While exclusive breastfeeding of babies - whose mothers have an allergy - protects them in early childhood, it actually increases the risk of them developing allergies as adolescents and adults, according to a study done by the Melbourne University's School of Population Health.
Breastfeeding offers no protection from allergies among children without a family history of allergies, says the study.
Babies who were exclusively breastfed in the first three months had a reduced risk of developing asthma or food allergies by the age of seven.
However, this risk reversed as they got older and by the time they had reached 14, 32 and 44 years of age, they were at increased risk of having asthma, food allergies or hayfever.
Using data from more than 8500 people from the 36 year follow-up of the Tasmanian Longitudinal Health Study the research is the first in the world to follow subjects from childhood into middle age.
The project is a collaboration between the University of Melbourne, Monash University and the Menzies Research Institute in Tasmania.
"The effect of breastfeeding on the risk of contracting allergic diseases has been controversial in recent years, and while there have been many studies few have followed the subjects into adulthood and none into middle age,'' Dr Matheson, lead author, said in the US-based Journal of Allergy and Clinical Immunology.
"The aim of our study was to examine the effect of exclusive breastfeeding in the first three months of life on the risk of current asthma and allergies throughout childhood and into middle age."
Dr Matheson said the research confirmed the current recommendations that high risk infants - those whose mothers had an allergy - should be exclusively breast-fed to protect against wheezing illness in small children.
However, recommendations that babies be exclusively breastfed to protect against asthma and allergy in the long term should be reconsidered.
Dr Matheson said further investigation was needed to determine why there was an increased risk of developing asthma after seven years of age.
"It could be that mothers are passing antibodies on to their babies or because of increased hygiene and reduced exposure to infections early in life,'' she said.
"The breastfed children in our study had fewer bacterial and viral infections, were more likely to be first born and in a higher social class - these all factors related to increased hygiene."
Dr Matheson said the study's authors acknowledged there were many benefits of breastfeeding and were not suggesting that women with allergies should not breastfeed.
"However, if you are concerned about preventing allergy in your children, it may be more effective to implement other strategies such as not having carpet in your home,'' she said.