When you shop through links on our site, we may earn an affiliate commission. This educational content is not intended to be a substitute for professional medical advice.

How to Clean Sippy Cups

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

Does your little one use sippy cups? If so, then you’ve probably found a few lost under the couch and, by the time they were retrieved, had mold or mildew growing in them.

Sippy cups are great for preventing spills, but all their little parts can make them difficult to clean thoroughly.

In this guide, we will show you how to keep your sippy cups clean and mold-free.

Why Mold Grows In Sippy Cups

Sippy cups are manufactured with many different designs, but a common purpose: to keep liquids inside the cup and prevent spills.

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

While this ingenious engineering solves one problem, it creates another. The 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 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, too, leaving parents to believe that the valve is a permanent fixture on the lid. If this happens, the parent never removes the valve 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 relatively harmless in the small amounts we live with on a daily basis.

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 causes the symptoms we typically associate with mold exposure: coughing, wheezing, asthma, nasal drainage, or other respiratory illnesses.

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 breathing it in.

What If My Child Ingests Mold?

If you find that your child has used a sippy cup with mold or mildew, don’t panic. Not all molds are toxic, and not all children will react to mold (1).

However, going forward, 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 (2). If you use these substances, however, 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 once again.

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

How to Clean a Sippy Cup

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 to prevent leaks.

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 in it. This helps get rid of stubborn gunks in the cup as well.

4. Clean Your Cups

Avoid using a sponge as they have been shown to harbor bacteria (3). 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; 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 of 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 using the same steps 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 (4).
  • 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 which will kill bacteria and mold spores.
  • Boil Your Cups: Place your sippy cups and accessories into a pot of boiling water. Allow boiling for 10 minutes.

6. Dry Cups Thoroughly

Never re-assemble 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 in 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 have a stain 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 re-assembling before, you reduce the risk of providing the three elements mold need to effectively 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.