Almost a quarter of patients with a mental health problem are waiting more than three months to see an NHS specialist, leading psychiatrists have warned.
The Royal College of Psychiatrists said that long waits for mental health care "have been deemed acceptable".
The College's poll of 500 mental health patients found that 24% waited more than three months to see an NHS mental health specialist.
And more than one in 20 (6%) said they had waited for more than a year.
One patient told the college they had waited more than 13 years to get the right support.
Long waiting times led to significant personal problems - with around one in three of those surveyed saying that their wait contributed to relationship problems, including divorce (36%), financial troubles (32%) and work problems (34%).
The Royal College of Psychiatrists warned that long waits for NHS mental health treatment are largely down to gaps in the mental health workforce, particularly psychiatrists.
It has launched a new campaign urging medical students to become doctors who specialise in mental health.
It said over the last five years, the number of consultant psychiatrists has increased by just 3.3% in the NHS in England, while the number of consultants across the rest of the health service increased by 21%.
Professor Wendy Burn, president of the Royal College of Psychiatrists, said: "It is a scandal that patients are waiting so long for treatment.
"If they were waiting many months or even years for cancer treatment there would be an outcry, but for some reason when it comes to mental illness long waits have been deemed acceptable.
"Fortunately, the tide is turning with a 2% rise in the number of psychiatrists in the NHS in England in the past year and the number of trainees in psychiatry in Great Britain up by a quarter between August 2017 and August this year.
"But as our research shows, the failure to give people with mental illnesses - from depression and anxiety to bipolar disorder and PTSD - the prompt help they need is ruining their lives: preventing them from doing their jobs effectively, maintaining key relationships like their marriage and keeping their heads above water financially."
Responding to the poll, an NHS England spokeswoman said: "Any campaign that looks to boost workforce numbers is welcome but is more likely to succeed if it also reflects the good work happening on the ground and the positive reasons that make mental health such a rewarding career.
"It would be appropriate to highlight that - after decades of underinvestment - the NHS is ramping up mental health services including expanding talking therapies and improving treatment times while the NHS' long-term plan will set out further priorities for the years ahead."
The survey comes as experts from around the world prepare to gather in London for the first annual Global Ministerial Mental Health summit.
The summit, co-hosted by the UK Government and the OECD, will see experts from around the world gather to discuss how to improve outcomes from the one in four people who suffer a mental health problem at some point in their lives.
The Duke and Duchess of Cambridge are expected to attend along with delegates from more than 50 countries.
At the summit, Health and Social Care Secretary Matt Hancock will launch the UK Government's ambition to achieve parity between mental and physical health across the globe.
Mr Hancock said: "The world must unite and take this opportunity to deliver parity for mental health so it is treated the same as physical health.
"Countries from across the world are in London to agree action to tackle one of the defining challenges of the 21st century.
"Whether it's challenging discrimination, promoting wellbeing at work, adopting new technologies, or empowering young people to take steps to a healthier future, long-lasting commitments will be made at this summit which will be a step towards achieving better mental health care for all."
Meanwhile, a separate small poll of GPs found that 80% said that finding a treatment that works for mental health patients is trial and error.
And 68% believe the effectiveness of mental health treatments varies between patients, according to the survey of 100 British family doctors.
The poll, conducted by mental health research charity MQ, also found that six in 10 feel equipped to provide personalised treatments for patients with mental health problems.
"Without a solid foundation of research, GPs are using a currently limited understanding of diagnosis and treatments," said Lindsey Bennister, chief executive at MQ.
"This often means individuals are recommended support which often ends up being on a trial and error basis."
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