Health chiefs say they are pulling out all the stops to meet waiting time targets.
But they warned it could take up to six months before there is an improvement.
Figures released last month show that more people here were waiting longer for treatment to begin than in any other part of the country.
And it appears that the situation is continuing to deteriorate.
It comes at a time when health authorities across Scotland are facing severe pressure to cope, in particular in Accident and Emergency departments which have faced large numbers of additional patients due to winter ailments and GP surgeries being closed over the festive period.
Although NHS Forth Valley should have been meeting the Scottish Government target of treating 90 per cent of patients within 18 weeks, in December The Falkirk Herald revealed it failed to do so for four months in succession.
With the last published figures showing an 83.7 per cent compliance rate for October, a health board spokeswoman admitted that hitting the targets had been “challenging”.
Although it is currently finalising figures for the last quarter of 2012, which are due to be published in February, it is understood that in November the rate had fallen to 81.9 per cent.
This week, the health authority outlined steps it is taking to remedy the situation.
A spokeswoman for NHS Forth Valley said: “We are continuing to work towards meeting the 18 week target and, over the last few months, we have taken a number of actions to help improve our performance in this area.
“This has included recruiting additional specialist staff, organising additional clinics and increasing theatre time for a number of specialities where we have seen a significant increase in demand. These include audiology, neurology and ophthalmology.”
But she warned it would be some time before these measures started to impact on the target.
She added: “We expect to see improvements in our performance over the next six months.”
The spokeswoman said the NHS across Scotland had faced “significant challenges” in recent weeks to cope with numbers turning up at A&E.
She added: “In Forth Valley, as part of our winter planning arrangements, we have increased staffing levels in our Emergency Department and opened additional beds within Forth Valley Royal Hospital to help meet demand and reduce waiting times.
“As a result, while a number of non-urgent patients have had to wait more than four hours, no patient waited more than 12 hours in our Emergency Department over the last four weeks.”
On Wednesday, a spokeswoman for the Scottish Government said: “We are continuing to work closely with those health boards who are not meeting the target to address any issues and to ensure future compliance.
“In addition, we have provided an extra £3 million to help boards manage winter pressures to make sure that people do not have to wait longer than necessary to be treated.”