop when that happens and take a break.. &tonight i played hockey for a couple hours &im really not in shape and oh my i had the heart pounding blurry vision short breaths, i puked then once i puked once that wouldn’t stop lol.. took 15 mins tried to play more but just couldnt &cooled off in the shower.. the blood tastes still in my throat & i have eaten brushed my teeth drak multiple beverages.. &im still getting coughing attacks though.. that why i think its to do with the lungs cause i’m still heaving & the blood taste is there.. how ever it could be the first explanation then now as i’m still coughing i may have just irritated my lungs & they bled a little.. a cocktail of sheer greatness…I have no clue really but it seems like your article offers some enlightenment.

  13. Oh yah, as well i wanted to touch on the underlying heart condition may be.. because once i got to around 14 or 15 i started getting these attacks where it would feel like pins are poking my heart all over and the pins go deeper & the pain intensifies as i take deeper breaths.. so ill put my head between my knees &keep taking small breaths till the pain becomes tolerable then breath deeper till i feel (the only way i can articulate this feeling) a popp or bubble go then i can breath normal but with this lingering pain in the heart.. last one of those attacks was two nights ago.. so this may as well be a early warning sign or a greater heart issue in the future.

  14. Oh my god. This has been happening to me since I was a kid. Glad to know what is going on. I always thought it was because I was asthmatic. I guess that probably contributes. I ran today and pushed myself more than I should have (haven’t run in months) and was tasting metal, coughing when I got home, and my fingers were swollen. Guess that means I need to work back up to where I was and not try to start there. Thanks for posting!!

  15. This is exactly what I have been experiencing with an increasing level of concern -EXCEPT that instead of tasting the metal I am definitely SMELLING it… I never noticed this happening before a few months ago. I’m very active, 35 years old and have been very active since I was 22 years old (when I quit smoking).

    Sometimes, in the past, if i would overdo it, I would become nauseous. But this metallic smell is new to me. And you’re all describing it as a taste. I am sure that I SMELL it and it’s really gross. It usually fades within 10 minutes or so of cooling down.

    However – and I can’t explain this either but it helps back up the blood/taste/smell thing… When I got anesthesia for an operation, I remember just before blacking out that I smelled terrible chemicals – and I told the nurse and I heard her say well, actually.. That’s a taste that… And I was out. I know that’s probably not hugely helpful, but it makes sense if the medicine they injected into my bloodstream made me smell something strongly too.

    Hopefully we’re all okay!! 🙂

  16. I am so glad I found this article. I have experienced this phenomenon for the past 30 years. Whenever I’m attempting to train for any sort of distance running, the training sessions that really make me feel pushed end up with a metallic smell coming up from my bronchial passages. This is the first time I have a clear notion that this weird experience is my body saying “PLEASE SLOW DOWN”!

    As I am reaching 50, I am looking for sustainable ways to take care of my body. I am training to run shorter distance runs (5-10K), and I have found that I make the best progress when I keep my intensity to a level below that which triggers the metallic breath. In my case, that is four steps per cycle of breath: left-right on the inhale, left-right on the exhale. When I need to breathe faster than that, I get the metal breath. So, I have opted to lower the intensity of the exercise in order to keep my breathing at a steady cadence.

    Thanks again!

  17. I get this sometimes especially, when I just started exercising, but also when I push really hard. I always assumed it was lactic acid buildup because I would say the taste is vaguely like yogurt for me. It’s not the same as the burn I get when I run at a high pace for a minute or two (800 m run for example) only when I do something anaerobic. When I first started training I was getting it a lot for a few months,. I got it from a lot of things like doing dips, pull-ups, push-ups, hill sprints, or riding my bike really hard, but never from doing something at a more moderate pace like a 5mile run or something. the feeling has kind of gone away lately but I got it yesterday when I was doing my last set of dips and was barely able to come all the way up on the last rep. I haven’t ever found a good explanation for why this happens everyone even doctors says something different on the Internet at least.

  18. James post was right on for me ‘Yes when you are pushing hard your heart is at its maximum capacity. BUT you’d have to work pretty hard and likely have a structural abnormality such as mitral valve prolapse, to get pulmonary oedema. ” Think January in Chicago, Went to treadmill class at lunch, then happy hour, then sprinted for the train. Made the train but my heart was 2 blocks behind. Coughing, nausea, metalic taste, heart palpitations on left side continued during sleep for days. Dang drinks, cold, sprinting and MVP don’t get along. Head of Cardio at NWM actually said my heart performs better during exercise. Ok sure

  19. Hi, i like many of you are experiencing similar symptoms. Last night after a month off of exercising, i went to the gym and just “killed” it on the elliptical. But one i was done, i noticed i had shortness of breathe and pain in my chest i would cough and taste this metallic taste in my mouth. All night i could not take a deep breathe and felt like i hade a weight/pressure on my chest. Today i still had pain in my chest, feeling as if deep breathe would cause stabbing, i felt like somethinh was sitting on my chest, after every cough metallic taste and swollen feet by end of day. I did call my doctor and had a full work up done. Will keep you all posted. Thank you for listening to my story.

  20. I have the same thing and have since I was young . I work out quite regularly and this is occurring more and more . When doing cardio I know my body can physically go harder it’s in my lungs and breathing that cant. I tell myself this is a way to make my lungs stronger is keep working at it lol . Does it get better ?

  21. Thanks for posting. I experience it too, all along i thought it is the taste of lactic acid building up too much on my body during an extra-hard excercise.

  22. Great read! 🙂
    I’m 37 and have ran 8 half marathons and the London marathon.
    For a while now I’ve experienced this taste following some of my longer runs. I usually finish my run, cough a few times and then have the taste. Urghhhhh. But today following a 9 mile trail run it was terrible. Lasted for ages!
    I’m a nurse by profession and was seriously thinking I need to consult one of my medical colleagues! ?
    I feel better knowing it is more common than I thought, but I still may chat with them anyway?
    I’ll keep you posted …

  23. Hi there,
    Firstly thanks very much for this info – I’ve been trying to work out why I taste metal for YEARS – knowing that blood is metallic, I used to believe that perhaps it was my blood going so fast it was leaving some of its ‘metal’ behind in my mouth! Daft, eh!

    This leads to a follow-on question though. For me, the other thing that happens when I overexert myself (which is sadly any time I do anything at all that gets me out of breath) is that my teeth (or gums) hurt.

    Do you think that this is also in some way linked to the mini-heart-failure issue? Right after I stop exercising, within a few seconds as I am still gasping like a fish, my teeth set to throbbing really painfully and it occurs at the same time as the metallic taste. They also subside at the same time, when my heart rate slows right down.

    Do you have any theories about why this gum pain could be happening?

    Thanks, and great article!

    Gillian R.

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