It was only by chance I discovered a potential link between Metronidazole and Vaping, so I thought it was worth sharing as a reminder to check any prescription medicine for potential interactions with eliquid ingredients. As a relatively new technology, many healthcare professionals aren’t necessarily aware they might need to warn vapers of any potential risks.
The issue came to light after a recent visit to my dentist. I’d been prescribed a short course of metronidazole and warned strongly to avoid alcohol. The reaction between the two is strong enough that you’re advised to even stay away from mouthwashes and cough remedies that contain alcohol. And to stick clear of it for 48 hours after your course of treatment has ended to allow the antibiotic to clear your system. Which is a bit depressing when it coincides with a Bank Holiday weekend in the UK, but fair enough.
What I didn’t know until I happened to check online is that there’s also a potentially similar effect between metronidazole and propylene glycol. Which is a big ingredient in vaping liquids, sometimes along with ethanol.
Uh-oh.
Most of the reports were via vaping forums. But there is also medical information regarding the interaction between metronidazole and propylene glycol. For example, the antibiotic is often supplied under the tradename Flagyl by Pfizer. And they supply some information suggesting propylene glycol carries the same risks as consuming alcohol.
Of course propylene glycol is found in lots of places, including alcohol-free mouthwash, for example. So that’s handy.
And further research only gets more complicated.
I’m not a doctor or medical professional. I’m also not a scientist. So the summary of the following is to simply do your own research and have that alongside the best advice from qualified medical sources (your doctor, dentist, pharmacist etc).
But it appears that the link between metronidazole and alcohol has varying effects, and some exceptions. So it might be that there’s a genetic or other reason why it’s potentially terrible for some people, and yet others can apparently drink without incident. Either way, you don’t really want to use yourself as a test subject.
And as the risk for propylene glycol appears to come from the same process as alcohol, in that metronidazole has an effect on the body metabolising it, then it’s potentially the case that not every vaper would experience the same level of effects.
There’s also more complications, in that the consumption of PG will vary between eating/drinking it, and how much is actually absorbed whilst vaping, the amount in your choice of liquid, and how regularly you vape during the day etc.
I spoke to my dental practice, who weren’t aware propylene glycol was a potential issue present in vaping liquid. I talked to my pharmacist who suggested quitting vaping for 24 hours before starting the course of metronidazole. And I chatted with a few people online, including some health professionals who happen to be friends.
In the end, I picked up a few packs of the tiny nicotine lozenges at the lowest strength available (After getting down to 3mg vape liquid, I don’t want to build up my nicotine addiction again). And then tried to vape as little as possible for 24 hours while using the lozenges.
I only had a 3 day course of metronidazole, so figured the build-up of propylene glycol shouldn’t be too bad. So I simply used lozenges as much as possible, and had a very occasional vape when the psychological addiction was really getting to me. On the first day I had approximately 10 inhales (compared to probably 10 an hour normally!), and no ill effects. By the third day, I was up to around 30 inhales, and still feeling fine. The lozenges were a bit of a hassle, but interestingly they felt a lot easier and more effective than when I tried using them to quit smoking directly.
The TL:DR Advice:
None of this is meant to be advice for anything relating to consuming propylene glycol, alcogol or vaping whilst on metanidazole or any other prescription medication.
The only advice I would say is that if you regularly vape, it’s worth checking for any possible interactions with anything you’re currently taking or prescribed in the future. As even if your doctor or dentist knows you vape (as mine did), they may not know what ingredients it involves. And then you can raise it as needed, do some research, and make the best decisions to minimise the risks and side effects.
Photo by JOSHUA COLEMAN on Unsplash
Update: April 2019:
When you do accidentally mix Metronidazole and Vaping:
Somehow I ended up conducting an accidental experiment on myself when I was recently prescribed Metronidazole for a different illness. Even after writing this blog post and thinking the name sounded familiar, I didn’t quite make the connection.
On the plus side, I can confirm in my individual circumstances that a week of Metronidazole whilst vaping my usual amount did cause significant stomache upsets and pain, along with some disruption to my digestive system. But once the course of antibiotics ended, things rapidly returned to normal.
