A peptide user regularly injected a chemical because it made her "skinny, horny and brown" - and it now seems the substance can once again be imported into the country.
The woman, in her mid-20s, who spoke to the Herald on condition of anonymity, said a $500 shipment of Melanotan II had been seized by Customs about six months ago.
She was informed it was a scheduled prescription medicine, making it illegal to import it without a prescription.
The Government's regulatory body Medsafe now concedes MTII is not a prescription medicine.
"It's not covered and we need to do something about it," Medsafe group manager Stuart Jessamine said.
Medsafe planned to restrict imports of MTII by adding it to the schedule of the Medicines Act, but more work was needed on its classification to ensure the manufacturers couldn't dodge the law by changing its chemical composition - as happened when MTI was replaced by MTII.
MTII was one of five classes of peptide - many of which are used by sportspeople as performance enhancing drugs - the importation and use of which Medsafe is attempting to control.
None had passed clinical trials and they weren't considered safe for human use, Mr Jessamine said.
"I can't tell you if they have got long term or even short term side effects. There hasn't been any significant research done on many of them. Our advice would still be 'don't go near them with a barge pole'," he said.
The woman plans to continue to import and use MTII.