Spiralling inflation is a "sting in the tail" for Northern Ireland businesses already fighting for survival, a business body has said.
The Office for National Statistics (ONS) said consumer price inflation (CPI) was 5.2% last month, pushed up by rising energy costs.
That was up from 4.5% in August, and leaves inflation more than double the Bank of England's 2% target. It also dwarfs average UK wage growth of just 1.8% a year.
The retail prices index (RPI) measure of inflation, which includes mortgage interest repayments, was 5.6%, up from 5.2% in August.
Wilfred Mitchell, policy chairman at the Federation of Small Businesses (FSB), said high inflation was pushing up operating costs for most businesses, with nearly 60% saying rising energy prices were the most keenly felt of all spiralling costs.
"The rise in inflation will be just another sting in the tail for businesses and follows a raft of bad data over the past week," Mr Mitchell said.
"With the increase in energy bills being attributed to the steep rise, household incomes will be further squeezed which will be further knock to businesses' confidence as people have less money to spend."
David Gibson of Gibson Financial Planning said the rise in inflation was pushing the economy into the "unknown".
"With the economy as febrile as it is, the Bank of England won't dare hike rates to contain rising prices and so we must simply look on, as helpless bystanders.
"The MPC is confident inflation will begin to fall back in the not too distant future, but then the MPC's forecasting is hardly the most reliable."
PwC chief economist Dr Esmond Birnie said households were increasingly "cash-strapped" thanks to rising inflation.
As well as putting pressure on households, retailers were also facing a difficult choice.
He said: "With consumer spending subdued and confidence well into the red zone, retailers may opt for heavy discounting to stimulate High Street sales in the run-up to Christmas.
"And while this may stimulate some retail activity, other factors are at play. The weakness of sterling makes imports more expensive, while oil prices are creeping up, just as the weather forecasters are warning of falling temperatures.
"Collectively this may mean that the Bank of England's forecast that inflation will fall rapidly to 2% may remain challenging, particularly as PwC and others have continued to warn that economic growth is marginal and recovery remains tantalising elusive."
Northern Bank chief economist Angela McGowan said the figures confirmed what households felt already.
"Consumers did not need to see the latest data to confirm that their standard of living has dropped. Households have been enduring continually rising prices for some time now."
She also forecast toughening times for retailers who would probably face "one of the toughest years for the high street in the run up to the Christmas period".
Ulster Bank chief economist Richard Ramsey said the rising inflation highlighted a parallel between conditions in autumn 2011 and those three years earlier.
The jump to 5.2% in CPI was "well above" the level anticipated in the City.
"Only five out of 35 economists surveyed within a Bloomberg survey expected a reading above 5%," he said. "Last month's inflation figures equalled the record high posted in September 2008."
October's figure is likely to be just as high but economists and the Bank agree that the rate will start to fall back next year as January's VAT hike to 20% falls out of the annual comparison.