So I’d definitely recommend asking your doctor/dentist about alternatives, or avoiding vaping whilst taking Metronidazole.
Came across this article when I was prescribed Flaygl (Metronidazole) for an infection. I vape regularly, but not all day. I try to cut back by only using it a bit in the morning before work, and then in the evening a bit. Used to be heavy into it, building coils for drippers, always had a new mod, always had atleast 2 vapes. This was for 2 years.
The first dose – nothing. I tried to vape a bit less because I noticed the pamphlet I got said it should not be mixed with PG… immediately I was like WHAT . But read some stuff online… found that some people had no effects so I decided to just be cautious.
Second day…. totally fine. Again, tried to reduce (I’d say normally I’d have 10 puffs in the morning, 20-40 at night. I was trying to go for 5 in the morning, 10 at night.)
Third day, fine in the day time. Came home from work, was relaxing, had a bit of vape will making dinner… took my pills as usual, sat down to watch a show later and took a hit and oh. My. God.
I have never been so scared in my life.
I was sitting on the couch and my heart started pounding in my ears. I immediately felt like I was going to throw up. The TV was moving in slow motion and the room was spinning. I went and had a shower. My stomach hurt so badly, I felt so scared, I can’t even explain. I got out of the shower, went to lay in bed. Almost lost my balance in those few steps. I thought “if I can’t sleep because I feel so bad, I’ll call an ambulance.” I was having hot flashes, and then shivering uncontrollably. Felt sick, but finally calmed my heart rate and fell asleep, I woke up almost every hour, but felt completely better by the morning.
No vape since then. It’s very hard, I’m on day 6/7 of the meds, but as you mentioned to be safe and wait 2 more day’s.
Yesterday I thought “it’s probably because I was vaping too much, so I’ll just have a small puff and see what happens.” Did it, instantly felt my heart rate quicken again and the room spin, but it only lasted 15 or so minutes. I think what happened is because the medicine needs to be at a constant amount in your bloodstream that I just didn’t have as much and finally I had taken enough medicine to push it over the edge and basically I poisoned myself.
PLEASE be aware people. I found very little info on this, I just want to share my story of “I chanced it and had a horrible time.”
I do mean to scare you, because if you decide to chance it (I don’t blame you, I did) and feel your heart rate quicken, the room spin, anything… have someone you can call. I couldn’t have driven myself to the hospital (which is about 5 blocks away), without causing an accident.
TLDR;
I chanced it and vaped for 2 days on this medication and then out of nowhere had extreme side effects and almost had to call 911 on myself.
Hi,
Thanks for commenting and sorry to hear you had such worrying side effects. Hopefully someone else might see your warning before they mix vaping and Metronidazole (or other medicine with a similar reaction to propyl glycol).
If I’m ever prescribed another course, I’ll definitely be putting up with nicotine tablets at a low strength to subsitute for vaping (or avoiding vaping entirely) while the course runs and for a day or two after to let the drugs leave my system…
Thanks again for sharing and helping to get the word out about something that few medical professionals seem to be aware of (I’ve contacted both my dentist and doctor since it occurred to explain the potential risks and ask them to enquire about vaping if they prescribe it to someone)…
Dan
I’m at the end of 7 day treatment with metronidazole and I’ve been vaping a lot the whole because I didn’t know about the apparent problem with PG. I feel fine and have done for the entire time.
Glad to hear it didn’t affect you – it seems that some people aren’t affected, some get mild issues as I did, and others tend to get a more severe reaction…
Thanks for sharing. I just got Rxed this med and read the basic Rx info sheet then googled for more in depth info, since medication papers are written at a 6th grade reading level with very general statements. This site was the first result of the term “vaping propylene glycol and metronidazole” and I’m grateful to read a comment by someone who vaped in a way I probably would have. Guess I’m quitting for the next 17 days.. This sucks. I don’t like sublingual nicotine, it makes my throat feel tight, but I guess I’ll utilize it if I’m strongly urged to vape. Maybe it’ll be good for me in the long run, who knows.
