How Long Does Protein Powder Last After Opening?

Protein powder is a common ingredient in many kitchens, but people often wonder if protein powder expires. The short answer is yes — protein powder can expire and lose potency over time. That being said, if you use it before the date on the container and store it properly, your protein powder will likely retain its potency and stay fresh.

There's been some talk that protein powder that has been opened begins to lose protein content and potency immediately, but this isn't actually the case. Most protein powder products will have a "use-by" or "best-if-used-by" date on the packaging, which tells you how long the product is guaranteed to last in terms of freshness, potency and taste as long as it's stored in a proper environment. Normal storage conditions for foods like protein powder are considered to be 70 degrees Fahrenheit and 35 percent humidity, per May 2005 research in the​ Journal of Dairy Science​.

A food that you can be stored safely at room temperature is called shelf-stable, according to the USDA. Other than infant formula and some baby food, federal regulations do not require companies to print a use-by, sell-by, or best-if-used-by date on their product. That said, some states do require the dating of some foods.

The expiration date of your protein powder will also depend on what is in it. Many protein powders are made with preservatives that help extend their shelf life. The researchers in the ​Journal of Dairy Science​ study found that whey protein powder had a shelf life of more than 12 months under harsh conditions (high heat and humidity), and up to 19 months in normal storage conditions. That being said, the protein powder used for the experiment did not contain the preservatives that are typically found in these products, such as lecithin, maltodextrin and salt, which may extend the shelf life of protein powder even further.

Products with a use-by date may still be safe after that date has passed, but they may not be of acceptable quality (for instance, the taste or texture of your protein powder might change), according to the USDA. So before you stock up on out-of-date protein powders at a sale, make sure you check the packaging for a date on the label.

Store protein powder in a cool, dry and dark place. Dried foods like protein powder are best stored at cooler temperatures around 70 F or lower, according to USA Emergency Supply. Store your protein powder in a cabinet away from any heat sources, such as sunlight or the stove, or keep it in the refrigerator so that the temperature stays consistent.

To help preserve the quality, always store protein powder in the container that it comes in. Reseal the container tightly after each use to prevent moisture from getting into the powder. USA Emergency Supply says it is especially important to keep moisture away from dried foods during storage.

Make sure to keep the scoop in the container dry, too, and don't use a wet measuring cup for your protein powder. If you feel the need to wash the scoop in your protein powder, make sure it is dry before you put it back into the container. Water will make the powder clump and can cause bacteria to grow.

One way to know if expired whey protein is still good is to let your senses guide you. If it smells rancid, moldy or just plain foul, consider getting rid of the powder. Also, if it tastes different and it's past the expiration or use-by date, you may want to think twice about adding it to your smoothie.

In general, protein powder is considered safe, according to the Mayo Clinic. But again, because protein powder is a dietary supplement, marketing claims for safety or effectiveness of these products aren't federally regulated.

In September 2018, Harvard Health Publishing reported on a paper from the Clean Label Project that discussed toxins found in protein powder. Based on the research they conducted, the group found that several protein powders were hiding heavy metals, pesticides and other contaminants.

These examples reinforce the need to be cautious when you're selecting the best protein powder. This means reading everything on the product label before using it and paying attention to the smell, taste and texture of it.

If you have any questions or concerns, it's always a good idea to talk to your doctor prior to using any dietary supplement, especially if you have an existing health condition, dairy allergy or you're on medication.