Sippy cups can make life easier by helping to prevent your baby from making messy spills, as she almost surely would if she used a normal cup. On the other hand, sippy cups are significantly harder to clean than normal cups. They have small openings in the "sippy" portion to allow only a little bit of fluid out of the cup at a time. It can be hard to reach into these small holes to clean out any mold. Keep your child safe by cleaning a moldy sippy cup thoroughly.
Fill a basin with hot water and add a squirt of dish soap. Mix thoroughly to distribute the soap throughout the hot water.
Remove the lid from the sippy cup. Remove as much mold as possible from the inside of the cup and discard the mold.
Place both the cup and the lid into the basin of hot, soapy water. Allow the lid and cup to soak for at least 5 minutes, or more if the mold is especially old or dried.
Scrub the inside and outside of the cup thoroughly with a sponge. Allow the lid to continue soaking as you do this. Focus especially on the grooves where the lid screws onto the cup, if applicable. Depending on the width and depth of the cup, you may need to use a bottle brush to clean the bottom and corners of the cup. Return the cup to the basin of hot, soapy water.
Scrub the visible and easily accessible parts of the lid with the sponge. Use a wet cotton swab to clean any areas you can fit it into. Stick toothpicks into the very small or narrow parts of the sippy cup's lid to force out any mold there. Rinse the lid thoroughly in the basin of hot, soapy water.
Rinse both the cup and lid thoroughly with cool water, then fill the cup with clean, hot water and put the lid back on. Turn the cup upside-down and pour out the hot water through the opening to flush out any remaining soap or contaminants. Remove the top from the cup and allow them to dry thoroughly.