An advertising campaign was launched by the government on Monday to warn children and young people about the health risks of cannabis. The £2.2m Home Office campaign's target audience is the 11 to 18 year olds and the drug is being reclassified as a class B drug from the less serious C category it currently is in. The campaign will reach audiences through advertisements using TV, radio and the internet and the drugs side effects of memory loss, paranoia and panic attacks are being highlighted.

"Cannabis is a destructive drug. What can start as a few giggles and being part of the crowd can have serious and long-term health problems," Public Health Minister Dawn Primarolo said.

"Young people need to know cannabis isn't a soft drug. They need to be aware of the risks they're taking."

With cannabis coming under class B rules, it comes alongside amphetamines and barbiturates and users of the drug face up to five years in jail while the drug suppliers a maximum of 14 years. Under its current classification anyone caught in possession of the drug is given a warning, the second offence carries a fine and the third prosecution.

Cannabis is the most frequently used illegal drug by children aged 11 to 15 and according to Home Office figures almost 18 % of 16 to
24 year olds and more than 7 % of people between 16 to 59 use the drug.

Louis Appleby, the national director for Mental Health Services said, "We have known for years that it can be part of a pattern of relapse and risk in people with severe illnesses such as schizophrenia and bipolar disorder. Now the evidence is pointing to cannabis as the cause of psychosis in some people, particularly people who are heavy users."

Marjorie Wallace, chief executive of mental health charity Sane said, "We need hard-hitting campaigns like this to convince people just how frightening the effects of cannabis can be. For those who are vulnerable, taking it may not be just chilling out for an evening but could mean robbing themselves of their chances in life."