Editor’s note: The headline has been updated. It previously stated that Professor Renee Bittoun was a medical doctor, but this was incorrect. She has a PhD and is an internationally renowned nicotine addiction and smoking cessation expert.

“I have seen young people present to my clinic who find it incredibly hard to go two hours without vaping.”

Professor Renee Bittoun, who has worked in smoking cessation since the 1970s, never expected to see so many children and teenagers with nicotine dependency.

But thanks to the explosion in disposable e-cigarettes, underage patients — many with “significant” withdrawal symptoms — are a regular sight at her Sydney clinic.