Hi – thanks for the comment, and happy that I might have helped. Hope the next 17 days aren’t too bad for you!
Thank you so much for the information, it saved me a lot of pain during my course of metronidazole. I tried to vape a little on the first day but it will have me a pounding headache and stomach cramps.
Yesterday was my last day of meds, 2 more to go until I can vape again.
No problem, and thanks so much for letting me know it helped – if I can save anyone from pain or worse, then I’m happy…
Thank you for the warning and for sharing your experience! I have been super depressed all day which is not normal for me so i looked up the side affects of metronozindole and found out about the link to PG. i am a regular vaper and I immediately realized i could be putting myself in danger. I’ve been on the medication for 2 days. I decided to take a couple more puffs and put it away for the night and instead chew some Nicorette. Well, that last puff made my heart start pounding! Luckily it returned to normal within about a minute but i will take that as my warning and wanted to make other people aware.
No problem, and just glad I could help!
Luckily I had some of those small nicotine tablets sat in a cupboard when I realised that PG and Metronidazole don’t mix…
I’m not a chemist or medical professional, but I did think recently that perhaps it will apply to any antibiotic which has warnings about alcohol as well (as a rule of thumb), but I need some time to research this… It might make sense, as most antibiotics will be fine (I’m vaping whilst on a course of flucloxacillin right now without any issues)…
But hopefully more people will know to check for potential interactions with any medication.
So I see the consensus is that PG and Metronidazole don’t mix because of adverse side effects… but that’s not exactly the problem I’m having. I’ve been vaping and have had the same recurring infection four times now. Each time I take Metronidazole, the infection doesn’t go away. I’m starting my fourth round of medication now. I haven’t had any problems with vaping and taking the medication at the same time, however, because the infection won’t go away, I wonder if PG makes Metronidazole ineffective? My prescription bottle says to avoid products with propylene glycol during the course of treatment and “for some time after the last dose.” Whatever that means… how long is “some time”? Each time I’ve taken Metronidazole, I’ve cut down on vaping and even quit vaping altogether for different lengths of time, and I’m still not getting better.
I’m not a doctor or chemist, so I can only go by what I’ve experienced, and researching trusted sources on the internet. Alcohol and PG can apparently limit the effect of Metronidazole and increase side effects, so it’s possible that it may make it less effective. It’s recommended you stop vaping or eating/drinking anything with propyl glycol in (e.g. mouthwash) for a couple of days before starting your course of Metronidazole so the PG can leave your system, and you stay away for a couple of days after the last dose (again, so the Metranidazole can leave your system before you start taking PG in again)….
One option is to ask for alternative antiobiotics. I know in the past when I took anitbiotics longterm that after a while I was switched between different ones to try and find the most effective for me (and I had an allergic reaction to one specific antibiotic, but have never experienced the same thing with any others). With the recent infection that required Metronidazole, I mentioned stomache pains to my doctor and asked about alternatives, and I was prescribed something else (unfortunately I can’t remember the name) which worked, and didn’t have any interaction with PG, so I could happily keep vaping… The interactions between antiobiotics and alcohol or PG are only for specific drugs, not every antibiotic…
If you’re getting a recurring infection Metronidazole isn’t solving, I’d definitely suggest asking your doctor whether an alternative might be more effective…
Not sure if our story is related but sharing. Husband was put on metronidazole, and vaper. First couple of doses no issues, then 3rd dose at night something happened. Within 5 minutes he started getting dizzy, slightly nauseous, had a pain in his throat then couldn’t swallow. This lasted maybe 10 minutes and then could swallow again. The pain let up in his throat, but was still there. Not sure if it was the pg or what, just wanted to share.
