The overprescription of antibiotics isn't just leading to drug-resistant superbugs - it could also be behind the growing allergy epidemic afflicting the world's wealthiest societies.
Scientists have found links between the use of antibiotics in the first two years of life and allergenic conditions like hay fever and eczema.
Researchers in the Netherlands looked at data from 44 studies conducted between 1966 and 2015, involving about 650,000 patients.
They found increased risks for both eczema and hay fever between 15 and 56 percent, depending on the type of study.
The link was stronger if the infant patient had been prescribed more than one course of antibiotics.
"Early life exposure to antibiotics is related to an increased risk of both eczema and hay fever later in life," concluded head researcher Fariba Ahmadizar of Ultrecht University.
The findings back a growing consensus that exposure to microbes early in life plays an important role in developing the body's immune system, called the 'hygiene hypothesis'.
It follows New Zealand research earlier this year which found children who bite their nails and suck their thumbs are less likely to go on to develop allergies.
And in May, scientists in Finland released a study showing allergies were much more pronounced in wealthier communities with better sanitation than neighbouring poorer areas.
The latest research will be presented today at the European Respiratory Society International Congress in London.