Only two things are clear in the Home Office move to allow access to cannabis for health reasons: you won’t be allowed to smoke a joint and the home secretary is adamant the new policy is not a step towards allowing access to cannabis for pleasure. But this still leaves a lot of issues unclear.

For example defining exactly what a “cannabis-based medicinal product” is has proved to be tricky. The Home Office asked its scientific advisers the Advisory Council on the Misuse of Drugs (ACMD) to help draw up a definition. The ACMD responded by raising concerns about the interim definition proposed by the Home Office as it does not include safety or quality standards. This means cannabis-based products might circumvent the regulatory scrutiny that other medicines have to go through before they are made available.

But beyond these technicalities the line between recreational and medicinal use is not an easy one to discern. One person’s need to feel different is another’s desire to self-medicate. Cannabis is used by many to relax, think or experience feelings that they don’t usually have without ingesting the drug. To some extent all drug use including cannabis is a form of self-healing whether we describe this as pleasure even when it is obvious to others it is a way of escaping boredom, stress or countering social anxiety. For some cannabis exacerbates ill health particularly mental health, the problem is that we still can’t predict who will be helped and who will be hampered when using cannabis.

No policy is perfect but constructing one that hits a sweet spot between risk and benefit, protecting the vulnerable while not curtailing appropriate access is ambitious. The home secretary has called for the policy on cannabis to be informed by evidence but paradoxically decades of restricting researchers’ access to cannabis due to its legal scheduling have put off even the most determined research groups from investigating the drug’s therapeutic potential.

Research carried out mainly in other countries suggests there are potential health benefits of cannabidiols (CBDs), a component of cannabis, for some health conditions but much of this research is limited to either animal studies or studies which are of limited value. Most people won’t have access to this research and instead are exposed to wild claims about the ability of cannabis products to cure all sorts of conditions including cancer. So those who are at a really vulnerable point in their lives are given false hope. This is compounded by a mismatch between the dose of cannabidiols used in research and many of the cannabis products being marketed. These contain such low doses of CBDs that they are homeopathic or at best produce a placebo effect, that might be enough to work for some but won’t produce the results found in studies where doses can be 10 times stronger.

It is GPs who will be left to manage these expectations, as they will be the first point of contact in this new system to access cannabis products. It will be a year before the National Institute for Health and Care Excellence produces clinical guidance, in the interim NHS England has provided doctors and patients with some details about the process of access rather than evidence of which cannabis products are effective for specific conditions. What’s needed is a reliable and easily accessible source, such as an app that both groups can turn to.

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We also need to learn from the American experience where several states have allowed access to cannabis for health reasons via an individual’s physician. There are concerns that this policy has resulted in patients and doctors playing the system where a nod and a wink between both parties facilitates access to cannabis. This is unlikely to happen in the UK as the process for accessing medicinal cannabis looks overly restrictive compared to obtaining street cannabis.

Despite the home secretary’s assertion that this new policy does not pave the way to allowing recreational use of cannabis I’m not convinced. This policy change was triggered by the personal story of Billy Caldwell, a young boy with a severe form of epilepsy helped by a cannabis-based product. So while personal stories like Billy’s can nudge policy, it is commercial interests that really have the ability to trigger and shape policy.

There is substantial speculative money and time being invested in opening up access to cannabis in the UK. Over the past couple of years I have been approached by an increasing number of investment bankers, entrepreneurs and companies involved in the production of cannabis and I’m only an academic not a politician. With this in mind and knowing that the public supports the idea of allowing access to cannabis for recreational use I think the Home Office is testing the water by allowing medicinal access as an incremental policy shift towards opening up access.