Breastfeeding your baby with food sensitivities

Breastmilk is amazing! It changes in taste and composition based on what you eat. This means your baby gets to experience a variety of flavours, even before starting solids. 

Most babies enjoy and benefit from this variety and it’s not something you need to worry about. Occasionally, some babies may react to certain foods, but this isn’t anyone’s fault, it’s just how some babies respond.

Just as flavours from your diet pass through to your baby,¹ so do some food proteins² and other food chemicals.³ If your baby has a food sensitivity to any of these, they may have reactions.⁴  

There are different types of food sensitivity in babies, including food allergy and food intolerance. 

A food allergy happens when your baby’s immune system reacts to an allergen – in this case food. Even a tiny amount can cause a big reaction. Allergic reactions can happen quickly after a feed (like vomiting, reflux, or a rash) or take hours or days (such as blood in baby’s poo or eczema). The most common foods causing allergies are cows’ milk, soy, wheat, eggs, nuts, and fish.

Food intolerance is different. It doesn’t involve the immune system and reactions can be delayed, sometimes 24 to 48 hours or more after your baby is exposed. With intolerance, a small amount of food might not cause a reaction, but a larger amount could. 

Babies with food intolerance react to food chemicals coming through the breastmilk from their mother’s diet. These include food additives and natural chemicals found in healthy foods, often the things that give foods their flavour. Babies can also react to some everyday foods, such as dairy products, soy and some grains. 

It's possible for a baby to have both food allergy and food intolerance.

Allergies and intolerances can cause similar symptoms in breastfed babies, such as:

• wind
• gastro-oesophageal reflux
• green, mucousy poos
• eczema
• a wakeful baby who seems to be in pain

Babies can be unsettled for lots of reasons. Before changing your diet to try to prevent your baby’s symptoms, consider if your baby is unsettled due to

• low milk supply
• lactose overload from too much milk
• medical conditions like reflux disease, although this can be also associated with food allergy or intolerance, especially to cows' milk.⁵
• normal newborn behaviour, like fussy periods

Does your baby have other symptoms, like a rash or odd-looking poos? Ask your doctor to check for any medical causes, such as an ear or throat infection.

Lactose intolerance – where does it fit?

Lactose intolerance is different from food allergy or intolerance. Lactose is a natural part of breastmilk made in the breast, not from your diet. Sometimes, babies develop secondary lactose intolerance after an illness or allergy. For more, see Lactose intolerance and the breastfed baby.

If you’ve ruled out other causes and would like to check if your diet is affecting your baby, it’s important to consult a health professional before making any changes. When you’re breastfeeding, you need good nutrition. If you start cutting out foods, you’ll need to make up for what you’re missing by eating other foods.

• Breastfeeding is usually safe and beneficial, even if your baby has food sensitivities.
• There’s no need to avoid certain foods unless your baby is already showing symptoms.
• If your baby does have ongoing symptoms, your health professional may suggest changing your diet for a while to see if it helps.

Parents often hear different advice about preventing allergies. Should you avoid certain foods during pregnancy or while breastfeeding? Is exclusive breastfeeding important? When should allergenic foods be introduced? Here’s what research tells us:

• Avoiding foods during pregnancy or while breastfeeding does not reduce allergy risk.⁶
• Exclusive colostrum feeding in the first week can make a big difference in reducing peanut allergy.⁷
• Exclusive breastfeeding for around 6 months (at least the first 4 months) may help lower your baby’s risk.⁸
• Despite what you may hear, there is not enough evidence to recommend introducing allergenic foods before 6 months.⁹
• Your baby should start solids at around 6 months, mainly because babies need a new source of iron and zinc in their diet. 

• Begin major allergenic foods (like cows’ milk, soy, wheat, eggs, nuts, fish) soon after 6 months and before 12 months, unless your baby is already reacting.¹⁰
• It’s important to give these foods early on after 6 months and to give them frequently from then on.¹¹
• Delaying introducing allergenic foods doesn’t help and may increase risk.¹²  
• Keep breastfeeding as you introduce new foods. It may help reduce allergy risk.¹²

If your baby has reacted to foods in your diet, take extra care when starting solids. Eating foods directly can cause stronger reactions than when your baby was exposed through breastmilk. If you think your baby is having allergic reactions, talk to your doctor before introducing any of the riskier foods. A dietitian can also help you with starting solids.

If you think your baby is reacting to foods in your diet, it’s best to consult a health professional, such as a dietitian The Dieticians Australia website is a good place to search for a dietician experienced in food allergies and intolerances.

The information on this website does not replace advice from your health care provider.
 

© Australian Breastfeeding Association June 2026