Sexually abused children must often be suicidal, self-harming or developing serious problems to receive therapy, the NSPCC has warned as it revealed that nearly all health professionals believe the mental health care for them is inadequate.
A total of 96% of the 1,256 psychologists, GPs, teachers and social workers surveyed by the charity said it was insufficient and 78% said they felt access to services had worsened in the last five years.
Many children have to wait more than five months before they receive specialist support and some professionals surveyed said that the NHS did not see help for child abuse victims was as a priority.
"All too often therapeutic services are only offered to children after abuse if they're suicidal, self-harming or developing chronic mental health problems," the NSPCC said.
Zoe (not her real name) said:“My carers took me to the doctors two months after I went into care and I told them that I was self-harming and that I felt like killing myself but I didn’t get a mental health assessment. They didn’t prescribe me anything or offer me counselling, they just told me that I would get through it. I felt like she didn’t care or understand.”
One senior clinician told the BBC that staff felt "desperate" about the lack of support.
One paediatrician said the situation was "very bad", adding the Child And Adolescent Mental Health Services (CAMHS) was "not interested and there is no suitable alternative.”
A GP told the NSPCC: “More referrals are being rejected even though it seems clear there are real problems. Therapy is time-limited and there seems to be less access to people with specialist knowledge.”
NSPCC chief executive Peter Wanless said the state of care "shames the nation". "The views of professionals in this survey speak loud and clear," he said.
"The government and those that commission services urgently need to increase what is currently available to support this most vulnerable group of children."
Dr Jon Goldin, from the Royal College of Psychiatrists, told The Today Programme the issue was "a serious problem".
"A very high percentage of children who suffered sexual abuse do end up with long-term mental health problems," he said
"Thousands of abused children don't get the kind of early therapy they need. It's hard to know exactly the figures... There are increased numbers of children being abused in our society today... The numbers are very large and the children are not getting the help they need."
Interviewer John Humphrys asked: "This is a question not an assertion, can it be the case that it's better for [abuse victims] to bury the memory? Is it ever better to bury the memory?"
Dr Goldin said that was "not a concept clinicians would agree with".
He added: "It's very important that children have the opportunity to have a therapeutic relationship, to build up a relationship of trust and security with a professional who can help them work through the trauma.
He said a failure to treat the mental impact of abuse could lead to "children becoming depressed, self-harm, PTSD, a significant impact on their daily functioning".
He added: "As these children grow up and become parents themselves, the cycle of deprivation, abuse and difficulties can be perpetuated, so it's crucial to intervene young to help these children get the help they need in order their longer-term problems can be prevented."
More than half of respondents said that tight criteria to access NHS mental health services means these children are increasingly struggling to access vital help.
The survey coincides with launch of the NSPCC's It's Time campaign, in which it is pushing for increased funding for support services, clear government guidelines on when a child should be offered therapeutic support and more research into the scale of the problem.
A Department for Health spokeswoman said: "We are investing £1.4bn into young people's mental health and are working with local areas to improve services in hospitals, schools and communities so young people get better quality mental health care as quickly as possible, a key part of which involves helping the victims of abuse."