I'm intending on traveling to the US for ~85 days1 for work (with, yes, a bit of a holiday). I'm intending on using an ESTA for this.
As I have a (relatively rare) long-term respiratory problem, I use a preventer inhaler on a daily basis and would need to take these with me. I'm aware that this is explicitly allowed, rather my question is about the amount I'm intending on bringing.
Normally, when I get my prescription, it comes with two inhalers, each with 50 days worth of doses (so, 100 days in total). It's immediately obvious that a single inhaler won't be enough for an 85 day trip.
However, there's a further complication in that I've been told to double my dose if necessary (without consulting with any medical professional, although I've never had to do this for more than a few days when I get a cold or flu), in which case, to make myself feel comfortable travelling abroad in the middle of a coronavirus epidemic, ideally, I'd like to bring 4 inhalers with me. This is technically 200 days of medication. This isn't written on the prescription but I do have a consultant's note saying I can increase my dosage of my own free will (if I need to).
The FDA issues advice2 that [emphasis mine]
In general, you should have with you a valid prescription or doctor’s note—written in English—to bring medication to the U.S. The medication should be in its original container with the doctor’s instructions printed on the bottle. If you don’t have the original container, bring a copy of your prescription or a letter from your doctor explaining your condition and why you need this medication. Travel with no more than you need for your personal use during your stay. A rule of thumb: Bring no more than a 90-day supply of medication.
So, I'm not sure what I can and can't do here - I could bring 4 inhalers (technically 200 days worth of medication) and hope it's OK (would it be?), bring 2 inhalers (100 days worth) and hope that's OK (which I still don't know), or bring a single inhaler. I'd rather not bring a single inhaler, as I'd need to somehow get another either on prescription in the US or posted to the US, neither of which I'm comfortable with doing as I don't know how difficult this would be. Living without an inhaler for a month isn't an option.
So, my question is: Given the above circumstances, would it be acceptable/allowed to bring 4 inhalers/technically 200 days of medication to the US? If not, would it be acceptable to bring 2 inhalers/100 days of medication? If I can't bring 4 or even 2 inhalers, what would be my best option to get more preventer inhalers while in the US?
I'm aware the answer may very well be that 'I need permission', in which case, I'd like to know who or what to ask for this sort of permission.
1 before people start giving advice about Covid-19, I'm aware this is a thing and I might have to cancel the trip
2 similar advice can also be found in pdf form