Sorry to hear that, and certainly sounds likely (disclaimer – I’m not a medical professional)… I’d definitely suggest either vaping liquid with no PG if it’s available, or switching to other nicotine replacement products until the Metronidazole course has been finished…
The other option is to ask for an alternative medication from your doctor – I know in the past I was able to get alternatives for some conditions when I mentioned Metronidazole had caused stomache issues (I didn’t go into detail about vaping because I’ve had limited success talking to doctors and nurses about it in the past)…
I was put on a two week regimen of multiple antibiotics that includes one week of metronidazole 500mg BID. Guess it’s partially my fault, because I told my doctor that I smoke, not vape. Anyway, I am 4 days along and have 3 days to go. I had symptoms of fatigue, face flushing, difficulty swallowing, and a fast heartbeat when performing light tasks.
I am going to stop vaping for the rest of my metro course, and for three days after. Also, I’ll call a pharmacist in the morning.
Thank you for your blog post. I suffer from health anxiety and a research study I read about someone developing EVALI who was vaping while taking metro definitely scared me. I wish I knew. Logically (and mostly hopefully) I feel like I will be fine.
Thank you for your blog post. Your anecdotal story also helped calm me down quite a bit.
Hi Alex,
Sorry to hear you haven’t been well, and I’m just glad sharing my info helped. From the little research I’ve done (And importantly, I’m not a doctor or medical professional – my knowledge stopped with a biology A level), the side effects you’re experiencing are the most common.
So I’m really glad it’s helped you to stay calm. And pausing vaping (I tend to switch to nicotine tablets) will definitely help, although it might take a little while for the PG to leave your system… It’s worth mentioning PG is also found in other common household items like mouthwash (and definitely avoid any alcohol – that really isn’t good on metronidazole).
Evali was linked to the use of vitamin E in vape juice which often contained THC (the chemical in cannabis which gets you high), so I haven’t seen or found a link to it occurring after vaping whilst taking metronidazole (I’m not a doctor or medical professional, just a writer/journalist who enjoys researching this stuff for work and pleasure). So if you’re buying reputable liquid from a good brand, it shouldn’t be a worry – although longterm studies of vaping don’t exist because it’s not been around long enough, most health bodies are confident enough to recommend it as a much better alternative to smoking etc.
And it’s not your fault. Although you should have mentioned vaping to your doctor, the majority aren’t really familiar with vaping, and don’t realise it contains PG. After my incidents, I’ve made a point of calling and explaining to the doctor and dentist that it’s something they need to know/ask about, but I don’t know if they’ve put that into practice.
So stay calm and relaxed (I know it can be hard if you’re anxious), pause vaping until 2-3 days after the Metro course ends, and if your symptoms do get worse, don’t hesitate to phone for a doctor or medical help. It’s always better to be safe than sorry.
I’m aware this thread is fairly old, but it was a top hit searching for interactions between vaping and Flagyl so I think it’s worth noting that you can purchase vape juice that is all vegetable glycerin with no propylene glycol. I’m about to start a course of metro so that’s what I plan to do. Hope this helps.
Good tip – although I’ve read that because VG juice is a lot thicker it can clog up coils, and won’t work with some vape tanks. I know Nautilus tanks won’t deal well with VG eliquids (I tend to use them a lot with various Aspire mods, and usually prefer MTL vaping, so I haven’t sorted out a kit for VG vaping… But I might think about it in case I need to take metronidazole again…)
Cheers for the recommendation!
Hey Dan!
I just took my first dose of Metronidazole and didn’t realize until AFTER that it can interact with PG. I am a long term vaper. I have vaped for probably over three years but luckily have lessened my percentage from 5.5% to 3.5%. I panicked when I first read about the possible side effects. I called my pharmacist and even poison control and they said there wasn’t enough research on the mixture of Vape PG to really tell me anything. So that’s what lead me here! I’m a pretty small woman, only 84 pounds. I’m hoping my first dose of Metro won’t interact horribly and I will try and cut my vaping down as much as possible. Thanks so much for posting though!!
Hi,
Thanks for the comment, and try not to panic – there’s a risk of issues, but it’s not guaranteed. For me, I was lucky and just felt strangely sick and unwell until I realised what was causing the problem, and some people don’t encounter any problems at all. But there is the potential for more serious side effects, which is why I wanted to share what I’d discovered, so I’m glad to hear it’s helping people.
