Jeremy Laurance: Believe it or not, there are worse things than mephedrone

One of the best pieces of advice I received as a parent of teenagers was from a friend who worked in a home for kids who had been in trouble with the law. "You can't stop them going at 100 miles an hour," he said. "The best you can hope for is to stop them going at 150 miles an hour".

That phrase echoed in my head for the best part of a decade as I faced, like every parent, the disputes, debates and disagreements common to every household where adults are struggling to keep the lid on things and kids are determined to blow it off.

It was a reminder that seeking to be the perfect parent is simple folly. The best you can hope for is to be a good enough parent, and if you curb your ambition you will probably end up doing a better job than if you strive for perfection.

It came to mind again this week in the row over mephedrone. In our anxiety, as parents, to protect our children we have become transfixed over the legal status of one drug. Never trust anything people say in the middle of a drug panic. I heard one, understandably agitated, parent claim on Radio 4's Today programme that it was the most addictive substance around – according to his son, who was a user. This meaningless claim went unchallenged. As a World Health Organisation committee pointed out almost half a century ago, "there is scarcely any agent which can be taken into the body to which some individuals will not get a reaction satisfactory or pleasurable to them, persuading them to continue its use even to the point of abuse."

It recalls the panic over ecstasy 15 years ago when Essex teenager Leah Betts died, allegedly from the toxic effects of half a tablet of the drug at her 18th birthday party. As drug experts said at the time, no drug of abuse can kill in such a dose – but their opinion was drowned out in the ensuing public hue and cry.

For parents trying to rein in teenagers determined to experiment, the challenge will remain the same – how to stop them going at 150 miles an hour. Whether mephedrone is legal or illegal may make a difference at the margins – though isn't forbidding an activity as often supposed to increase its attractiveness as reduce it? – but will not alter the landscape.

The message, for any sane parent, surely has to be this: you can't stop your children experimenting, for that is what growing up is about. The most you can hope for is to reduce the risks. That means having a grown-up conversation not only about illegal drugs (don't drink litres and litres of water after downing a tab of ecstasy as Leah Betts did, which is what ultimately killed her by causing swelling of her brain) but also about the legal drugs, alcohol and tobacco. They cause harm orders of magnitude greater than all illegal drugs put together. And as we know, "addiction" – or habituation – begins for the vast majority in the teenage years.