Allergies and intolerance

Food allergies and food intolerances are not the same and it is essential to understand how to distinguish between the two conditions

Allergies and intolerances are not the same. A food allergy is an adverse reaction to the protein component of a food, which evokes an immunological response. When this is severe, it may result in anaphylaxis. An intolerance is an adverse reaction to a ‘non-protein’ component in the food, which does not involve the immune system and reactions may be delayed, the symptoms are often gastrointestinal or skin-related.

Lactose intolerance

Lactose intolerance is caused by a reduced level of the enzyme lactase, which breaks down the lactose in milk so that it can be absorbed into the blood. It is often a temporary problem, lasting between a few days and a few weeks. It can also occur after gastroenteritis (an infection causing vomiting or diarrhoea). It is also thought to be a possible cause of colic.


  • Bloated stomach, possibly with abdominal pain
  • Wind
  • Loose stools or diarrhoea
  • Mild colic
  • Poor weight gain or even weight loss.


If a baby might be suffering from lactose intolerance, refer the customer to a pharmacist, who will most likely refer to a GP or health visitor for specialist advice.

Formula milks

Once lactose intolerance has been diagnosed, a lactose-free formula (e.g. Aptamil Lactose Free or SMA LF) may be recommended. These are nutritionally complete milks that can be used from birth for infants who have a congenital or temporary lactase deficiency. These milks taste similar to routine infant formula milk, so babies should not notice a difference. 

Protein or lactose?

Babies can react to the cows’ milk protein that passes through breast milk or that is used to make infant formula milk, or they may have difficulty digesting lactose (a natural sugar found in milk). It is important to ascertain whether it is the protein or the lactose that is causing the problem.

Cows' milk allergy

Cows’ milk allergy (CMA), also known as cows’ milk protein allergy (CMPA), is the most common food allergy in infants and is more frequently seen in formula-fed than breastfed babies. It is thought to affect two to 7.5 per cent of babies under one year of age, although the majority will grow out of it by the age of five.


There are a number of different symptoms, which generally involve the skin and one or more other body system, including the gastrointestinal and respiratory systems. Symptoms may include:

  • Swelling of the face, hives, wheezing
  • Diarrhoea and vomiting
  • Constipation, bloating and abdominal pain
  • Colic.

Other symptoms can include eczema, rashes and breathing difficulties in severe cases (refer these cases to the pharmacist). Between 50 and 60 per cent of babies with atopic eczema will also have an allergy to cows’ milk, causing their skin symptoms to worsen.


The first time a baby has cows’ milk (whether in an infant formula milk or if it passes through breast milk), their immune system reacts to the protein it contains as if it were a foreign substance. The next time the baby has cows’ milk, the antibodies produced will trigger the various allergy symptoms.


If you think a baby may be allergic to cows’ milk, refer to the pharmacist as they may need to see a GP for a diagnosis. Total avoidance of cows’ milk protein is usually required, which may involve mothers of breastfed infants avoiding cows’ milk and dairy products, alongside taking appropriate supplements (e.g. calcium and vitamin D). The situation should be monitored using a food and symptom diary, with cows’ milk being periodically reintroduced at intervals under medical supervision. For formulafed infants, a suitable formula will need to be found that is tolerated as a drink, and for use in cereals and cooking.

Formula milks

The latest guidance advises using an extensively hydrolysed formula (EHF) such as Aptamil Pepti 1 or 2, which is still based on cows’ milk, although the proteins have been broken down to make them less allergenic. There are also amino acid-based formulas (AAFs) where the protein is made up of individual amino acids so that it does not trigger allergic reactions.

AAFs are considerably more expensive, so are usually reserved for those with severe cows’ milk or multiple food allergies who cannot tolerate EHFs. The Department of Health recommends that soya-based formula milks (e.g. SMA Wysoy) are not used before six months of age. This is because infants may also be allergic to soya protein and these formulas increase exposure to plant phytoestrogens while babies’ organ systems are immature and vulnerable.

However, some milks are marketed from birth, as for some babies this may be all that they can tolerate. They can be used for babies who cannot tolerate the EHFs as they are more palatable, or for those who choose soya-based formula for lifestyle reasons, such as vegetarians and vegans.

N.B. Vegan diets are not recommended for babies.

Help for parents

Parents may require additional support and information, ideally from a dietitian, especially as their baby gets older and starts weaning onto solid foods. Knowing plenty of milk-free recipes will be helpful. There are also a number of dairy-free products available to buy now. The labels of all foods should be checked for their contents as milk can be present where it is not expected.

Clinical summary:

Food allergy is an adverse immune response and may be immunoglobulin-E (IgE; an antibody)- mediated or non-IgE-mediated (in which case T-cells are thought to be responsible), or both. IgEmediated reactions are acute and often have a rapid onset, e.g. skin reactions, angioedema of the lips, tongue and palate, nausea and vomiting, respiratory symptoms (sneezing, rhinorrhoea, cough, wheezing or shortness of breath). Non-IgEmediated reactions tend to be delayed, e.g. itching, atopic eczema, gastro-oesophageal reflux disease (GORD), changes in stools, tiredness and faltering growth.

According to NICE, diagnosis should be considered in a child whose symptoms do not adequately respond to treatment for atopic eczema, GORD or chronic GI problems including constipation, aided by taking an allergy-focused clinical history (e.g. personal and family history of atopy, symptom type, severity, duration and reproducibility, and dietary details). The child should also be assessed for physical signs of malnutrition or faltering growth, and signs of any allergy-related comorbidities.

Management of the suspected food allergy depends on whether or not IgE is thought to be responsible. If an IgE-mediated reaction is believed to be causing the infant’s symptoms, a skin prick test or blood test for specific IgE antibodies to the suspected food and co-allergens should be conducted. For non-IgE-mediated allergies, the suspected allergen should be eliminated from the diet for between two and six weeks and then reintroduced (under medical supervision).

If cows’ milk protein allergy is suspected, the mother should be provided with advice on food avoidance if she is breastfeeding, or information on the most appropriate formula or milk-substitute if formula feeding. A referral to a dietitian may be required, as may signposting to support groups. Specialist care is recommended for individuals who experience faltering growth accompanied by GI symptoms that are thought to indicate a food allergy, have had one or more acute systemic or severe delayed reactions or have not responded to a single-allergen elimination diet, or if there is suspicion of multiple food allergies (even if test results are negative).



Next, read the article on infant eczema.

Originally Published by Training Matters