And the medical services in the UK are in a similar position when it comes to highlighting potential issues with medication if you’re a vaper – fortunately as PG is in so many other products, it should be listed on the information for any medication.
Depends how long your course of Metronidazole is, but in my case, I switched to nicotine tablets for a few days and started feeling better almost straight away… I was glad when the course was over, and I was able to get back to vaping, and since then, I’ve always enquired if there’s an alternative treatment that’s as effective (I just mention I felt unwell on Metronidazole). There’s often other prescriptions available if you enquire, and cutting out vaping is going to be too challenging when you’re already feeling unwell.
Dan
I found this article because I’m pretty sure I poisoned myself and never knew it.
I was prescribed metro and other antibiotics last Thursday. I’m a vaper. When I was given the metro I was told to stay away from alcohol. On the bottle it says check all food source to find any hidden source of alcohol. Ok cool.
I continued to vape and take my meds because I was ignorant.
Two days ago my face starts burning snd I develop red skin. Feel like crap but I didn’t think anything of it (I struggle with acne and has used a face peal the day before)
Well yesterday my face was red and on fire and I noticed my entire body turned red and purple. Head hurt, light headed, eyes would blue, hard to get a full breath just feel generally bad. I did a google search of sideaffects and saw PG was something to avoid. Then I race for my vape juice and there it is PG. My doctor said to go to the e.r.
I thought I was dying. They shot me with benadryl and steroids and I’m home now but still struggling.. still light headed, fast heart rate etc… hope it goes away soon.
Fun fact even your toothpast has alcohol so there’s no telling how many things I was poisoning myself with because I was made unaware of what was safe and unsafe.
So… if there is another antibiotic you can take I would go the other route. Whether you vape or not there is no way to know what products that contain alcohol or variations of that will give you a reaction. Just be careful.
I just got prescribed metrogyl 400 (metronidazole 400mg) from going to the hospital last night and I had taken one whilst there and then one this morning and tonight as per prescribed. I was only warned to not drink alcohol and the bottle only has a warning to not drink alcohol. I wasn’t given a leaflet with an information on the drugs and the pharmacist, when I told them I have never taken them before, just told me when to take them and how many and to not drink alcohol. I went down a rabbit hole of research to find out what medication I can take with metronidazole and found a lot of articles and websites saying not to have pg while on it and stumbled upon this blog. I am a vaper and thought I’m pretty sure that’s in most vapes so I googled the one I have and yep it’s in there. So I then googled my exact medication to see if there was an information leaflet on it to see if maybe it would say on there if I shouldn’t mix pg with this specific medication and I found one and it didn’t mention anything. I’m not sure if it’s ok to still vape or not cause I really dislike the nicotine alternatives. Seemingly so as no side effects so far and the leaflet for my specific medication of metronidazole didn’t say anything about not having pg but I’m not sure.
I’m definitely not medically trained in any way, so I’d always recommend speaking to a doctor/pharmacist if you’re uncertain about anything.
Having said that, I’d personally switch to either VG-only liquid or used an alternative nicotine/nicotine cessation method assuming you’re not being prescribed Metrogyl indefinitely. It’s a hassle, but the potential risks of PG and Metronidazole can be very serious. And even pages like the NGS one on Metronidazole don’t mention PG (https://www.nhs.uk/medicines/metronidazole/about-metronidazole/), which is one of the reasons I originally wrote about it (having felt unwell and spotted it buried in the information leaflet). I’m still a little surprised it hasn’t been picked up by more official medical organisations and websites since then.
Most doctors, and in my case, dentists, don’t know about the potential issue either, so I tell them that Metronidazole caused me stomach issues, so I’d rather take an alternative if there’s one available.
It’s been a while since I took it and continued vaping, but if I remember correctly, I started feeling unwell after 2-3 days of mixing Metronidazole and frequent vaping. Basically, the PG isn’t metabolised as effecively while you’re on metronidazole and starts to build up over time.
And if you do start to feel any potential side effects, seek medical help straight away. In some cases, you might have to go straight to A&E/Emergency.