Making up infant formula

Bacteria in infant formula

Even when tins and packets of powdered infant formula are sealed, they can sometimes contain bacteria such as Cronobacter sakazakii (formerly known as Enterobacter sakazakii) and, more rarely, Salmonella. Although these bacteria are very rare, the infections they cause can be life-threatening.

To reduce the risk of infection, make up each feed as your baby needs it, using boiled water at a temperature of 70ºC or above. Water at this temperature will kill any harmful bacteria that may be present.

Make up feeds, one at a time, as your baby needs them.

Boiled water

Always use boiled water at a temperature of at least 70ºC, but remember to let the feed cool before you give it to the baby.

Bacteria multiply very fast at room temperature. Even when the feed is kept in a fridge, bacteria can still survive and multiply, although they do this more slowly. The risk of infection increases over time so that is why it is important to make up the feed only as your baby needs it.

Preparation and hygiene

A baby’s immune system is not as strong or as well developed as an adult’s. This means that babies are much more susceptible to illness and infection. Therefore, good hygiene is very important when making up a feed.

All equipment used to feed your baby must be sterilised. Bottles, teats and any other feeding equipment need to be cleaned and sterilised before each feed to reduce the chances of your baby falling sick or getting diarrhoea.

It is best to use boiled drinking water from the tap to make up a feed.
Do not use artificially softened water or water that has been previously boiled.

Bottled water

Bottled water is not recommended to make up a feed as it is not sterile and may contain too much salt (sodium) or sulphate. If you have to use bottled water to make up a feed, check the label to make sure the sodium (also written as Na) level is less than 200 milligrams (mg) per litre, and the sulphate (also written as SO or SO4) content is not higher than 250mg per litre. It is not usually sterile, so it will still need to be boiled, like tap water, before you prepare the feed.

 A step-by-step guide to preparing a powdered formula feed

• Step 1 Fill the kettle with at least 1 litre of fresh tap water (don’t use water that has been boiled before).
• Step 2 Boil the water. Then leave the water to cool for no more than 30 minutes so that it remains at a temperature of at least 70ºC.
• Step 3 Clean and disinfect the surface you are going to use.
• Step 4 It’s very important that you wash your hands.
• Step 5 If you are using a cold-water steriliser, shake off any excess solution from the bottle and the teat, or rinse the bottle with cooled boiled water from the kettle (not the tap).
• Step 6 Stand the bottle on a clean surface.
• Step 7 Keep the teat and cap on the upturned lid of the steriliser. Avoid putting them on the work surface.
• Step 8 Follow the manufacturer’s instructions and pour the correct amount of water that you need into the bottle. Double check that the water level is correct. Always put the water in the bottle first, while it is still hot, before adding the powdered infant formula.
• Step 9 Loosely fill the scoop with formula, according to the manufacturer’s instructions, and level it off using either the flat edge of a clean, dry knife or the leveller provided. Different tins of formula come with different scoops. Make sure you use only the scoop that is enclosed with the powdered infant formula that you are using.
• Step 10 Holding the edge of the teat, put it on the bottle. Then screw the retaining ring onto the bottle.
• Step 11 Cover the teat with the cap and shake the bottle until the powder is dissolved.
• Step 12 It is important to cool the formula so it is not too hot to drink. Do this by holding the bottom half of the bottle under cold running water. Make sure that the water does not touch the cap covering the teat.
• Step 13 Test the temperature of the infant formula on the inside of your wrist before giving it to your baby. It should be body-temperature, which means it should feel warm or cool, but not hot.
• Step 14 If there is any made-up infant formula left after a feed, throw it away.

Dos and don'ts

• As manufacturers’ instructions vary as to how much water and powder to use, it is important to follow the instructions very carefully.
• Do not add extra powdered infant formula when making up a feed. This can make your baby constipated and may cause dehydration. Too little powdered infant formula may not provide your baby with enough nourishment.
• Do not add sugar or cereals to the feed in the bottle.
• Never warm up infant formula in a microwave as it can heat the feed unevenly and may burn your baby’s mouth.

Useful links

Food Standards Agency
The Food Standards Agency is an independent government department responsible for food safety and hygiene across the UK.

© NHS