Cases of legal high-related hospital admissions have doubled in Scotland in the last two years, new figures show.
Since 2009 more than 320 people have been admitted to hospital after consuming the drugs, according to figures from NHS Scotland.
One expert has said experimenting with legal highs – sometimes advertised as plant food or bath salts – is like “dancing in a minefield”.
According to the statistics, 139 admissions were recorded in 2013, compared with 61 the year before.
The figures were obtained by the Conservatives in Scotland, who called for action to tackle the problem.
The Government said it was working to better understand Scottish legal high issues.
Conservative health spokesman Jackson Carlaw commented: “This is clearly a problem that is getting worse, and we need a plan of action to tackle it.
“Even from these statistics it’s obvious the issue is becoming more prevalent.
“But, without all the health boards collecting the relevant data we will never know the true extent of it.”
A Scottish Government spokeswoman said recording the prevalence and use of legal highs – or new psychoactive substances (NPS) – was difficult.
She said the Government would be “commissioning research on NPS in Scotland to understand more about the scale of this issue and who is using these substances and why”.
“This builds on the work that we have been taking forward to improve national data collection tools to provide more information on the use of these substances”, she added.
Earlier this month a UK-wide report found that deaths caused by legal highs have risen by almost 600 per cent in three years.
Professor Fabrizio Schifano, a spokesman for the group which released the report, said: “Clearly this is a major public health concern and we must continue to monitor this worrying development.
“Those experimenting with such substances are effectively dancing in a minefield.”