Scientists are calling for a major effort to make cannabis use less harmful as a rising number of countries look to replace long-standing and outright bans on the drug with more relaxed legislation. Researchers at King’s College London and UCL said it was now crucial for health officials to consider measures to reduce the harm from cannabis use. Many of the health risks that users face could be reduced by discouraging people from smoking it with tobacco, and using vapourisers instead, according to an article in the journal Lancet Psychiatry. Another option the scientists propose is to boost levels of CBD in high potency cannabis, so that users can get their hit without being at such risk of mental harm.