What is cow's milk allergy?
Cow's milk allergy is an allergic reaction triggered by a protein in cow's milk. Like any allergic reaction, it represents an abnormal response by the immune system to a specific protein. It is one of the most common allergies in babies, some studies suggesting that up to 7% of infants may suffer from it.
Cow's milk allergy should not be confused with lactose intolerance, another common milk-related problem in which the sufferer may lack an enzyme needed to digest milk sugar. Many babies who are allergic to cow's milk eventually outgrow the problem. However, lactose intolerance tends to worsen as children get older. Many babies develop it as a temporary condition lasting for just a few weeks after a bout of gastroenteritis.
What causes cow's milk allergy?
Any allergic condition is the result of an over-reaction of the immune system, which normally protects the body from outside invaders, such as viruses or bacteria. Special cells produce antibodies that attack specific proteins identified as potentially harmful. In an allergic reaction, however, these antibodies seek out proteins in normally harmless substances known as allergens, such as a protein in cow's milk. A baby with cow's milk allergy can tolerate breast milk, but when fed a formula containing cow's milk, it triggers a sequence of events that results in the allergic response.
Symptoms In babies:
In older children:
How is cow's milk allergy diagnosed and treated?
Symptoms such as a rash, diarrhoea, or blood in the stools should raise suspicion of cow's milk allergy, especially if they occur after a baby has been switched from breast milk to a bottle. The allergy usually shows up after a baby is put on a formula feed containing cow's milk proteins. In most cases, it disappears on its own by the time the baby is 1-2 years old.
The diagnosis can be confirmed if the symptoms disappear after cow's milk is eliminated from the baby's diet, then reappear when the baby is given a trial feed containing cow's milk protein.
Treatment consists of replacing cow's milk formula with one that does not contain these milk proteins. After the age of six months, some babies can tolerate milk from other animals such as goats. More often, the baby will be transferred to a soya formula.
What can I do myself?
By giving a baby only breast milk for the first few months of life, you can often prevent cow's milk allergy from developing. Babies who are not exposed to cow's milk for the first 6-9 months of life are not as likely to develop cow's milk allergy as those who are given it at an earlier age.
If there is a family history of allergies, some pediatricians advise women to avoid drinking cow's milk both while they are pregnant and
while breast feeding, so that the baby will not be exposed to cow's milk proteins at the age when most likely to develop antibodies against them.
When should I see my doctor?
If your baby is consistently experiencing diarrhoea, vomiting or passing blood in stools you should visit your doctor.
You should also see a doctor or health visitor if the baby does not seem to be growing normally, or begins to lose weight after changing to a formula using cow's milk proteins.
What will the doctor do?
Your doctor will examine the baby and check to see if growth rate has been normal. You will be asked about feeding patterns and episodes of diarrhoea, vomiting and other symptoms. If cow's milk allergy is suspected, cow's milk will be substituted with a soya formula, which is available from chemists and may be obtained on prescription. The symptoms usually disappear almost immediately.
To confirm the diagnosis, the baby may then be given a 'challenge feeding' of cow's milk to see if the symptoms return. If so, it is clear that the problem has been correctly identified as cow's milk allergy and the baby should not be given cow's milk until the age of 18 - 24 months.
For those infants who remain allergic to cow's milk beyond the age of two, a dietitian or doctor will be able to advise on which foods to exclude. In addition to obvious milk-based products, cow's milk may be present in bread, soups, cereals and instant mashed potato. The key ingredients to look out for on food labels are casein, lactose and whey, although hydrolysed casein should not cause an allergic reaction.
Is cow's milk allergy dangerous?
Not usually. However, it may affect the baby's growth rate; and frequent bouts of vomiting and diarrhoea can weaken an infant and increase susceptibility to infections and other illnesses.
Do not exclude milk or milk products from your child's diet without medical supervision by a doctor or qualified dietitian. There may be a risk of nutritional deficiencies.
Ordinary cow's milk, as opposed to bottle or formula milk containing cow's milk proteins, should never be given to babies under six months old.
It contains high levels of sodium and potassium which immature kidneys cannot cope with. Ordinary cow's milk also contains proteins which infants are unable to digest.