Even those with good credit ratings are not excepted. American Express, which traditionally catered to more upscale cardholders, said it would be increasing effective interest rates by 2 or 3 percentage points for some of its credit card holders — a move that could, for example, push a 15 percent rate up to 18 percent.

“We think it’s prudent given the nature of those products and the economic environment we face,” Daniel Henry, its chief financial officer, said in a recent conference call.