A gravely-ill Nelson teenager at the centre of a cannabis debate appears to be making progress - he's now breathing on his own.

Alex Renton, 19, has been in an induced coma in Wellington Hospital for two months, after suffering a seizure.

Earlier this week Associate Health Minister Peter Dunne approved a one-off use of cannabis oil because nothing else has worked for his family.

The teen's mother Rose Renton said her son is stable and much stronger than last week.

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Alex was now breathing on his own and much stronger than last week, she said.

The cannabis oil has yet to be administered, she said, and the family was still waiting the specially-approved dose.

The treatment should start today, and she said they would know more after he's had a weekend of the medicine in his system.

- NewstalkZB