WASHINGTON — Inflation is not going anywhere in the United States.

U.S. consumer prices were unchanged in July from June, as a small drop in energy costs offset slightly higher food prices. The consumer price index hasn’t changed since March, evidence that the weak economy is keeping inflation in check.

Core consumer prices, which exclude food and energy costs, ticked up 0.1 percent last month, the Labor Department said today. More expensive medical costs, clothing and rents pushed up core prices.

Prices increased 1.4 percent in the 12 months ending in July. That’s down from 1.7 percent in June and is the smallest yearly increase in 20 months.

Core prices have increased 2.1 percent in the past year, down from a 2.2 percent pace in June.