This information is for people who have eczema. It tells you about probiotics and prebiotics, treatments used for preventing eczema. It is based on the best and most up-to-date research.
Does it work?
It may work. Eating foods or taking supplements that contain probiotics or prebiotics in the last few weeks of pregnancy, or giving them to your baby, might reduce the chances of your child getting eczema.
What is it?
Everyone has bacteria in their gut. Some bacteria help you to digest food and kill other bacteria that are harmful. You can eat foods or take supplements that contain these 'friendly' bacteria or encourage them to grow. These are called probiotics or prebiotics.
Probiotics are live bacteria that occur naturally or are added to yoghurts, milk, some soya drinks and other foods. You can also buy them as supplements, which come in the form of tablets or capsules. 
Prebiotics are foods that encourage the growth of healthy bacteria.  They don't contain live bacteria in the same way probiotics do. In some studies, babies were given prebiotics in formula milk.
Some doctors think that probiotics and prebiotics may help our immune system to develop.
How can it help?
Taking probiotics in the last weeks of pregnancy, and giving them to the baby in the first year of life, may reduce the chances of the baby getting eczema, especially in families where eczema is common. But it doesn't cut the risk out altogether.
One summary of the research showed that the chances of a baby having eczema at the age of 2 dropped from 35 in 100 for babies who didn't have probiotics, to 29 in 100 for babies who did have probiotics. 
But taking probiotics doesn't seem to help once children have eczema.
How does it work?
The theory is that probiotics or prebiotics help our immune system to develop naturally and prevent babies becoming allergic to things later in life.
Some doctors think that the earlier the baby comes in contact with 'friendly' bacteria the better the immune system will develop in the long term. 
Can it be harmful?
None of the studies mentioned any harmful effects.
How good is the research on probiotics or prebiotics to prevent eczema?
We found one summary of the evidence (a systematic review) that looked at six studies, including more than 2,000 babies. Not all of the studies in the summary showed that probiotics worked, but when the researchers put all the results together, probiotics worked better than a dummy ( placebo) treatment. 
There are lots of different probiotics and prebiotics. It's possible that some work but not others.