Smoking a spliff is not what it used to be – or so I am told by friends who would opt for a joint rather than a glass of red to help them wind down after a stressful day at work.

The reason for their increasing lack of interest is not reflected in the latest report by the Home Office, but to these average dope smokers the simple answer to why they don't smoke as much any more can be summed up in one word – "skunk".

Five years ago skunk, a type of cannabis three to four times stronger than traditional "grass" and resin, accounted for just 30 per cent of the market, now it accounts for more than 80 per cent. Only a month ago the Advisory Council on the Misuse of Drugs said that skunk is likely to have long-term health risks, including a significantly higher risk of developing schizophrenia.

My own experience with skunk is anything but pleasant. At a party a few years ago I was offered a spliff (and yes I did inhale) thinking it was run-of-the-mill grass but what the person who offered it to me failed to mention was that it was skunk. Instead of getting the giggles after a puff my skin went pale, I felt faint and within minutes I was in the toilet throwing up.

This "whitey" experience is one shared by most of my friends, some who smoke occasionally but others who by their very own admission are potheads. These days they all complain that it is nearly impossible to find a dealer who sells ordinary grass or resin instead of skunk, and if they do find one who sells it then the product is so expensive that they treat it as a vintage bottle of wine – only to be consumed on very special occasions.

At least two people I know have been diagnosed with depression and schizophrenia which their doctors attributed to their habit of smoking dope and especially skunk. The sadness of seeing bright and happy friends turned into emotional wrecks now living at home with their parents unable to work is enough for me not to be tempted to touch the drug.

I strongly feel that upgrading cannabis to a Class B drug was the right thing to do purely for the fact that skunk transformed what was a somewhat harmless vice into something much more dangerous.