Once you open a container of protein powder, how long does it stay good for? I need to get back to basics and plan on starting having a protein drink for breakfast, but not sure if I should use the powder that's open or buy new. And no, I'm not sure how long it's been open for. Just don't know if they're shelf stable or if there's an expiration on it.

They do have an expiration on them, somewhere.

Unless it is really out of date, or has been stored in a very hot enviornment , I would think it would probably be ok. Lots of food items are good for a little bit after their exp date, provided they were stored ok etc. They don't neccasarily go "bad" all at once or anything, they may instead lose taste quality or some nutritional value as time goes on.

All that said:

If you are in real doubt, throw it out!!!

I would think if there is no visable date, you keep dry,not exposed to temprature extremes it should be stable. I guess I'm a knee- jerk type, I date everything when it's opened, like" new on March 14,2019" This is my health, my digestion, such as it is, so I'm a little cautious.

with perishable items like dairy and meats, I stick to the expiration date. With other things, I don't so much unless they're WAY out of date. I think they legally have to put an expiration date on food items, but many things can last weeks - or even months or years - beyond that. I don't think I'd try protein powder that was *years* out of date, but a couple of months? (or maybe even a few more than that?) - probably yes - unless it smelled funny.

Ive seen expiration dates on water before...ugh!

12 hours ago, Lovin2lose said:

Just don't know if they're shelf stable or if there's an expiration on it.

It depends on the powder, if it's still unopened or not and how it was stored (cool place, warmer place). I consumed plant based protein powders that were some months over the expiration date and they tasted just fine. However, I also had a plant based protein powder that wasn't even over the expiration date but open for quite a while and it was not really powdery anymore. So if in doubt, throw it out.

I found an answer to your question on Livestrong.com, "Protein powder is designed to last, with many brands staying fresh for up to two years past the manufacturing date. Any protein powder you buy will be labeled with an expiration or best if used by date. Using your protein powder after its expiration date is akin to drinking milk after it has expired."