Why Your Protein Shaker Smells So Bad and How to Fix It


If you’ve ever made a protein shake, you’ll probably know what I’m talking about. You forget to clean out your shaker for even a day, and you open it to find an awful smell. Why do protein shakers develop such a bad smell?

Protein shakers develop a bad smell because bacteria and mold thrive on the ingredients in protein shakes. The type of plastic used in most protein shakers causes the bacteria to get ingrained into the bottle, making it difficult to remove the smell.

What kind of plastic are protein shakers made out of, how can we prevent the smell and what do we do if we’ve already got the smell in there? Well, I’ll go over all of that below!

What Makes Protein Shakers Smell So Bad?

Protein powder doesn’t really have much of a smell on its own, and it doesn’t really lose its nutritional value over time or become moldy unless it gets water into it.

Mold in a petri dish.
Mold in a petri dish.

Once water gets into it, though, it cultivates an environment in which bacteria and mold thrive. We know that if we leave dishes out, they get gross and moldy. 

After all, we can’t ignore how likely it is for protein shakers to end up forgotten:

  • In a gym locker
  • In the back of a car
  • In your gym bag
  • In the pile of dirty dishes

And in warm, confined spaces, it helps grow microbes even more, which leads to that disgusting puff of rancid air when you open it. 

Aside from how easily forgotten this kind of bottle is, the plastic is the second element behind that smell it gains, and why it can’t just be wiped clean like any other bottle.

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What Kind of Plastic Are Protein Shakers Made Of?

We’re going to have to dip into a little science to understand why they get so funky.

Generally, protein shakers are made of a stiff thermoplastic, such as:

  • High Density Polyethylene (HDPE)
  • Polypropylene (PP)

Essentially, these kinds of plastics are made up of long chains of molecules (known as polymers). These chains rest on top of each other as they build the foundation of the plastic.

Larger molecules, such as water, cannot pass through these chains. Smaller molecules, such as the chemicals released when bacteria decompose your old protein shake, can sneak into the walls of your protein shaker and get stuck there, making them difficult to remove.

These molecules will eventually dissipate on their own, but those smells may linger on long before many people might throw the protein shaker into the recycling bin. 

Can I Get Sick From a Smelly Protein Shaker?

You absolutely can get sick from a smelly protein shaker. Remember, the stink is from the bacteria growing in your old protein shakes, which is generally the same process behind food poisoning.

Man in the gym drinking a protein shake.

Don’t think about it – it’s not worth the risk. Just clean it out properly after it gets smelly.

If you’ve tried everything to clean out your shaker, it might be best to just throw it out and get a new one. It’s not worth it to get sick or deal with a gross smell.

You can also invest in a metal protein shaker, which doesn’t cost much more than a plastic one. Blender Bottle makes a great metal shaker bottle (link to Amazon).Opens in a new tab.

How Do I Prevent My Protein Shaker From Smelling Bad?

There are a few things that you can do to make sure that your protein shaker doesn’t get completely gross – and prevention is always better than a cure. 

So here are the simplest things you can do:

  • Buy a stainless steel protein shaker – as stated, most protein shakes become gross because of the kind of plastic they’re made from. Stainless steel cleans much easier.
  • Moisture is mainly what causes the bacteria to grow, so mix the protein powder immediately before drinking
  • Most shakers have a compartment for protein powder, but if they don’t, then all you have to do is make sure the shaker itself is dry, and keep the powder in the shaker, and fill it with water when you need it.
  • Clean your shaker out as soon as possible after you’re finished drinking. Even rinsing it out with water before a real wash will help prevent bacteria and smells from developing.

How Do I Get Rid of the Smell?

But what if your protein shaker is already stinking? Well, there are a few tips here that could help you if you’re at that stage as well.

The best way to remove a bad smell from a protein shaker is to wash it out with vinegar or baking soda, multiple times if necessary. These chemicals will aid in removing the smells stuck in the plastic of the shaker.

Washing dishes in the sink.
Wash your protein shaker!

If that doesn’t do the job, I’ll break down a few more options for you.

  • Put it in the dishwasher – it might take around two to three spins for really gross protein shakers, but it’s the easiest option which involves the least amount of that smell in your nose. Just add dishwashing soap and hope for the best.
  • If you don’t have a dishwasher, you could always try dish soap with a heavy dosage of hot water. Soak it for fifteen minutes, empty it out, and give it a wash. Again, this might need repeating a few times.
  • You could always try baking soda if you feel like you need something with a bit more kick. Mix with water and leave for about an hour. Then wash out with soapy water.
  • A denture tablet may also do the trick – more hot water, quarter of an hour of soaking, rinse, and repeat as needed.
  • Something else you can add if you want is boiling water and about one or two cups of vinegar for a few hours. Wash out with soapy water.
  • The last thing we can suggest is hot, soapy water, steel wool and some elbow grease. After all, the main source of the smell is a sheen of protein stank, so sometimes a good scrub might be exactly what it needs to get the smell out. 

The Bottom Line

The reason why protein shakers smell so awful is that protein shakes are prime real estate for bacteria to grow and thrive, and because of the types of polymers it is made of, and the ingredients in protein shakes. These smells root into the plastic and keep it smelling bad. 

It could even make you sick if you’re not careful. Preventing it would be easiest, and the best way to do that is not to mix your protein shake until immediately before you plan to drink it and wash it immediately after.

If it already smells, then you can use all sorts of things to try and help including vinegar, dental tablets, and baking soda. 

Additional Sources

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Pete Schenkel

My name is Pete Schenkel, and I've been into weightlifting since I was a teenager. Now, my main focus is growing Powerful Lifting and putting more information out there. In fact, I'm also currently working on becoming a certified personal trainer.

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