Safe Formula Milk Temperature for Infants: What Parents Should Know

The temperature of formula milk foam?

Hello Doctor, my baby is 4 months old and currently on formula milk.
On August 7th, while we were out, I prepared freshly boiled water and stored it in a thermos.
About four hours later, I took it out to mix the formula, and it felt like the temperature was lower than the usual 70 degrees Celsius.
However, I let my baby drink it at that time.
Later, I borrowed water twice at a friend's house to feed the baby, but I found out that the temperature was only 55 degrees Celsius.
Since there were three meals with this situation, I am a bit worried about potential bacterial infections.
Currently, my baby has no symptoms of diarrhea or vomiting.
Should I be concerned about infections such as Salmonella, Listeria, or Enterobacter sakazakii? Given that Listeria has a longer incubation period, are there specific symptoms I should monitor for in my baby? Thank you, Doctor!

Xinshou Ma, 20~29 year old female. Ask Date: 2021/08/08

Dr. Xiao Kaiwen reply Pediatrics

If I want to prepare formula milk with water that has already been boiled, in principle, there should not be any pathogenic bacteria present.
Even if the water has been left to cool for a while, the likelihood of pathogenic bacteria developing should be low, especially since it is consumed only occasionally.
Therefore, I believe the risk of developing a disease is minimal and there is no need to worry excessively.
Symptoms of ingesting pathogenic bacteria typically include gastrointestinal symptoms such as vomiting, diarrhea, and fever.

Reply Date: 2021/08/08

More Info

When it comes to preparing formula milk for infants, ensuring the right temperature is crucial for both safety and nutritional integrity. For a 4-month-old baby, the recommended temperature for formula milk is typically around body temperature, which is approximately 98.6°F (37°C). This temperature is comfortable for the baby and helps to preserve the nutrients in the formula.

In your case, you mentioned that the water used for preparing the formula was initially boiled and then stored in a thermos for about four hours. While boiling water does kill most harmful bacteria, the concern arises when the water cools down to lower temperatures, such as the 55°C (131°F) you noted. At this temperature, while it is still hot enough to mix with the formula, it may not be sufficient to eliminate any potential bacteria that could have been introduced after boiling, especially if the formula itself was not properly handled.

The risk of bacterial contamination, such as Salmonella, Listeria, or Enterobacter sakazakii, is a valid concern when preparing formula milk. These bacteria can cause serious infections in infants, whose immune systems are still developing. However, if your baby has not shown any symptoms such as diarrhea, vomiting, or fever, the risk of infection is likely low. It's important to remember that the symptoms of bacterial infections can vary, and some may not appear immediately, especially in the case of Listeria, which has a longer incubation period.

To minimize the risk of infection in the future, here are some guidelines to follow:
1. Use Proper Water Temperature: Always ensure that the water used to prepare formula is at least 70°C (158°F) when mixing with the formula. This temperature helps to kill any bacteria present in the formula powder.

2. Immediate Use: Once the formula is prepared, it should be used immediately. If not used right away, it should be stored in the refrigerator and consumed within 24 hours.

3. Avoid Reheating: If you prepare formula and it is not consumed, do not reheat it multiple times. Bacteria can grow in formula that has been warmed and cooled repeatedly.

4. Observe for Symptoms: Keep an eye on your baby for any signs of gastrointestinal distress, such as watery stools, vomiting, or fever. If any of these symptoms occur, consult your pediatrician promptly.

5. Hygiene Practices: Always wash your hands before preparing formula, and ensure that all bottles and nipples are properly sterilized to prevent contamination.

In summary, while the occasional exposure to slightly lower temperatures may not pose a significant risk, maintaining the correct preparation and storage practices is essential for your baby's health. If you have ongoing concerns about your baby's health or feeding practices, do not hesitate to reach out to your pediatrician for personalized advice and guidance.

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