It comes after a small-scale survey showed most respondents waited more than five years before accessing support.
Justina Murray, CEO of Scottish Families Affected by Alcohol and Drugs (SFAD), said the findings were in keeping with her knowledge of family members’ experiences, and added that the delays “cannot continue”.
She called for more funding for support services, and more promotion of them, as in some cases family members may delay seeking support as they do not know about it or do not believe they are eligible.
Mark Kennedy, CEO of Circle, which supports families and children affected by issues including substance use, said there is a “lack of awareness” about services.
Ms Murray said: “In recent years we have heard repeated calls for better funding for treatment, care and support for people using alcohol and drugs, and we support such additional investment. However this must be matched by equitable funding for the families harmed by such substance use.”
“There are good examples of high quality family support in Scotland but, as families have told us directly, there is nowhere near enough of it to go around to meet the need.
"We are calling for significant, sustained and strategic investment in high quality family support for children, young people and adult family members harmed by Scotland’s longstanding relationship with alcohol and drugs. This must reach right across the country so all families can get the support they need as soon as they need it.”
She added that more families need to be reached by this support.
“We know that by the time families come to us, they're often in a state of crisis, things have got to breaking point… often there’s not a lot of support early on, which of course means that things are a lot worse than they would have been if we had reached families sooner,” she said.
Mr Kennedy called the Scottish Government whole family approach a “really positive step forward”, but said there is still more work to be done.
He said: “With a lot of families, it takes them a while to come to terms with the fact that they need support, and then there's a lot of shame and stigma around, drug use within families, that acts against them coming forward and asking for support… if support was more available and there was more information available for people more widely then people would probably access that support at an earlier stage.”
Minister for Drugs Policy Angela Constance said: “We know there are not simple or quick solutions to the complex and longstanding issues related to substance misuse, but we’ve committed additional investment of £250 million over the next five years.
“It’s vital that children, young people and families are supported in their own right when they are impacted by the drug or alcohol use of a loved one and I am grateful to SFAD for this work with children, young people and adult family members, and we will incorporate the findings into our plans to improve holistic family support due in the summer.”