Mephedrone has emerged as "the substance of choice" among young drug takers on Orkney, according to police.
A report to the Northern Joint Police Board said several people were thought to have become unwell on the islands, but not sought help, after taking it.
Previously known as a legal high, mephedrone was reclassified as a Class B substance in April.
Mephedrone with a street value of more than £7,000 was also seized in the Inverness area, the report said.
The details are contained in a report by Chief Constable Ian Latimer on crime activity between April and June in the Northern Constabulary force area.
In the paper to Friday's board meeting, he said: "In April and May mephedrone emerged as the drug of choice with young drug takers in Orkney."
The seizure of mephedrone was among 418 drug offences dealt with in the Inverness, Badenoch, Strathspey and Nairn area command.
Mr Latimer said the high number of offences was mainly due to June's RockNess music festival at Dores.
In April, Inverness-based Highland Homeless Trust said illegal drugs were "readily available" across the north of Scotland.
It said heroin, cocaine and crack cocaine were the most common addictions.
But director Dr Paul Monaghan said mephedrone was also starting to have an impact on the Highlands.