Does My Baby Have Reflux or Cow’s Milk Protein Allergy?

Helping you understand the symptoms, differences and next steps

Many babies cry, spit up milk, or seem unsettled in the early weeks and months of life. As parents, this can be exhausting and worrying — especially when you’re not sure whether what you’re seeing is normal or a sign that something else is going on.

Reflux is very common in babies, but when symptoms are persistent, severe, or accompanied by other concerns, you may wonder whether cow’s milk protein allergy (CMPA) could be the underlying cause.

Although reflux and CMPA can look very similar, they are very different conditions and need different management approaches. Treating reflux symptoms alone won’t fully help a baby with CMPA — which is why understanding the difference is so important.

In this blog, I’ll explain:

• What reflux and CMPA are
• The symptoms of each (and where they overlap)
• Key clues to help you tell them apart
• Evidence-based treatment and management options
• When to seek professional support

 

What Is Baby Reflux?

Infant reflux — also known as gastro-oesophageal reflux (GOR) — happens when milk flows back from your baby’s stomach into the oesophagus. This can cause discomfort during or after feeds.

Some babies vomit or spit up milk, while others experience pain without any vomiting. This is referred to as silent reflux.

Reflux is extremely common:

• Around 50% of healthy babies regurgitate milk regularly in the first few months of life.
• It usually starts before 8 weeks of age
• Peaks at around 4 months
• Gradually improves between 6–12 months, as their digestive system matures

Common Reflux Symptoms in Babies

• Frequent spit-ups or vomiting
• Fussiness during or after feeds
• Back arching
• Coughing, hiccups or wet burps during feeds
• Excessive crying or irritability
• Unsettled, especially around feeding

Some babies may also experience slower weight gain if they struggle to keep their feeds down or aren’t taking their feeds well.

Uncomplicated reflux is usually limited to feeding and digestion concerns, without skin or respiratory symptoms.

 

What Is Cow’s Milk Protein Allergy (CMPA)?

Cow’s milk protein allergy is an immune reaction to proteins found in cow’s milk. It is one of the most common food allergies in babies and almost always develops before 1 year of age.

CMPA can affect both breastfed and formula-fed babies and is divided into two main types:

1. IgE-Mediated CMPA (Immediate Allergy)

Symptoms usually appear within 2 hours of consuming cow’s milk protein.

Common signs include:

• Hives, rash or redness
• Swelling of the lips or face
• Vomiting shortly after feeds
• Wheezing
• Persistent congestion or cough (not due to infection)

This type of allergy is often easier to recognise as symptoms appear soon after cow’s milk is consumed. Anaphylaxis is rare in babies, but any suspected immediate reaction should be assessed by a healthcare professional.

2. Non-IgE-Mediated CMPA (Delayed Allergy)

This is the most common form of CMPA in babies and can be more difficult to identify.

Symptoms typically appear 2–72 hours after consuming cow’s milk, making it harder to link symptoms directly to milk.

Possible symptoms include:

• Reflux that does not improve with standard reflux treatments
• Frequent vomiting or posseting
• Diarrhoea or loose stools
• Constipation
• Blood or mucus in stools
• Excessive wind and abdominal discomfort
• Prolonged crying or colic-like behaviour
• Eczema, especially if persistent or difficult to manage
• Feeding refusal or fussiness
• Slow or faltering weight gain

CMPA often affects more than one body system, such as the gut, skin and respiratory system — which is a key difference from uncomplicated reflux.

Babies With CMPA Often:

• Have a family history of allergies (eczema, asthma, hay fever and food allergy)
• Have reproducible symptoms every time cow’s milk protein is consumed
• Start developing symptoms:
  • When formula or cow’s milk containing foods are introduced to a breastfed baby
  • Within the first few weeks of life with a formula-fed baby

 

Why Reflux and CMPA Are Often Confused

Both reflux and CMPA can cause:

• Vomiting or spitting up
• Crying and fussiness during or after feeds
• Poor sleep and unsettled behaviour
• Symptoms that overlap with typical baby behaviour

In fact, up to 50% of babies with CMPA also have reflux-like symptoms, which can delay a diagnosis.

 

Reflux vs Cow’s Milk Protein Allergy: Key Differences

Feature	Reflux (GOR)	CMPA
Immune reaction	No	Yes
Affects skin or breathing	Rare	Common
Blood or mucus in stool	No	Yes (non-IgE)
Improves with feeding/position changes	Often	Not reliably
Requires milk elimination	No	Yes
Typical age pattern	Peaks early and improves by 12 months	Variable, improves over time with management

 

How Are Reflux and CMPA Diagnosed?

Reflux

Diagnosis is usually based on:

• Feeding history
• Symptoms
• Growth patterns

Investigations are rarely needed unless symptoms are severe or persistent beyond infancy.

CMPA

There is no single test for non-IgE CMPA. The gold standard for diagnosis includes:

1. Eliminate cow’s milk protein for 2–4 weeks
   • Breastfed babies: mum excludes all cow’s milk protein from their diets
   • Formula-fed babies: trial an extensively hydrolysed formula (eHF) or in some cases an amino acid formula (AAF)
2. Assess symptom improvement
3. Reintroduce cow’s milk protein to confirm diagnosis (food challenge)

Skin prick tests and blood tests are only helpful for suspected IgE-mediated CMPA.

 

Managing Baby Reflux

If reflux is causing discomfort, the following strategies can help:

• Offer smaller, more frequent feeds
• Avoid over-feeding
• Feed in a more upright position
• Keep baby upright after feeds when awake
• Burp regularly during and after feeds
• Review breastfeeding technique with a health visitor or lactation consultant

Additional options (under professional guidance) may include:

• Thickened formulas or if you are breastfeeding a thickener e.g. Instant Carobel or Infant Gaviscon.
• A trial of cow’s milk elimination if CMPA is suspected
• Acid-suppression medication in some cases

Most babies with uncomplicated reflux improve as they grow, with around 90% resolving before 1 year of age.

 

Managing Cow’s Milk Protein Allergy

For suspected or confirmed CMPA:

• Eliminate cow’s milk protein
  • Breastfed babies: for mum to start a milk-free diet
  • Formula-fed babies: use eHF or in some babies an AAF may be needed
• Confirm diagnosis with a controlled milk reintroduction
• Begin the milk ladder at around 9–12 months (non-IgE CMPA), with the help of your healthcare professional

 

When to Seek Professional Help

Speak to your Health Visitor, GP or a Paediatric Dietitian if your baby:

• Is not gaining weight as expected
• Has blood or mucus in their stools
• Has eczema or skin reactions
• Has respiratory symptoms or severe vomiting
• Shows symptoms across multiple systems
• You feel unsure about weaning or milk reintroduction

 

You Don’t Have to Navigate This Alone

Reflux and cow’s milk protein allergy can overlap in early infancy, but understanding the differences is key. While reflux is common and often improves with time, CMPA requires targeted dietary management and careful monitoring.

Delays in diagnosing CMPA are unfortunately still common, and parents often tell me they feel like they’re “getting nowhere”.

If you’re worried your baby’s symptoms might be related to cow’s milk protein allergy or reflux, you don’t have to figure it out alone.

As a Paediatric Dietitian specialising in non-IgE allergies, I support families to:
• identify possible food allergies
• manage elimination diets safely
• support feeding and growth
• guide milk reintroduction and the milk ladder

You can book a consultation or get in touch to discuss how I can help.