There is an enzyme in the bowels which breaks down the sugar in breast or formula milk. However, sometimes this enzyme isn't present - if a child has had a stomach upset, for example - and then the body does not know how to manage this lactose in the milk.
What are the symptoms?
A baby who has a lactose intolerance will be very windy and possibly sick. She will also have stomach pains which make her cry for prolonged periods, and she may have diarrhoea.
What should you do?
If you think your child may be having this reaction to any milk, contact your doctor, who can organise for tests to be done on your baby's bowel movements.
When your baby is allergic to milk
It can be possible to have an allergic reaction to milk even though formula is specially made for young stomachs and breastmilk is 100 per cent natural.
In a breastfed woman, this is caused because the milk and other dairy products the mother eats are passing on the irritating protein through breastmilk.
Allergic reactions to milk can include rashes, being sick, colic, eczema and rashes which are similar to allergic reactions of other kinds.
A child will most likely grow out of this allergy.
What can be done about milk allergy?
If breastfeeding, the mother is advised to cut out dairy products from her diet and find other sources of calcium and protein.
If you are giving your child formula, you doctor might ask you to try a formula milk which contains no cow's milk protein.
The problem should right itself quite quickly but it is advisable to monitor the growth of your baby to ensure she is taking in sufficient goodness while you get to the bottom of the problem.