Methadone must not be the only treatment available to drug users, the Legal Affairs Minister has said.
An independent expert group has been commissioned by Roseanna Cunningham to gather evidence on the effectiveness of treating users with methadone and other replacements.
The number of people on methadone has risen by a tenth in the last five years, from 22,224 in 2007 to 24,507 this year.
Chief Medical Officer Harry Burns will lead the expert group in collaboration with the independent Drugs Strategy Delivery Commission.
Chaired by Dr Brian Kidd, from the delivery commission, the new group will examine the evidence that medical professionals use to justify prescribing methadone.
Dr Burns said opiate-replacement therapy is "an important and complex issue".
He said: "We know that opiate replacement therapies stabilise the lives of people seeking to address their drug addictions. This group brings together great expertise and its work will give us a clearer picture of how these therapies are being used across Scotland."
The panel will make recommendations to the Scottish Government, for consideration in Parliament.
Ms Cunningham said: "Prescribed drug treatment has saved many thousands of lives in Scotland. It is the responsibility of the professionals to determine the most appropriate treatment for each person seeking medical help with addiction problems.
"However, the Scottish Government is clear that prescribed drug treatment is not, and cannot be, the only treatment option available on the pathway to recovery. People have a right to a full range of treatment and support options and, to decide in consultation with professionals, what is best for them.
"We know that between April 2011 and March 2012, prescribed drug treatment, including but not exclusively methadone, was less than one-fifth of treatment options started.
"We want to ensure our services in Scotland are as effective as we can make them. This group's work will enhance the quality of treatment and long-term recovery outcomes in Scotland by gathering robust evidence and providing effective and constructive challenge to what we already know.
"The road to recovery is absolutely the right approach for dealing with Scotland's long legacy of drug misuse. I am delighted to call upon the expertise of this group, led by the Chief Medical Officer, to strengthen the evidence base, and look forward to receiving their findings."
Scottish Conservative health spokesman Jackson Carlaw said: "The methadone programme in Scotland has been an utter disaster and now costs more lives than the drug it was supposed to help people off. A review of its use is long overdue but the important thing is getting people to stop taking heroin, not simply find a stop-gap.
"I hope as a result of this a more driven focus on abstinence-based treatment is considered, and it is important we don't come out the other end with even more replacement therapies which often don't help anyone, and cost the public purse millions."