• Smoking drug and drinking at the same time doubles risk of drink-driving
  • Also doubles risk of suffering social consequences and suffering harm
  • Was compared to only drinking or drinking and smoking, but separately
  • ‘Doctors should warn that mixing alcohol and cannabis increases risks’ 

Doctors should warn people that mixing cannabis with alcohol increases the risks, researchers said

‘If you use both substances together, your risk of drunk driving, and possibly other consequences, may be higher than if you stick to using one at a time.’

As part of the study, the researchers looked at three groups of people.

They studied those who used only alcohol in the previous 12 months, known as the ‘alcohol-only’ group.

The second group, called the ‘concurrent group’, included those who used both alcohol and cannabis but always separately.

The third group, called the ‘simultaneous group’, included those who used both alcohol and cannabis together, or simultaneously.

The researchers analysed figures from the National Alcohol Survey of more than 8,600 people aged 18 and older from all over the US.

This involved assessing differences in the demographics, alcohol-related social consequences, harms to self, and drink-driving across the three groups.

Compared to adults who solely used alcohol, simultaneous users had double the odds of drink-driving, social consequences, and harm.

Compared to concurrent users, simultaneous users also had double the odds of drink-driving.

Simultaneous users also had the heaviest drinking patterns in terms of quantity and frequency.

Dr Subbarman hopes that doctors and cannabis manufacturers will begin to warn people that smoking cannabis and drinking at the same time elevates their risk of drink driving, social consequences and harming themselves.

She said: ‘Most importantly, the findings will help clinicians and prevention/treatment specialists advise patients and others in the community regarding the elevated risk of consequences related to simultaneous use.

‘I also hope that as the cannabis industry continues to grow, manufacturers will consider some sort of warning label related to increased risks when mixing alcohol and cannabis.’

The findings were published online by the journal Alcoholism: Clinical and Experimental Research.