How Long After Opening Can You Use Protein Powder?

Since there are so many different flavors of protein powders out there, we’re sure you’ll want to try as many of them as you can.

However, the issue is that now you have a bunch of protein powder stashed away that you may have only used once or twice and now you’re worried about whether or not they’re still good. 

When stored under normal conditions, whey protein powder is good for nine to nineteen months. These normal conditions are defined as 70℉ and 35% humidity. If the protein powder contains additives, the shelf life is then extended for up to two years. Casein protein powders have a shorter lifespan of three to six months once opened. Protein powders that don’t contain milk can last eight to twelve months after their expiry once opened. 

In this article, we’re going to fill you in on everything you need to know about your protein powder and how long it will last under certain conditions. Additionally, we’ll fill you in on how to properly store it to ensure optimal longevity. 

How Long Does Protein Powder Last?

A protein powder that’s milk-based can last upwards of nineteen months when opened and Casein powder can last three to six months once opened.

Plant-based protein powders have a longer shelf life of eight to twelve months after expiry once opened. If the protein powder contains additives such as maltodextrin and lecithin, it can increase the shelf life by up to two years.

A protein powder that hasn’t been opened can last upwards of two years or more depending on the conditions in which it’s stored. 

Does Protein Powder Expire?

Yes, protein powder can expire and go bad, but not as quickly as other food products. You can slow the expiry process by ensuring the lid on your protein powder is tightly closed.

If it’s in a bag, you can squeeze out all the air without pushing the powder out of the top and then completely seal the opening.

You don’t want to leave the bag or the tub opened too long because the heat and moisture from the room it is in can start to damage the contents within the container.  

How Long Is Homemade Protein Powder Good For?

Homemade protein powder is essentially made up of the same ingredients as store-bought protein powder is, but without the fancy additives. You would follow the same guidelines as store-bought protein powder that has been opened.

If it’s plant-based, you can get nine to nineteen months out of it, but if it’s milk-based, you will only get 3-5 months out of it before it expires. 

One study showed during an accelerated shelf-life test, whey protein powder has a shelf life is more than twelve months and even all the way to nineteen months under normal conditions.

This test measures and estimates the stability of a product by storing it under stressful conditions. In another study, researchers found that whey protein had a shelf life of just nine months when stored at 95℉ but eighteen months when stored at 70℉ with 45-65% humidity.

Either way, most protein powders on the market have additives that increase their shelf life allowing them to last two years or more. 

What’s The Best Way To Store Protein Powder?

Protein powder should be stored in a cool, dark, dry environment such as in a pantry or kitchen cabinet. Once it’s opened, it should be stored in an airtight container to prevent moisture, dirt, and bacteria from reaching it.

Fortunately, protein powder generally comes in a plastic tub that’s easy to open and re-seal. If it comes in a packet, it would be better to transfer it to an airtight Tupperware container. 

The best environment to store opened and unopened protein powder is at 70℉ at 35% humidity. You may not be able to control the humidity in your home all of the time, which is okay.

Your protein powder won’t expire at a fast rate if the humidity is a little off. 

Can Storing It In The Fridge Extend Its Shelf Life?

You should never store protein powder in the fridge as it may expire before the date. This is because the sudden change in temperature from hot to cold can cause condensation and will spoil your protein powder quickly. 

Can Expired Protein Powder Make You Sick?

No, it will not make you sick. However, the protein content can decline, reducing its overall nutritional value. This is because the lysine in protein powders will react with sugars and break down over time.

Since lysine helps build muscle, a protein powder with little to no lysine won’t be very effective. The FDA doesn’t require supplement brands to include an expiration date on their products, but most do anyway.

Consuming protein powder after its expiration date is safe as long as it has been stored properly. If it’s passed the expiration date, the quality won’t be the best, but it also won’t make you sick. 

How To Tell Your Protein Powder Is Bad

There are actually four simple ways to tell if your protein powder has spoiled. 


One of the best ways to tell if your protein powder has gone bad is to smell it. If you smell a foul/sour odor in your container, then you know your protein powder has expired and it’s time to get rid of it. 

Check The Color

This is kind of tricky since manufacturers sometimes use bleaching agents in their powders to make them look more appealing. However, you will notice that natural protein powders are generally brown/yellow in color.

So if you notice that your protein powder doesn’t look like it should, it’s probably a sign that your powder has gone bad. 


If you notice wet lumps in d indication that your protein powder, this is a solid indication that your protein powder is no longer safe for consumption. This means that there was humidity present and mold has begun to grow. 


When in doubt, taste the powder. We don’t mean taste the powder directly, rather, put it in a drink and see if the taste is different than what you’re used to. It might taste bitter or sour, which is a great indication that the powder is no longer good. 

Plant-Based9-19 months2+ years
Milk-Based3-5 months9-19 months

How Does Adding Protein Powder to Liquid Change It?

When you mix protein powder with liquid, it has to be used within 48 hours once it’s been refrigerated. Most people mix their protein powder into a shake before heading off on their journey.

They then keep it in a container or bag until it’s ready to be consumed. However, if you leave your protein shake in a container in a hot environment, you’re not going to want to drink it. 

Benefits of Protein Powder

Protein is one of the main nutrients needed for building blocks of bone, muscle, and skin. Your body also needs it to produce hormones, enzymes, and other chemicals.

Eating protein-rich foods and using supplements such as protein powder can help people feel fuller for longer. 2017 study showed that those who supplemented with protein powder had reduced body weight and total fat mass in those who were overweight. 

Weight Management

You’ll find that many athletes and gym enthusiasts will drink protein shakes because they think that these drinks will bulk them up.

Research does suggest that protein supplements greatly improve muscle size and strength in healthy adults who take part in resistance exercise training. 

Heavy dumbbells near sports bottle and a bowl of protein powder
Protein powders greatly improve muscle size

Recovery After Exercise

In addition to muscle growth, protein can help repair damaged muscle and tissue. As a result of this, athletes tend to use protein powder to speed up recovery from exercise-induced muscle soreness.

Studies have shown that consuming a protein supplement after exercise can aid recovery by reducing the amount of muscle damage and improving performance and muscle protein synthesis. 

Additional Nutrition

It’s recommended that your daily intake of protein in people aged 19 years and older is 46g for women and 56g for men. Those who find it tough to meet these amounts use protein powder as an easy solution.

Older adults, those with chronic illnesses, weight lifters, and athletes may need to exceed the recommended intake recommendation. 

Types of Protein Powder

There are a few types of protein powder with whey being the most popular and the one that researchers tend to set their sights on for their research. Common types of protein powder include: 

  • Whey: Water-soluble milk protein powder that’s popular among athletes. 
  • Casein: This protein is rich in glutamine which can help speed up muscle recovery after exercise. It’s a dairy product and not suitable for people with milk allergies or vegans. 
  • Soy: This is an excellent alternative to whey or casein for those who cannot consume dairy. 
  • Pea: Pea protein is a great source of arginine and a good alternative to dairy and soy-based proteins. 
  • Hemp: Hemp protein contains essential fatty acids and is a good choice for vegans or those with dairy or soy allergies.


Different types of protein powders
Different types of protein powders

Bottom Line

Protein powders are ideal supplements that are animal or plant-based with an acreage shelf life of nine to nineteen months with a maximum shelf life of two years.

Consuming protein powder shortly after its expiration date is likely safe if there are no immediate signs of spoilage. However, if you notice a rancid smell, clumping, or bitter taste, it’s best to toss your tub and purchase a different one. 

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