We’ve all had an experience or two in which we went to open a gallon of milk or loaf of bread, only to find that it’s gone bad since the last time it was used. Even though it’s necessary to toss food and drinks that have taken a turn, it’s never easy to discard the money they represent, so it’s understandable that people want to keep using products – even those that are well past their expiration date – whenever possible. Given the expense of protein powder and the fact that it’s used with varying degrees of frequency, many people want to know: Does protein powder expire? And if so, can you keep using it anyway? To find out, keep reading as the team at aminoVITAL® – makers of amino acid fitness supplements – discuss this topic and answer all your questions.

Will My Protein Powder Ever Expire?

As with any food product, the protein powder you buy at the store will almost always come with some kind of expiration date stamped on the container. Most of the time, this date will be months or even years down the road, but even so, it’s not uncommon for people to wind up with a tub of half-used protein powder whose expiration date has come and gone.

Whether you stopped working out temporarily and want to get back into your old routine or simply want to get some use out of a product you spent good money on, you’d probably like to know if that date on your protein powder sets a hard limit on when the supplement can be used or is just a suggestion for when it’s at its best. This question can often seem especially urgent given the prevalence of whey protein, which comes from milk – a product renowned for going very bad very quickly.

However, even if your protein powder is derived from whey or casein – the other protein found in milk – it’s not likely to turn sour or start growing any harmful organisms, largely because it’s a dry product. Mold and bacteria tend to thrive in damp environments, especially when they have sugar and other food handy, but the (ideally) moisture-free environment in a tub of protein powder doesn’t support that kind of life, so it won’t expire in the way that other food products would. Plus, these products usually include additives meant to prolong their shelf life, which can easily push their “best by” date even further into the future.

Can You Use Protein Powder After It Has Expired?

Although protein powder may not spoil like milk, time can definitely have an effect on these supplements, and not for the better. Studies1 have shown that the amino acid content of protein powders can diminish over time, with the clearest example being the essential amino acid lysine. At higher temperatures, these powders can also start to sour in less than a year, with the result being a bitter, even rancid product. If you suspect that your protein powder has undergone a change for the worse, check it for lumps, shifts in color, or unpleasant odors, and when it doubt, throw it out.

How to Store Your Protein Powder to Keep It from Expiring

Virtually any time you buy a supplement – whether it’s a protein powder or post-workout amino acid supplement – it’s a good idea to learn how to store it properly, as doing so can help extend its shelf life considerably and save you from having to replace a spoiled product. Generally speaking, you’ll need to consider two different environmental factors: heat and humidity.

The longer a protein powder is stored, the more the ingredients in that powder will start to oxidize, a process that breaks down the powder and causes many of the changes these products experience over time. Heat speeds up the process of oxidation, sometimes significantly, resulting in a product that can smell bad and taste worse. Research2 has also demonstrated that time- and heat-related changes in proteins can change the structure of those molecules and cause them to mix less effectively with whatever fluid you put them in.

As far as moisture is concerned, the priority is keeping water – which is critical to the growth of harmful organisms – out of your protein powder. Luckily, this factor is easier to address as long as you have a container that seals properly, as is the case with most protein powders.

Expiration of Protein Powders vs. Amino Acids

There are many differences between protein powders and amino acid supplements, including the speed at which they take effect and their respective benefits for the physically active among us. One of the more subtle differences is the variation in how these products behave once they expire.

Because amino acid supplements tend to be lower in sugar – a factor in the degradation of a supplement – they don’t experience the same kind of spoiling effect that you sometimes see with protein powders. The Action mid-workout mix from aminoVITAL®, for example, has no sugar at all, so it doesn’t really go bad, per se. Instead, amino acids tend to simply lose their potency as the years pass; while this change may still spur you to replace old supplements, you don’t need to worry as much about the possibility of drinking a rancid fitness supplement by accident.

Try a Lean, Long-Lasting Amino Acid Powder from aminoVITAL®

People consider a wide variety of factors when choosing a fitness supplement, and the expiration of the various options tends to be pretty low on the list. That said, amino acid supplements from aminoVITAL® earn top marks in plenty of other areas as well; learn more about the science behind amino acids by visiting aminoVITAL® online or calling (888) 264-6673 today.


  1. https://pubmed.ncbi.nlm.nih.gov/26778305/
  2. https://pubmed.ncbi.nlm.nih.gov/15540645/

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