Governments have a few tools they can use to stem the outflow of capital. One of them is to sharply raise interest rates. Those higher rates translate into potentially stronger returns for investors. As such, they can attract money into an economy, which helps prop up a currency.

But it’s a tricky play to pull off.

Brazil raised interest rates sharply to stop an outflow of capital in the late 1990s, ultimately pushing benchmark interest rates to roughly 40 percent. More recently, in 2014, Turkey suddenly ratcheted up a key central bank rate to 10 percent from 4.5 percent in order to stop a sell-off in the lira.

That same year, the central bank of Russia pushed interest rates sharply higher — to 17 percent from 10.5 percent — to keep the ruble from collapsing in response to sanctions over the annexation of Crimea and a sharp drop in oil prices. Russia also has one of the biggest interest-rate jumps on record, when in 1998 its rates reached 150 percent in an effort to stem another impending collapse of the ruble.

But high interest rates have economic costs. They make it particularly difficult for businesses and consumer to borrow money. The lack of spending, in turn, can slow growth and ultimately spark a recession.

The key for Argentina will be to keep rates high just long enough to inspire confidence that policymakers have halted the currency run, but not so long that the increase drains the economy.

“This was done in order to stop the bleeding,” Mr. Gersztein of BNP Paribas said. “It’s like you have someone in the E.R. You need to take very short-term, bold decisions.

“Then once you stabilize the patient,” he added, “you need to take different decisions in order to make the patient get better and recover.”