BETTER late than never, but it’s a pity that the Chief Medical Officer, Dame Sally Davies, did not see fit to warn against the perils of legalising medicinal cannabis when she had the chance to stop it.

It was on the back of her hastily compiled review of the scientific evidence and recommendations that Sajid Javid made good his promise last autumn to give the all-clear for clinical specialists to prescribe cannabis oil and similar products for epilepsy and multiple sclerosis.

Dame Sally’s recommendation allowed ‘cannabis-based medicinal products’ to be ‘rescheduled’ – in effect legalised – although the evidence of efficacy from her own review was extremely limited, the problems associated with the medicalisation of cannabis were well known and the testimonial evidence that so influenced the Home Secretary fell far short of the standards required for the approval of other drugs, i.e. ‘adequately powered, double blind, placebo controlled randomised clinical trials’.

Since then medical researchers have warned against unrealistic expectations for the treatment of epilepsy.

I wrote at the time that the Home Secretary, who was under huge pressure from a highly co-ordinated media campaign and cannabis legalisation lobby, was opening a Pandora’s box. Now, as commercial cannabis traders eye the UK market and ‘marijuana doctors’ promise it as helping virtually any condition from glaucoma to autism, Dame Sally has come to recognise what they have done: ‘I think we have opened a Pandora’s box and there is a belief that it works for many conditions’. Her words now, not mine, that she used to describe the effect of this policy change to MPs on the Health and Social Care Select Committee. Patients, she told them, believe (falsely) that the drug can cure multiple conditions. Furthermore, ‘despite being recently legalised for medical use’, there was currently insufficient evidence to prove the products are both effective and safe. Now she tells us.

Ironic but welcome, not least to hear her voicing her concerns about safety: ‘THC (tetrahydrocannabinol) we know has an impact on the brain and causes depression, schizophrenia, brain development problems in young and adolescents.’ It was also welcome to hear her comment, ‘If a pregnant mother was taking it I’d be very worried.’ For good reason too. Gestational cannabis has been linked with a clear continuum of birth defects in a range of longitudinal studies, as well as increased foetal death, and reflects a worldwide increase in high cannabis-using areas. It’s high time we had full public health information about quite how dangerous (in so many ways) this addictive and therefore difficult to treat drug can be.

At least Dame Sally is now listening. Perhaps she might now encourage the Home Secretary to review his ill-considered decision.