Updated September 2026 to reflect current guidance and formula options for babies with cow’s milk protein allergy.
If your baby has been diagnosed with cow’s milk protein allergy (CMPA), you may have been told they need a specialist formula. But when you start looking at the different options, it can get confusing very quickly.
You might be wondering which formula is best for CMPA, why your baby has been given one formula rather than another, or what the difference is between extensively hydrolysed and amino acid formula.
For most babies with CMPA, an extensively hydrolysed formula is usually the first option. Some babies will need an amino acid formula instead, depending on their symptoms and how they respond.
As a specialist paediatric allergy dietitian, some of the most common questions I hear from parents are:
- What’s the best formula for CMPA?
- What’s the difference between the different milk allergy formulas?
- How do I know if the formula my baby has been given is right for them?
In this guide, I’ll take you through the different types of formula used for CMPA, some of the brands you may come across and when each type might be considered.
Extensively Hydrolysed Formula (eHF): Usually the First Formula Tried for CMPA
If your baby has CMPA, an extensively hydrolysed formula — usually shortened to eHF — is often the first specialist formula they will be prescribed.
These formulas are still made from cow’s milk protein, but the protein has been broken down into much smaller pieces called peptides. This makes it much less likely to trigger an allergic reaction.
For many babies with CMPA, an eHF is enough to help symptoms settle, which is why it is commonly used before moving on to a more specialist amino acid formula. Guidelines commonly use the standard that a hypoallergenic formula should be tolerated by at least 90% of infants with confirmed cow’s milk allergy.
Common brands of extensively hydrolysed formula for babies with milk allergy include:
- Aptamil Pepti
- Aptamil Pepti Syneo
- Nutramigen LGG
- SMA Althéra
The formulas are all slightly different, and babies can vary in how well they accept the taste. If your baby is struggling with one brand, speak to your GP, paediatrician or dietitian rather than swapping repeatedly on your own.
Amino Acid Formula (AAF): When a More Specialist CMPA Formula Is Needed
If your baby’s symptoms do not improve on an extensively hydrolysed formula, or if their allergy is more severe, they may be prescribed an amino acid formula, usually shortened to AAF.
Amino acid formulas are made from the individual building blocks of protein rather than larger protein fragments. This means they do not contain intact cow’s milk protein chains, so they are much less likely to trigger an allergic reaction.
An amino acid formula may be considered if:
- your baby does not improve on an extensively hydrolysed formula
- your baby has more severe symptoms
- there are concerns about growth or feeding
- your baby has multiple food allergies
- your healthcare team feels an amino acid formula is more appropriate from the outset
Some of the amino acid formulas you may come across include:
How Long Should I Try a CMPA formula?
When your baby starts a new specialist formula, it can be tempting to decide very quickly whether it is working — especially if they are still uncomfortable or refusing the bottle.
For many babies, it can take a little time for symptoms to settle and for them to get used to the different taste and smell of a hypoallergenic formula. In some situations, your healthcare professional may advise a trial of around 1–2 weeks before deciding whether the formula is suitable.
Try not to swap between formulas too quickly unless your GP, paediatrician or dietitian advises you to, as this can make it harder to work out what is actually helping.
What If My Baby Won’t Drink Hypoallergenic Formula?
If your baby is refusing their new formula, you’re definitely not alone. Hypoallergenic formulas can smell and taste quite different from standard infant formula, and some babies need a little time to get used to them.
It can be really stressful when you know they need the formula but they just don’t seem to want it. Sometimes it is simply about giving them a little time to adjust, but if your baby is refusing feeds, taking much less than usual or you’re worried they’re not getting enough, it’s worth getting some individual advice.
There are a few things that can help depending on your baby’s age, symptoms and feeding history, but I wouldn’t suggest changing formula repeatedly without support because that can make it harder to work out what’s actually going on.
If you’re struggling with this, I can help you look at the full picture and work out what the next step should be.
Soy Formula for Babies with CMPA
Parents often ask me whether soy formula can be used instead of a specialist cow’s milk allergy formula.
Soy formula is free from cow’s milk protein, but it isn’t usually the first choice for babies with CMPA, particularly in younger babies.
For babies under 6 months, soy formula is generally not recommended. After 6 months, it may sometimes be considered depending on your baby’s age, symptoms, feeding history and whether they also react to soy.
Some babies with CMPA can also react to soy, especially those with delayed, non-IgE symptoms, so it is not something I would suggest switching to without discussing it with your healthcare professional first.
Soy formula may be considered in some circumstances, including for families who need a non-cow’s-milk option for religious or ethical reasons, but whether it is suitable really depends on the individual baby.
If you are wondering whether soy formula is an option for your baby, it is worth looking at the full allergy and feeding history rather than just swapping formulas.
Why the caution with soya formula
Guidance from the British Dietetic Association’s Paediatric Specialist Group (2022) advises that soy formula should not be used under 6 months of age, except in exceptional circumstances. This is due to the potential health risks linked to phytoestrogens (plant oestrogens found naturally in soy). After 6 months, soy formula may be considered a suitable option for some babies with cow’s milk protein allergy, particularly in families following a vegan diet.
Some soy-based infant formulas available internationally include:
Similac Soy Isomil – USA
Enfamil ProSobee Soy – USA
Gerber Good Start Soy – USA
Karicare Soy – Australia & New Zealand
Alula Gold Soy – Australia
There are currently no soy-based infant formulas available in the UK, so these are mainly relevant for families reading from the US, Australia and New Zealand.
