Picking a formula milk to feed your baby can feel like a big decision – there are so many to choose from. But the good news is that changing formula milk is perfectly safe1, so if you decide to make a switch, it’s absolutely fine to do so.
There are several reasons you might be considering changing formula milk. You might feel that a particular brand doesn’t agree with your baby, or maybe your healthcare professional has recommended switching to a specialist formula milk such as anti-reflux formula.
Whatever your reason for changing formula milk, use our guide to help you make the transition smoothly.
Yes, you can change the type or brand of formula that you’re feeding your baby. There’s no evidence that doing so will do your baby any harm1.
Having said that, it’s always best to speak to your GP or health visitor before changing baby formula. They’ll be able to help you make an informed decision about whether to switch formula, what to switch to, and how to make the transition.
There are several reasons why you might be considering changing formula milk.
Some of the most common reasons include:
If you’re thinking about changing formula milk, there are different methods of introducing a new brand formula to your baby. Sometimes, your doctor might recommend a straight swap from your current formula to a new formula milk, depending on why you’re making the change3.
However, if you’re planning to switch to a different brand of formula milk, it’s recommended to do so gradually, to give your baby’s digestive system time to adapt to the new compositional profile.
To introduce a new formula milk slowly, start with one feed of the new formula milk a day – ideally earlier in the day rather than later – while keeping all of the other feeds to your baby’s usual formula milk. Once this feed has become established (which can take two to three days), you can introduce a second feed of the new formula milk. Continue in this way until all of the feeds are with the new formula milk.
It can take quite a while to switch, but taking things slowly ensures that your baby has time to adjust, and that you feel confident and reassured they’re taking to it well.
Below are some types of baby formula you might consider switching to, and why.
Your healthcare provider can advise you on whether you need to change formula milk, and whether to change straight away or more gradually.
If your baby is showing symptoms of reflux, your healthcare professional might have advised you to consider switching to an anti-reflux formula milk.
Suitable from birth, anti-reflux formula is a specially thickened formula designed to help feeds stay down1.
It’s likely that you’ll need to prepare the anti-reflux formula slightly differently from your usual baby formula milk, because of the difference in thickness and ingredients. Always follow the instructions on the side of the tub1 when making up your baby’s bottle.
We also recommend using a single-hole, fast-flow teat to make it easier for your baby to get the milk they need when bottle-feeding with anti-reflux formula.
Before you switch to an anti-reflux formula, it’s important to speak to your healthcare professional and get a medical diagnosis before changing baby formula, just to make sure it’s right for your baby.
Hungry baby formula is a formula suitable from birth, containing more casein than whey protein, which takes slightly longer to digest1.
During the first few weeks, all babies, whether they are being breast or bottle-fed, tend to need feeding very frequently – hourly feeds are not uncommon. This is because newborns have very tiny tummies, which are easily filled up in one go. This frequent demand for feeding can be mistaken as the baby being unusually hungry, so it’s important to ask your midwife, health visitor, or GP for advice before making the switch.
Comfort milk is specially designed and contains partly broken down proteins which may make it easier for babies to digest1. Your midwife or GP may recommend switching to comfort milk if your baby is experiencing digestive problems such as colic or constipation.
Once your baby’s digestive system has had a chance to mature, you may like to move back onto a standard infant formula. If you do decide to change to a standard formula, try and do so gradually and keep an eye out in case your baby’s colic or constipation symptoms reappear.
As well as how to switch your baby’s newborn’s formula milk, you may also be thinking about moving on to a follow-on milk or toddler milk as your baby grows.
Follow-on milk is suitable for babies from 6 - 12 months as part of their weaning diet. Toddler milk is suitable for your baby from their first birthday1. Always check with your midwife, health visitor or GP before changing baby formula, including moving on to a follow-on or toddler milk.
If you like, you can also switch from formula milk to whole cow’s milk as your baby’s main drink after their first birthday4. Make sure your baby has between 300 and 500ml of milk per day to ensure they’re getting enough calcium for their development without reducing their appetite for food5.
There’s no evidence that changing formula milk will do your baby any harm1, and you may find that your baby immediately adjusts to their new formula with no issues.
However, it’s also completely normal for your baby to go through a small period of adjustment to their new formula, and you might notice some changes in their nappy as their body gets used to the new composition. This period will likely be short, but if you have any concerns, you should talk to your healthcare professional for advice and reassurance.
Any time you move onto a new formula milk, you’re advised to check the preparation instructions to ensure you’re up to date with the latest advice on how to prepare a feed.
Preparation instructions have changed over the years to keep in line with emerging health and safety regulations. But you’ll always find an up-to-date, step-by-step guide on our website, and on the back of each pack.
You can find our in-depth guide on preparing a formula feed here.
A small change in your baby’s nappy habits can be normal when changing formula milk. In fact, some formulas can cause your baby’s poos to appear dark green6. However, if your baby’s poo becomes watery or foul-smelling, you should speak to your healthcare provider7.
Some babies might adjust to a new formula straight away, while others may need an adjustment period of a few weeks. This is why it can be helpful to introduce a new formula gradually, to help your baby’s body adapt to the composition.
Changing baby formula can cause some temporary changes in your baby’s stomach, which might lead to smellier poos and gas for a little while. If you have any concerns, you should speak to your GP, midwife or health visitor.
Last reviewed: February 2026
Reviewed by Nutricia’s Medical and Scientific Affairs Team
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Important notice
Breastfeeding is best for babies and provides many benefits. It is important that, in preparation for and during breastfeeding, you eat a varied, balanced diet. Combined breast and bottle feeding in the first weeks of life may reduce the supply of your own breastmilk, and reversing the decision not to breastfeed is difficult. The social and financial implications of using an infant formula should be considered. Improper use of an infant formula or inappropriate foods or feeding methods may present a health hazard. If you use an infant formula, you should follow manufacturer’s instructions for use carefully – failure to follow the instructions may make your baby ill. Always consult your doctor, midwife or health visitor for advice about feeding your baby.
