They are sold in our pharmacies, not on our street corners

More people die from taking painkillers than from taking heroin.

This does not mean that heroin is safe. It means that painkillers are dangerous and a lot more people take them than take heroin.

There is a problem - as Gordon Brown found out when looking at re-classifying the level of danger from using Cannabis - with talking about the dangers of drugs.

In terms of risk of death, the three most dangerous 'drugs' in our society are all legal.

In the UK, nicotine kills three hundred people a day, sugar kills two hundred people a day and alcohol kills one hundred people a day.

All the illegal drugs together kill fewer than fifty people a day. This does not mean that they are safe. It means that fewer people take them.

If all the people who drink or smoke were to use heroin, there would be considerably more deaths from heroin.

That would not make it a more dangerous drug in terms of mortality risk. The level of risk would be the same for a greater number of people.

Pharmacologically, heroin is a relatively safe drug. It is nothing like as poisonous to the body as alcohol. Its risks often come from overdose or from the use of contaminated needles.

This gives rise to the concept of 'harm reduction', by which 'safe' use and clean needles are seen as sensible approaches to the problem of addiction.

I believe nothing of the kind. The most effective form of harm reduction is total abstinence from all mood-altering drugs, including alcohol (look what happened to Amy Winehouse) and regular attendance at Narcotics Anonymous.

Methadone is prescribed as an alternative to heroin. It is given as a liquid so that it is swallowed rather than injected. This reduces the risk of transferring HIV via dirty needles.

There is also a risk of Hepatitis B and Hepatitis C and other illnesses being caught in the type of environment in which heroin is commonly used.

The overall risks are therefore not simply those of a drug itself but also of the way that it is taken and the environment in which it is taken.

Methadone is a dangerous drug because it often kills in overdose. The Department of Health likes it because it reduces the risk of HIV and crime.

Except that it doesn't do so to any significant extent. It is estimated that fifty percent of people taking Methadone also take daily - daily - heroin and many of the rest also use it occasionally.

There is a black market in Methadone. Some addicts prefer it to heroin.

There is even a black market in 'spit' Methadone, when the liquid is kept in the mouth after being given under supervision and then spat out into a bottle.

Medicinal treatment for diseases of the human spirit - addictions and compulsions and depression -  are fraught with physical and psychological dangers.

Medicinal treatment should be the last, rather than the first, resort.

As for painkillers, they are vastly over-prescribed and also bought excessively over-the-counter in pharmacies. It is high time that this danger should be highlighted.

Today I had surgical injections into the facet joints of my lower spine. I know about persistent pain. I've had it for eighteen months and I don't like it.

But, throughout that whole time, except right at the beginning after the acute collapse of a vertebral body, I have not taken pain-killers. They're dangerous. Years ago I took them for one day when I had gallstones and for two days when I had kidney stones.

But mostly I think it is safer to live with some level of pain rather than to take drugs of any kind.

Drugs - all mood-altering drugs, even those that come from a sympathetic doctor rather than from a dealer - are dangerous.