Vapes will only be available from behind the counter at pharmacies under changes to stop younger generations being hooked on nicotine.

Reforms coming into effect from Tuesday will allow people able to buy vapes from chemists without a prescription, but users would need to speak to a pharmacist before buying.

The vapes will also come in plain packaging and flavours will be limited to mint, menthol or tobacco.

Health Minister Mark Butler said the changes would help to stop more young people becoming addicted to vaping.

"The days of bubblegum-flavoured vapes covered in rainbows and unicorns are over. The cynical marketing to our children is done," he said.

"The only lawful way to purchase a vape is through a pharmacy."

The changes coming into effect follow laws that kicked in from July that banned the sale of vapes outside of pharmacies.

In September, Mr Butler said a more assertive approach was needed to crack down on illegal suppliers of vapes, with some tobacco and convenience stores continuing to sell the product.

Penalties of up to seven years in prison and fines of $2 million apply for those illegally supplying or manufacturing vapes.

Vape buyers would need photo ID for age verification.

The health minister said a crucial aspect of the reform would be pharmacists having "important conversation around the health harms of vaping".

Mr Butler said pharmacists had been given extra guidance on dispensing vapes.

"Importantly, pharmacists will have automatic insurance coverage when supplying vaping products for smoking and nicotine dependence," he said.

"Therapeutic vapes will have similar restrictions to other pharmacist-only products like pseudoephedrine, allergy and asthma medications."