England's chief medical officer, Professor Dame Sally Davies, has admitted eating hash cookies at university.
She said drug addiction should be seen as a medical problem, but that society chooses to treat it as a criminal justice issue.
Speaking on BBC Radio 3's Private Passions, Prof Davies said of her university days in the 1970s: "I never smoked so I couldn't smoke joints but I did have some cookies, until on the third or fourth occasion I had hallucinations and I've never touched it since.
"And I think I understood through that what my father said to me when I told him I was going to try it. He said: 'Drugs decivlise you. You stop being a civilised person.'
"And I understood why so many people were against even the soft drugs. So, like the fact I do enjoy wine, I'm open about my past."
She added: "Of course it's a medical problem, I mean addiction is a medical problem, and it becomes a public health problem and then our society is choosing to treat that as a criminal justice issue."
A Department of Health spokesman said: "Drugs ruin lives and cause misery to families and communities and this Government is committed to breaking the cycle of drug and alcohol dependency.
"The UK approach is to consider drug use as both a health and criminal issue and so the CMO is not saying anything new."