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How to Clean Sippy Cups

Medically Reviewed by Dr. Po-Chang Hsu, MD, MS
Updated
Learn how to keep sippy cups clean and free of mold.

Sippy cups are great for preventing spills, but all their little parts can make them difficult to clean thoroughly. They often end up misplaced, and by the time they’re found, they’re growing mold.

We have years of combined experience cleaning sippy cups, and we’ve done additional research to create this handy guide to help you protect your children by keeping your cups clean and free of mold.


Why Mold Grows In Sippy Cups

Sippy cups come in many different designs, but they all have a common purpose: to keep liquids inside the cup and prevent spills.

This is most commonly accomplished with a design that includes a cup, a spout, and some type of leak-proof valve.

While this ingenious engineering solves one problem, it creates another. Sippy cups have small parts and hard-to-reach corners that can easily trap particles of milk or juice and harbor harmful moisture, creating a perfect place for mold to grow.

Take Note

The most common place you will find mold on a sippy cup is in the spout, valve, or straw since they are the most difficult areas to clean thoroughly.

These small parts can sometimes be difficult to remove, leaving parents to believe that the valve is a permanent fixture on the lid. If this happens, the valve may never be removed, and over time, residue builds up and mold will grow.

What Should You Know About Mold?

Mold is a fungus that grows from tiny, microscopic spores. Mold spores are all around us and are relatively harmless in the small amounts we live with on a daily basis. However, mold becomes problematic when it grows.

The three things mold needs to grow are moisture, food, and warmth. In an environment with these three elements, the mold spores thrive and reproduce quickly.

When mold grows in homes, the biggest threat to a family’s health is breathing in the spores. The larger the patch of mold, the more spores can break off and be carried through the air, which the home occupants then inhale.

Take Note

Mold inhalation can cause the symptoms we commonly associate with mold: coughing, wheezing, asthma, nasal drainage, or other respiratory illnesses (1).

The dangers from mold growth in sippy cups, however, are different. If mold grows in a cup, the primary threat is an illness from ingesting the mold rather than inhaling it.

What If My Child Ingests Mold?

Don’t panic if you find that your child has used a sippy cup with mold or mildew. Not all molds are toxic, and not all children will react to mold (2).

However, you should try to be vigilant about cleaning your child’s cups properly to reduce their chances of mold exposure, as some are indeed toxic and can have harmful effects on health.

Some symptoms children may experience after ingesting mold are:

  • Abdominal cramps.
  • Vomiting.
  • Diarrhea.
  • Dehydration.
  • Nausea.

If a child has an allergy to mold, they could experience more acute symptoms commonly associated with food allergies, such as:

  • Rashes.
  • Breathing difficulties.
  • Swelling of the face, lips, or tongue.
  • Tingling sensation.
  • Sneezing.
  • Running nose.
  • Nasal congestion.
  • Coughing.
  • Wheezing.
  • Flu-like symptoms.

Can I Eliminate Mold Completely?

Substances that kill mold include bleach, vinegar, and tea tree oil (3). However, if you use these substances, make sure to dilute them well and wash your child’s sippy cups to remove any chemical residue after disinfecting them.

High heat also kills mold, which means steam sterilizers or boiling water can be used to kill mold spores.

Keep In Mind

It’s not possible to eliminate mold entirely from your life as the spores are always present in the air. However, it is possible to clean your baby’s sippy cup thoroughly to remove the fungus and make it safe for your little one to use again.

It’s also possible to reduce the chances of mold growth in the first place.

How to Clean a Sippy Cup

By taking these steps when cleaning your sippy cups, you can prevent mold growth.

1. Rinse Immediately After Use

Even if you don’t plan to wash your child’s cup right away, it’s a good idea to rinse it immediately. This removes some of the milk/juice particles, leaving less food residue in the cup for mold spores to eat and grow.

2. Completely Disassemble Sippy Cup

When you’re ready to wash your child’s sippy cup, make sure you disassemble every part. Food, milk, and juice particles get wedged in the tightest of spaces, and this is where parents most commonly find mold. To clean a sippy cup thoroughly, all parts must be accessible.

If your sippy cup has a pop-up straw, remove it. Typically inside the lid, there is a rubber stopper or other mechanism; remove this from the cup as well as any rubber rings around the edge.

3. Soak In Hot Water And Soap

Make sure that the water is deep enough to submerge your sippy cups and accessories fully. Soak them for 15 minutes in hot, soapy water. This will soften dried-on or stubborn gunk, allowing you to clean it off easily. Alternatively, you can dissolve denture tablets in water before soaking sippy cup parts. This helps get rid of stubborn gunk in the cup as well.

4. Clean Your Cups

Avoid using a sponge as they have been shown to harbor bacteria (4). Use a clean dishrag or bottle brush instead for the insides of the sippy cups.

If your sippy cup has a spout, a nipple brush can help you get into the small spaces. If it has a straw, you can purchase a straw brush to clean it. Inspect the stopper and valve for visible mold, and clean it with a nipple or straw brush.

To access the inside of the valve or closed spout, pinch the plastic together, and you should gain access.

Finally, wash the lid of the sippy cup. Carefully inspect and wash all the crevices to ensure there are no remaining food particles or mold.

Pro Tip

You can use a toothpick, Q-tip, pipe cleaner, or toothbrush to get into the tiny, difficult-to-clean spaces in the lids or valves.

5. Sanitize Your Cups (Optional)

While not completely necessary, occasionally sanitizing your sippy cups can contribute to your peace of mind. You can do this by using the same steps you use for sanitizing baby bottles. Here are three quick options:

  • Sanitize With Bleach: Mix 2 teaspoons of bleach with a gallon of water. Allow cups to soak for two minutes, then drip dry (5).
  • Sanitize With a Steam Sterilizer: Steam sterilizers are made for the microwave or are available as a counter-top accessory. They emit high-temperature steam that will kill bacteria and mold spores.
  • Boil Your Cups: Place your sippy cups and accessories into a pot of boiling water. Allow to boil for 10 minutes.

6. Dry Cups Thoroughly

Never reassemble or put away cups while they still have moisture. Moisture is one of the core components of mold growth, and if you re-assemble your cups before they’re dry, that moisture can become trapped in small spaces and encourage mold growth. So, allow your sippy cups to sit on a drying rack for good airflow.

Never dry sippy cups on a towel as fabrics can harbor bacteria.

7. Throw Away Stained Cups

If you have a particularly moldy cup that continues to remain stained after a thorough washing, it’s better to be safe than sorry — toss it in the trash. While there may not be live mold spores still present, it’s impossible to tell for sure. Consider switching to new sippy cups every three months to prevent mold growth.


Clean Sippy Cups Are Possible!

Because of all the nooks and crannies located inside sippy cups, they can, unfortunately, trap small food particles and grow mold quickly.

By completely taking them apart, washing all pieces thoroughly, and allowing them to dry before reassembling, you reduce the risk of providing the three elements mold needs to grow: food, water, and warmth.

Headshot of Dr. Po-Chang Hsu, MD, MS

Medically Reviewed by

Dr. Po-Chang Hsu, MD, MS

Po-Chang Hsu, MD received his medical degree from Tufts University in Boston, Massachusetts. Dr. Hsu has interests in both pediatrics and neonatology, and he also loves writing, walking, and learning new languages.