The third straight month of strong increases in the Consumer Price Index reported by the Labor Department on Wednesday underscored the mounting pressure on households, who are increasingly tapping their savings to fund spending.
Inflation eroded wages for a second consecutive month in May, which could weigh on overall economic growth.
The soaring cost of living is a political liability for US President Donald Trump and his Republican Party, seeking to retain control of Congress in the midterm elections in November.
Trump won the 2024 presidential election in large part because of his promise to lower inflation, but has seen his approval rating tumble as frustration mounts over his handling of the economy.
"Americans are getting squeezed financially by inflation," said Heather Long, chief economist at Navy Federal Credit Union.
"It's not just bad vibes about the economy now, there are real financial pressures, especially on middle-class and lower-income households."
The Consumer Price Index increased 4.2 per cent in the 12 months through May, the largest gain since April 2023, the Labor Department's Bureau of Labor Statistics said.
The CPI advanced 3.8 per cent year-on-year in April and rose 3.3 per cent in March.
Prices increased 0.5 per cent over the month after climbing 0.6 per cent in April.
The rise in inflation was in line with economists' expectations.
The US central bank tracks the Personal Consumption Expenditures Price Indexes for its 2.0 per cent inflation target.
All inflation measures are running well above the Fed's target.
Real average hourly earnings dropped 0.7 per cent in the 12 months through May after falling 0.3 per cent in April.
A 3.9 per cent jump in the price of energy goods accounted for more than 60 per cent of the rise in the monthly CPI.
Energy prices rose 3.8 per cent in April.
They vaulted 23.5 per cent in the 12 months through May.
Petrol prices accelerated 7.0 per cent over the month and were up 40.5 per cent from a year ago.
Prices at the pump have retreated in recent weeks as oil prices eased, raising cautious optimism among economists that May could be the peak in CPI inflation.
Inflation last month was also lifted by higher rents.
While food price growth slowed after accelerating in April, risks remained to the upside as the war, now in its fourth month, has raised the cost of fertilisers.
Grocery prices edged up 0.1 per cent, with increases in the prices of non-alcoholic beverages, cereals and bakery products as well as fruits and vegetables partially offset by decreases in the cost of meat and dairy products.
