Parents should avoid using household teaspoons to give children medicine as sizes can vary widely, leading to both under- and overdoses, a study warns.

US and Greek researchers looked at teaspoons in 25 households and found that the largest was three times the size of the smallest.

They also found that when asked to use 5ml medicine spoons, people poured in varying quantities.

To avoid dosage differences, the team urged parents to use syringes.

The study in the International Journal of Clinical Practice looked at more than 70 teaspoons collected from 25 homes in Greece.

Low risk

The team from the Alfa Institute of Biomedical Sciences in Athens suggested that a parent using the largest domestic teaspoon would be giving their child nearly three times as much medicine as the smallest.

Most households in the study had between one and three different teaspoons, but two women had six.

"We not only found wide variations between households, we also found considerable differences within households," said Professor Matthew Falagas, the lead author.

In addition, when they asked five people to measure out medicine in a calibrated 5ml spoon, they found that only one gave the correct dose.

Syringes are increasingly given out with over-the-counter medicines such as child paracetamol and ibuprofen.

The risks of harm occurring as a result of parents giving too much of these products in a single dose is thought to be very small indeed.