A major survey by the NSPCC found that nine out of every 10 professionals surveyed felt services to help abused children overcome their trauma are not good enough.
More than three quarters said it has got more difficult in the last five years to access therapy.
Nearly all of those surveyed (96 per cent) said there are not enough child and adolescent mental health services (CAMHS) for children who have been abused and 98 per cent said provision of other therapeutic services is insufficient in their area.
Meanwhile, more than 50 per cent of professionals said criteria is too stringent for abused children to access NHS support.
The survey, which involved 1,000 professionals – including psychologists, GPs, teachers and social workers – found that longer waiting lists, reductions in spending and higher thresholds for therapy were making it harder for affected children to access vital therapeutic services.
The NSPCC has launched a campaign, It's Time, to raise awareness of the barriers abused children face getting help, and to call for improved access to therapeutic services.
NSPCC chief executive Peter Wanless said children are often left alone to deal with the emotional and psychological consequences of abuse and all too often face long waits for help with their trauma, or the services offered aren’t appropriate.
He said that although a government pledge to invest in children's mental health services up to 2020 was welcome, more needs to be done.
“The views of professionals in this survey speak loud and clear," he added.
"The government and those that commission services urgently need to increase what is currently available to support this most vulnerable group of children. Getting help to these children earlier is vital and can prevent longer term damage to the lives of those who have survived the horror of abuse.”
Children’s commissioner for England Anne Longfield said: “Children that have experienced trauma will often have physical and emotional scars that remain with them for life, so it is vital that children who are abused get the support they need to help them to recover.
"Our own report on abuse in families, published late last year, recommended that children receive a holistic package of support, tailored to their needs, including therapeutic help from the moment it is known that they have been abused.
“NSPCC’s important report confirms that support for children who have been abused is seriously lacking and that much greater help is needed.”
Max Davie, member of the Royal College of Paediatrics and Child Health, said that without the right support, an abused child may have to have to live with devastating problems caused by their abuser as they move through childhood and into adulthood.
"That’s why it’s important any child who has been abused has access to therapeutic services at the right time and in the right place," he added.
“For too long policymakers have failed to tackle the crisis in child and adolescent mental health so much so that it is now becoming a hidden epidemic. And the figures highlighted in today’s report reflect this.
“While we welcome the recent funding increases for CAMHS, we are concerned that too much has been focused on simple treatment of clear mental health symptoms. These children often present in complex, aggressive and self-destructive ways, and only a comprehensive, integrated CAMHS system will be able to serve their needs adequately."