The pill is designed to exploit the placebo effect
A fruit-flavoured sugar pill which parents can use to soothe childhood aches and pains has been criticised.
The pills are already on sale in the US, costing $6 for a bottle of 50.
They harness the "placebo effect", which makes some people feel better because they falsely believe they have had medicine.
One UK scientist said it could make children rely on pills later in life, and another accused the makers of "medicalising love".
Although US doctors are forbidden from prescribing a placebo for their patients, there is nothing to stop the pills being marketed as a health supplement.
Jennifer Buettner, whose company "Efficacy" makes "Obecalp" - placebo spelled backwards - said that there were plans to market the pills in the UK.
She said they stimulated the body to "heal itself".
However, Dr Douglas Kamerow, an associate editor of the British Medical Journal, said that it was a "deeply bad idea".
When children grew old enough to realise they had been deceived, he wrote, it could damage the trust they have for their parents.
He added: "If parents use placebos to comfort their children, what are they teaching them? That tablets are the answer for all our aches and pains, and perhaps all our other problems too? Not advisable.
"I don't buy the argument that giving a child a placebo pill is just like putting a plaster on a scratch.
"Sure, there are kids who end up wanting a very colourful plaster for every possible ache and injury, but I have never seen an adult addicted to plasters - although I've have seen very many adults who want a pill for every ill."
Dr Clare Gerada, from the Royal College of GPs, said that the pill "medicalised love".
"It is telling them that unless you give your children this pill, there's nothing else."
Jayne Lawrence, chief scientist at the Royal Pharmaceutical Society of Great Britain, said: "As a dietary supplement, the manufacturers have not been required to carry out clinical trials.
"Further, the use of this drug indicates that symptoms diagnosis and advice have not been sought from a qualified healthcare professional, which runs the risk of misdiagnosis.
"We are also concerned that giving a child the pill reinforces the wrong
message - that tablets are the answer for all of life's aches and pains."