Mold In Your Coffee Cup: How To Remove And Prevent

Being able to take a cup of your favorite brew with you on your journey to work is a luxury many of us appreciate each and every day.

So what happens if you go to your cupboard, pick your favorite coffee mug and see that there is mold around the lid and the bottom?

Does the cup need to be thrown away, or can it be cleaned and used again? Can the mold in there make you sick, and how can you stop this from happening again?

In this article, I will be answering all these questions and more, so keep reading.

mold in coffee cup how to remove

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Why do coffee mugs become moldy?

Mold is not picky as to where it lives, as long as the circumstances are correct, mold will grow pretty much wherever it can, and unfortunately, your favorite coffee cup is no exception to this.

Mold only needs a few things in order to thrive, these are:

  • A source of nutrients
  • A source of moisture
  • An ambient temperature between 60-80 degrees Fahrenheit
  • A lack of natural sunlight

As you can probably see from the list above, a coffee cup left in a rucksack or handbag on Friday, then forgotten about until Sunday will very easily provide everything that mold needs.

It can feed off the minuscule particles of coffee grounds, or any leftover sugar or syrups left in the cup. The moisture comes from any remaining coffee or steam that condensed on the lid, and with the lid left on, there is no danger of sunlight. It has also probably been left in a comfortably warm room of the house all weekend, which gives mold the perfect opportunity to grow.

Can you drink out of a coffee cup that has mold in it?

If we are talking about giving the cup a quick rinse under the tap and then using it again, (or even worse), scraping the mold off and hoping the hot coffee will kill it off, then no, this is certainly not a good idea.

Whilst there are hundreds if not thousands of strains of mold that will cause little to no harm to humans, there are still plenty of strains that can be hazardous if inhaled or ingested.

If a mold feels threatened, it can produce mycotoxins, if these mycotoxins are ingested through drinking coffee out of a moldy coffee cup for example, then gastrointestinal discomfort, headaches, and nausea can result. If the spores are inhaled, then breathlessness is possible, whilst for allergic asthmatics, a full attack is quite possible.

As a result of the potential for harm, it is never advised to simply scrape the mold off a coffee cup or give it a quick rinse. You should take the time to follow the steps below to completely clean your cup to make sure it is safe to use.

How can you tell if it’s mold in your coffee cup?

To determine whether or not you are dealing with mold in your coffee cup or something else entirely, you can look for the following traits.

Mold will usually come in one of several shades, black, blue, green, white, or even orange or red. They will also tend to have a texture that is best described as “fluffy”, “powdery”, “velvety” or sometimes even slimy (depending on the strain). Despite being able to spot these shades and textures, it is still very difficult to tell exactly what strain of mold you are dealing with.

It’s therefore best to always approach mold with caution, as you could well be dealing with a toxic strain. Wearing protective equipment such as a breathing mask, rubber gloves, and eye protection is always advised if you plan to clean or remove it yourself.

How to get mold out of coffee cups

In order to remove mold from a reusable coffee cup, you will need to take the following, simple steps.

  1. Take the coffee cup apart completely
  2. Make a solution of one part white (distilled) vinegar to one part tap water in a spray bottle
  3. Liberally spray the coffee mug (and its rubber seal) in the white vinegar/water solution, and leave for five to ten minutes. The vinegar will kill any mold and its spores.
  4. Wash with warm soapy water to remove any mold and vinegar residue.
  5. Ensure the mug is allowed to dry fully before sorting it away for its next use.

Whilst washing your coffee mug with warm water and detergent may be enough to remove any mold visible to the naked eye, if you want to be completely certain that all the mold is dead, white vinegar is an environmentally friendly and highly effective manner to do so.

If you don’t have any vinegar to spare, or you are worried that it may leave a vinegary aftertaste, you also have the option of using baking powder.

Take your coffee mug apart completely (including removing the rubber seal from the lid). Make a simple solution of baking powder and tap water, and again, using a spray bottle, spray it all over every part of the mug (again, including the rubber seal).

Leave the baking powder solution to do its work for at least 5 minutes. The powder has a PH high enough to kill mold, whilst being completely harmless to humans and being taste and odor free.

Simply wash off any residue from the mug and allow it to dry completely before storing.

How to prevent coffee cups from becoming moldy

It is much easier to ensure your coffee mug does not become moldy in the first place rather than having to clean it when mold does eventually decide to call it home.

Prevention, in this case, is a simple process, as all you need to do is take away everything mold needs to live. Without perfect circumstances, it cannot and will not grow.

In order to stop mold from growing in your coffee mugs, use the following steps:

  1. Make sure your mug is completely clean each after use
  2. Check the rubber seal every few weeks to make sure it is clean and there are no cracks in the rubber
  3. Ensure once the mug is clean that it is completely dry before being stored

Do you need to throw away a coffee cup that had mold in it?

After reading about the potential health hazards caused by accidentally inhaling or ingesting mold and/or its spores, you may think that your coffee mug needs to be thrown away if you find mold growing in it.

This is not always the case, as if only a small amount can be seen, the methods of removal suggested above should suffice in making the mug useable again.

The exception to this rule is if the cup has been infested with mold for a prolonged period of time, (several weeks for example). If this is the case, the mold may have penetrated deep into any crack in the rubber seal and will be significantly harder to remove.

If this is the case, you are better off cutting your losses and purchasing a new coffee mug. You can then use the preventative measures listed above to make sure this is a process you will no longer need to go through.


Mold in portable coffee mugs is fairly common, but fortunately easy to resolve. The molds found growing within them have the potential to cause health issues if consumed in great enough quantities, so be sure to use the methods listed above to keep your coffee mug as good as new after a mold infestation.

Chris Walker

Chris Walker has struggled for several years with mold after buying his own property. After finding the solutions to several issues around his home, he decided to create this site in order to answer as many questions about mold and mildew as possible to help others dealing with the same problems.

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