The rate of inflation climbed to a three-year peak of 4.2% in May and quashed any chance of the Federal Reserve cutting interest rates this summer, but the last snapshot of consumer prices also appeared to show limited damage so far from higher oil costs.
The consumer price index rose 0.5% last month following a similarly sharp increase in April.
The yearly rate of inflation moved up to 4.2% from 3.8% in April, touching the highest level since the middle of 2023.
In a more reassuring sign, the so-called core price index increased a smaller-than-expected 0.2% in May, a tick below the Wall Street forecast.
The 12-month increase in the core rate advanced to 2.9% from 2.8%.
While the headline increase in inflation in May was disappointing, the smaller increase in the core rate suggested the damage from higher oil prices so far has been limited.
Oil prices soared after the U.S. attack on Iran at the end of February, but they have fallen from recent highs to give Americans some relief.
Still, inflation is far from the Fed's 2% goal and heading in the wrong direction.
New Fed Chair Kevin Warsh won't be able to cut interest rates anytime soon, as President Trump had hoped when he announced Warsh as the new chief earlier this year.
Warsh will preside over his first Fed meeting next week.