Rice-Based Formula for Babies with CMPA
Hydrolysed rice formula is another option that may sometimes be used for babies with cow’s milk protein allergy.
Instead of cow’s milk protein, these formulas use hydrolysed rice protein. They are designed to be nutritionally complete for babies, but they are still much less commonly used in the UK than extensively hydrolysed or amino acid formulas.
One UK option you may come across is Arizé.
When might rice formula be considered?
Rice-based formula may be considered if:
- your baby has CMPA and another type of specialist formula has not been suitable
- your baby struggles with the taste of an extensively hydrolysed or amino acid formula
- your family needs a formula that does not contain animal-derived protein
- One thing parents often like about rice-based formula is that the taste can sometimes be more acceptable than some hydrolysed cow’s milk formulas.
Is rice formula safe for babies?
Hydrolysed rice formulas are designed to provide the nutrients babies need for growth and development. Research has shown good tolerance and normal growth in babies with cow’s milk allergy who use them.
It is important, though, that rice-based infant formula is not confused with rice milk from the supermarket.
Rice milk is not a suitable main drink for young children and should not be used instead of infant formula.
If you are considering a rice-based formula for your baby, I would always recommend discussing it with your GP, paediatrician or allergy dietitian first, as whether it is suitable depends on your baby’s symptoms, age and feeding history.
In my own practice, rice-based formula is still something I come across much less often than extensively hydrolysed or amino acid formula.
Other rice-based formula options available internationally include:
- Novalac Rice AR – Europe
- Blemil Plus Hydrolysed Rice – Spain
- Modilac Expert Riz – France
These products are not all available in the UK, but I’ve included them because families reading this guide may be based in different countries.
Does CMPA Formula Give My Baby Everything They Need?
This is something parents ask me a lot, especially when their baby has just been switched onto a specialist formula.
The reassuring answer is yes. Extensively hydrolysed and amino acid formulas are designed to be nutritionally complete, which means they provide the energy, protein, fats, vitamins and minerals your baby needs for growth and development.
They are made differently from standard infant formula because the protein has been broken down or replaced with amino acids, but they are still carefully formulated to meet babies’ nutritional needs.
A few things parents often worry about are:
- Protein – specialist formulas still provide enough protein for growth, just in a form that is suitable for babies with CMPA.
- Calcium and vitamin D – these formulas are fortified with key nutrients needed for bones and development.
- Growth – babies can grow normally on specialist CMPA formula when it is suitable for them and being taken in adequate amounts.
If your baby is growing well and taking their prescribed formula, you can feel reassured that it is designed to meet their nutritional needs.
If your baby is struggling with feeds, taking very small amounts or not gaining weight as expected, that is when it is worth getting individual support rather than simply changing formula.
Worried your baby isn’t taking enough formaula?
Follow-On Formula for Babies with CMPA
Once your baby reaches 6 months, you might wonder whether you need to move onto a follow-on version of their specialist formula.
In most cases, if your baby is doing well on their current stage 1 CMPA formula, there is no need to change simply because they have reached 6 months.
Some specialist formulas have follow-on versions, but whether a change is needed depends on your baby’s individual needs, growth, symptoms and feeding history.
If you are unsure whether your baby should stay on their current formula or move onto something different, it is worth discussing this with your GP, paediatrician or allergy dietitian.
Examples of specialist follow-on formulas include Aptamil Pepti 2 and Nutramigen LGG 2.
Breastfeeding and CMPA
Breast milk remains the preferred source of nutrition for babies, including those with cow’s milk protein allergy, and a diagnosis of CMPA does not usually mean you need to stop breastfeeding.
If your baby is reacting to cow’s milk protein while breastfeeding, you may be advised to remove cow’s milk from your own diet for a short period while symptoms are assessed.
If you do need to follow a milk-free diet, it is important that your own nutritional needs are looked after too, particularly calcium, vitamin D and iodine.
You can read more about breastfeeding and cow’s milk allergy in my separate guide.
Which CMPA Formula Is Best for My Baby?
There isn’t one formula that is right for every baby with cow’s milk protein allergy.
For many babies, an extensively hydrolysed formula is the first option. Some babies may need an amino acid formula, while soy or rice-based formulas may be considered in certain situations.
What is most suitable will depend on your baby’s age, symptoms, growth, feeding history and how they have responded to previous formulas.
The important thing is not to keep changing formulas without support, especially if your baby is still having symptoms, struggling with feeds or not gaining weight as expected.
Need Help Understanding Your Baby’s CMPA Formula?
If your baby has already been prescribed a specialist formula and you’re still feeling unsure about their symptoms, feeding or whether things are improving, I can help you work through it.
In a consultation, I can review your baby’s symptoms, feeding history, growth and current formula, and help you understand what questions to ask and what the next steps may be.
Hannah Whittaker RD is a specialist paediatric allergy dietitian with over 20 years’ experience in nutrition and 10 years as a Registered Dietitian. She specialises in food allergy in babies and children, including cow’s milk, egg, soya, wheat, peanut and tree nut allergy, food reintroduction and nutritional adequacy.
Hannah has worked in NHS paediatrics and now supports families with practical, evidence-based nutrition advice. She is also an experienced media spokesperson and has contributed to publications including The Sunday Times, The Independent and Huffington Post.
Credentials
Registered Dietitian
First Class Degree in Nutrition
Postgraduate qualification in Dietetics
Experience
Over 20 years’ experience in nutrition
10 years as a Registered Dietitian
NHS paediatric dietetics experience
Media spokesperson in the UK and internationally
Writer, committee member and researcher supporting the British Dietetic Association
