In recent years, we’ve seen a sizeable shift in medicinal cannabis prescribing, to products containing higher levels of THC (tetrahydrocannabinol) – the component that can cause drowsiness or a high.

Now, our new study shows some of the harms with this shift, including from products containing far more THC than naturally found in cannabis plants.

We found more than half of all cases of adverse events involving unapproved medicinal cannabis products reported to the Therapeutic Goods Administration (TGA) were related to products containing higher strengths of THC.

For this group, psychiatric disorders – including anxiety, psychotic disorder and paranoia – were the most common ones reported.

Our research is released as the TGA is reviewing the safety and regulation of unapproved medicinal cannabis products. These are the more than 1,000 products that are legally available in Australia but that the TGA has not assessed for safety, quality and effectiveness.

For higher-strength THC products, particularly in some vulnerable populations – such as young people and people with mental health conditions – the increased risk of harms is a key concern.

What we did and what we found

We used Freedom of Information requests to the TGA to access more than 1,100........

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