I have gone on vacation for a month and forgot to clean my mug thay i left on the counter.

Im scared that after washing it out with soap and HOT water it isn't safe to drink out of. i boiled water in the kettle and let the boiled water sit in the mug for 10 minutes

This is a very special mug and i would hate to throw it away.

Is it safe??

  • 1
    Welcome! Could you please explain what material the mug is made of? This will determine what kind of cleaning it can stand up to and what the probability of mold residue is. You can always edit your post to add more details. As for all new users, I would recommend you take the tour and browse through the help center to get a good overview of how the site works.
    – Stephie
    Mar 24, 2021 at 14:56
  • There’s also a good chance that your question is a duplicate of others we already have, for example this one, or this one, but we need your input here.
    – Stephie
    Mar 24, 2021 at 14:58
  • There is also a good chance that what you're seeing is not mold at all. How much coffee was left in it, and was it straight coffee or a latte/cappuccino kind of thing? Milk does strange things and acquires a weird appearance when it dries and the fats become unhomogenized as it dries. A picture or two would help us help you understand if the other questions answer yours already or if there's something else going on. Also, what material is the interior of the mug? It makes a difference between glass, glazed porcelain or stoneware, unglazed stoneware, stainlessness steel, etc.
    – R Mac
    Mar 25, 2021 at 13:01
  • 2
    This is either a duplicate (see other comments) or needs more details. VTC. Happy to retract my vote or reopen if OP supplies mire details as requested.
    – Stephie
    Mar 28, 2021 at 7:16

1 Answer 1


It is safe.

If you clean it by either putting it in a dishwasher on a high temperature setting or sterilizing it with boiling water, you will be fine.

This is not specifically a question about coffee but about food safety in general, so usual measures apply:

  1. Scrape off as much of the mold as possible
  2. Put the dish into (boiling) hot water for at least 15min

It is a similar procedure to preparing glass jars for jam, you try to boil away as much bacteria and funghi as possible.

  • yes, do not pour (soon no longer) boiling water into the mug, submerse the mug in a pot of boiling water.
    – ths
    Apr 27, 2021 at 23:47

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