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Peak Flow Post Medication

Does anybody know the amount of time you have to wait to do peak flow after medication Please? It's just that if I just wait 10 mins e.g. like when did spirometry it doesn't improve that much but after 20-30 mins it does. Reading on the internet Looks supposed to do straightaway. Mine takes a while to improve not sure if this is right? I don't have a proper diagnosis yet and did spirometry and was normal, and didnt improve that much after 10 mins wait after inhaler but was so illl actually doing the spirometry e.g. cough, dizziness, chest the nurse said I had to see the Dr as she couldn't say that I didn't have asthma after this test. I have bunches of pf over last few weeks that say it does tho but they tested me when had Brown inhaler for 6 weeks and had dose of steroid tabs!!

5 Replies

This is a tricky one as if can depend on the situation as well as the individual...

For me a mild flare up will usually resolve in 10 mins with 2-10 puffs of my inhaler (timer starting after my last puff 😅) so PF returns to normal.

A slightly more severe flare up for me will have mild improvements initially but at 30 mins I’m either starting to feel good (normalish PF) or starting to get worse!

Any more severe than this and I can find it doesn’t really work at all (maybe only a tiny rise in PF for less than 30 mins or further dropping).

Although for me it’s not usually how quickly I respond to it but how long it lasts as it should last for 4 hours without dropping you PF again (like I said I can start to worsen 30 mins after 10+ puffs). I usually check my PF 20-30 mins post vent, but depending on my mood/how my lungs are feeling will go earlier or later (or what I’m doing 😅)

It is also worth mentioning at when using it prophylactically for exercise I was advised 2 puffs at least 20 mins beforehand so it has time to kick in (at least that was what I was told when I was younger!). Plus on the reversibility challenge they usually make you wait at least 15 -20 mins before the retest

Hope that helps x

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I would take it before but if you are only taking it for yourself does it matter, just be consistent.


Me too I doing a peak flow diary for my consultant and have been asked to do it before taking my inhalers.

When I take Ventolin it will take 20 mins for it to be effective. Hope this helps.


You don't want to be checking it too often, but how about checking 5 mins, 10 mins, 20 mins after your inhaler and find out when it reaches its highest point, you know this is where you get your maximum effect then. You'd only need to do it once this way, then once you have your time, always wait that before checking your post medication reading.


Ah thankyou for all the replies it was good reading them x they have said I got asthma even though spirometry normal as increase in peak flow with medication. I have been unwell doing and since spirometry test. I think I'm just one of those funny people with peak flows that are not that bad but with lots of asthma symptoms. I think my best peak flow is prob way above the 430 they say. They increased my Brown today to four twice a day so will have to see if this works better. Fingers crossed!!

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