More than 1,400 people have been admitted to hospital after taking performance enhancing drugs in the last four years, new figures show.

Stimulants included anabolic steroids, used to help build muscle, caffeine stimulants which are popular with students studying for exams, diuretics and the cosmetic drug botox.

But there were warning that the numbers represent only the "tip of the iceberg" after some data was found to be missing.

The substances are known collectively as "performance or image enhancing drugs" (PIEDs).

Experts warn that the stimulants are involved in around one in 10 people who seek help for addiction.

Many of those admitted to hospital were under the age of 18, according to the new figures, while in NHS Grampian, there were instances of patients being admitted following "abuse of herbal of folk remedies", according to the figures.

The statistics come from health boards and show that since 2010 there have been 1,424 cases of people treated in hospital after using the substances.

The highest numbers were in NHS Ayrshire and Arran where there were 450 admissions over the four years, including 92 last year, and the NHS Fife area, where there were 449 admissions, including 118 last year.

The lowest was in NHS Shetland where there was just one admission last year, bringing the total there to six over the four year period.

But some health boards, including NHS Greater Glasgow and Clyde and NHS Lothian, said they did not hold the information, meaning that the real total could be much higher.

Scottish Conservative health spokesman Jackson Carlaw, who obtained the figures, said that the NHS was seeing a new set of challenges posed not only legal highs, but by drugs used to enhance image and performance.

"The numbers involved are just the tip of the iceberg, there's clearly a much larger problem bubbling away underneath," he said.

"We can't afford to be blindsided by this because so much of our attention is dominated by what we would regard as traditional problem drug users."

The Tory MSP added: "It's important that both performance and image-enhancing drugs and legal highs form a key part of any future drugs strategy in Scotland.

"As a snapshot, this is extremely concerning and I hope we can take action to see these numbers drop in future years."

A Scottish Government spokesman conceded that the use of performance and image-enhancing drugs was a "concern" and added that while ministers were keen for proper regulations to be brought in, the matter is reserved to Westminster.

He said: "The growing use of performance and image-enhancing drugs is of concern.

"This is a matter that is reserved to Westminster and we are keen to see proper regulations of these substances.

"We have made a record investment of over £224 million in frontline drug treatment and support services, with £30.4 million of this provided for frontline drug treatment services and support in 2014-15 alone, ensuring that people have credible and accessible advice on drugs to help them make the right health choices.

"If anyone does experience adverse effects they should seek medical help immediately or discuss the use of such substances with a medical professional before using."