Talking to patients about cannabis medicine: what actually helps

The first follow-up consultation is, in my view, where cannabis medicine is really shaped. I do not carry out initial assessments myself, so by the time a patient reaches me they have already been started on a product and have formed their first impressions of it. Some have been using cannabis illicitly for years and arrive looking for validation. Others are deeply sceptical, having been referred reluctantly after running out of other options. Either way, this is the conversation where expectations meet reality.

What I have learned through repetition more than any formal training is that the quality of that follow-up conversation shapes almost everything that comes after.

Common misconceptions

Almost every patient arrives with at least one of two beliefs: that stronger is better, or that CBD does not do anything.

The second one is understandable. Patients given a high-CBD, low-THC product often feel little or nothing and conclude it is not working. CBD does not produce a noticeable psychoactive effect, and in a culture where the perceived measure of cannabis working is a feeling of being high, a medicine that works quietly in the background can seem like no medicine at all. But the absence of a noticeable effect is not the same as the absence of an effect. CBD acts on a wide range of receptors and pathways, and its benefits in anxiety, inflammation, and pain regulation can be real without the patient feeling anything dramatic.

Anxiety and depression

This is where I have some of my most important conversations. High-THC products can feel very effective for anxiety and depression in the short term. They take your mind off your troubles, create a sense of relaxation, and feel good in the moment. Much the same as half a bottle of wine.

But this is not a healthy way of managing mental health. High THC overstimulates CB1 receptors, and over time this leads to tolerance and an increased risk of dependence. PET imaging studies have shown this directly: in chronic daily users, CB1 receptor availability drops by around 15 to 20%, and the degree of downregulation tracks with how many years a person has been using (Hirvonen et al., 2012). The body compensates by turning down its own endocannabinoid signalling, which can actually worsen anxiety and low mood between doses.

I draw an analogy with antidepressants. Antidepressants do not make you feel happy or relaxed in an obvious, immediate way. They work slowly, in the background, restoring balance. Medical cannabis used for anxiety and depression should work similarly. If a medicine is making you feel stoned or euphoric, that is not a sign it is working well. That is a sign the dose and ratio need reviewing.

I am clear that there is a legitimate place for recreational cannabis use, and I am broadly supportive of harm reduction approaches given what we know about alcohol. But if someone wants to genuinely manage their anxiety or depression, we should be working to restore balance in the endocannabinoid system, not to mask symptoms with a sedating high.

The good news is that tolerance reduces relatively quickly, usually over two to four weeks. By restarting low and slow, patients can still experience the acute relaxant effects of cannabis while allowing their endocannabinoid system to recalibrate. That is a far more sustainable position than chasing an ever-higher dose for a diminishing return.

The long-term user conversation

Some of my most experienced patients arrive convinced that years of use have earned them a permanent need for the highest available THC. The logic seems sound: long-term use, high tolerance, therefore maximum strength is justified. It is one of the most common positions I encounter, and it is worth gently challenging.

The evidence here is genuinely reassuring. The same PET imaging work showed that while CB1 downregulation correlated with the number of years a person had used cannabis, those receptors still returned to baseline after around four weeks of abstinence (Hirvonen et al., 2012). In other words, even many years of heavy use does not appear to cause permanent tolerance. The system is remarkably resilient and willing to recalibrate when given the chance.

This reframes the conversation. A patient who believes they are stuck needing the strongest product available is, more often than not, simply carrying the accumulated tolerance of continuous use. That tolerance is not a fixed feature of who they are. It is a reversible state, and a planned tolerance break or period of reduction can restore much of the sensitivity they thought they had lost for good.

Panic disorders

High THC does have a genuine role in panic disorders, and this is one situation where I explain its mechanism quite differently. In my clinical experience, during an acute panic episode a high-THC product can produce a sudden and significant shift in mental state that effectively aborts the spiral. Think of it like a glass of water in the face: sharp, sudden, and disorienting enough to break the cycle. The patient then settles back to a more balanced state over the following hour or two.

This is quite different from using high THC as a daily anxiolytic, and I make sure patients understand the distinction.

Pain

High THC has a clear place in pain management, but the same tolerance dynamics apply. With repeated high-dose THC use, CB1 receptors become saturated and tolerance develops, so doses creep up while effectiveness falls. CBD may help here too: it acts as a negative allosteric modulator at the CB1 receptor (Laprairie et al., 2015), which means it changes how THC engages the receptor, and it may help limit some of the receptor changes that drive tolerance, although the details are still being worked out.

One approach I find useful for patients who genuinely require high doses is to rotate cultivars regularly. Changing cultivar shifts the terpene profile and, just as importantly, the profile of minor cannabinoids in the product. These minor cannabinoids matter more than their small quantities suggest. They can influence how THC interacts with the cannabinoid receptors, interact with those receptors in their own right, and alter the metabolism of THC and other cannabinoids. The evidence for these interactions is still developing and somewhat contested, but the pharmacological rationale is sound.

The practical effect is that rotating cultivars can rejuvenate effectiveness, sometimes even when reducing the THC strength or holding it steady. It is a more sophisticated strategy than simply increasing the dose, and it fits with the chemovar-based thinking I have written about elsewhere.

The broader point is that patients on high-THC pain regimens need regular review. Tolerance breaks, ratio adjustments, cultivar rotation, and bringing CBD into the regimen are all worth discussing early, rather than waiting until the patient reports the medicine has stopped working.

References

Hirvonen et al. 2012. Reversible and regionally selective downregulation of brain cannabinoid CB1 receptors in chronic daily cannabis smokers. Molecular Psychiatry.

Laprairie et al. 2015. Cannabidiol is a negative allosteric modulator of the cannabinoid CB1 receptor. British Journal of Pharmacology.