Children aged under 15 should never be given alcohol, even in small quantities, England's chief medical officer has advised parents.
Sir Liam Donaldson said childhood should be an "alcohol-free time", as ministers prepare to publish guidance on the issue for the first time.
He told BBC News children who drink were at risk of "serious harm".
It is legal for parents to give a child over five alcohol in the home and the guidance is not expected to become law.
The guidance is published after the CMO's team reviewed the medical evidence on the effects of under-age drinking.
It comes after a recent survey suggested 20% of 13-year-olds drank alcohol at least once a week.
The guidance also says children aged 15-17 should not be given alcohol on more than one day a week - and then only under supervision from carers or parents.
Sir Liam told the BBC the practical advice was a direct response from parents who wanted information on the health effects of giving children alcohol.
"It is advice to parents. It's their choice at the end of the day within the family setting," he said.
"There is serious harm that can come to children if they drink and the main advice is that childhood should be an alcohol-free time. Certainly under the age of 15 there are serious risks."
The advice is the first on children and alcohol produced by the government, but it is understood there is no intention to back it with legislation. The public will be asked its views during a three month consultation period.
Ministers and doctors are worried by rising rates of binge-drinking and alcohol-related liver disease in the young and see the guideline as a necessary step in preventing people getting a taste for alcohol at too young an age.
'Pocket money prices'
However, some parents, and researchers, have argued that giving a child an occasional drink helps demystify alcohol, and reduces the chance of bingeing later on.
Damion Queva, publisher of Fathers' Quarterly magazine, told the BBC he had given his daughter a small glass of champagne and orange juice on her 13th birthday.
"Teenagers shouldn't be drinking but in the real world it happens and they are going to get it elsewhere.
"Parents can take control by taking the mystique out of it by giving them a taste and educating their children about alcohol and abuse of alcohol."
'Drinking every day'
Ali is 16 but had his first drink at 10. He told the BBC he has been working with the Glaciere Project in Liverpool for 18 months, which helps children give up drinking by teaching them sailing and scuba diving.
He's also stopped drinking: "I was hanging around with a lot of older people and they gave me the drink and I progressed further.
"I was just getting myself into trouble. It just became a part of every day that you would have a drink."
Professor Ian Gilmore, the president of the Royal College of Physicians and chair of the Alcohol Health Alliance, said: "Alcohol is a drug; it's a drug of addiction.
"There's some evidence that youngsters who taste it early are more likely to become alcohol dependent in later life.
"One mustn't lose sight of the fact that alcohol is the biggest cause of death in young men aged 16-24.
"I think one of the key recommendations is that there should be parental supervision between 15 and 17 years of age - we know every year young people die from alcohol poisoning."
The Liberal Democrat health spokesman, Norman Lamb said: "We have to focus on getting the message across about the potential health risks of excessive alcohol consumption.
"However, we must be careful to support parents who are giving sound advice to their children and not undermine their judgement."
But the social care charity, Turning Point, said: "What is being overlooked today is the fact that one in 11 children, often living in some of our poorer communities, are more likely to go on to have devastating alcohol and emotional problems because of parental alcohol misuse.
"At the moment there is simply not enough help for children and families affected by alcohol misuse."
Wales' CMO Dr Tony Jewell said he would await the outcome of England's consultation before issuing any guidance.
In Scotland and Northern Ireland information and advice for parents is due to be issued shortly.