Ultra-loose monetary policies prescribed by some developed countries for their economic woes can only provide a short-term relief rather than a cure for subdued economic growth, and an "overdose" of easing measures could lead to policy dilemmas.

Federal Reserve Chairman Ben Bernanke said Tuesday in his biannual testimony before Congress that the U.S. economic growth decelerated and the bank is prepared to take further action to promote a stronger economic recovery.

However the Fed chief gave no explicit clues on whether to adopt another round of easing measures, which disappointed the market a lot as investors had been watching closely and waiting with high expectations for the minutes of the Federal Open Market Committee's June meeting.

The testimony and the federal funds rate that has been left within the record-low range of zero to 0.25 percent since December 2008 provide strong evidence that the United States is caught in a "liquidity trap" and leaves itself little room for further easing measures.

Since the onset of the financial crisis, the Fed has been committed to ultra-loose monetary measures to boost the economy which only turned out to be ineffective.

The Fed completed two rounds of quantitative easing programs, know as QE1 and QE2 in 2008 and 2010 respectively. And on June 20, it decided to prolong the Operation Twist program till the end of this year as an alternative to the QE3.

However, the U.S. unemployment rate was still kept on a record-high of 8.2 percent in June, and consumers remained reluctant to open their wallets, leading to consecutive drops of retail sales over the past three months.

Moreover, large-cap companies' second-quarter poor earnings figures released over the past couple of weeks further suggested that the Fed's easing measures are not a proper remedy for the country's economy.

The Fed's ultra-loose monetary policy, which is seen to be driven by the fluctuation of economic data rather than economic rules, has attracted sharp criticism both at home and abroad.

The country's sluggish growth and stubbornly high unemployment rate were not caused by, nor could it be cured by, monetary policy, said Allan H. Meltzer, professor of political economy at Carnegie Mellon University in an article on The Wall Street Journal.

"Executing monetary-policy changes in response to transitory data is a mistake... Rule-based monetary policy brought us a far better economic outcome than discretionary ups and downs," he said.

The policies that are really needed are on the fiscal side, Meltzer said. "Instead of more short-term stimulus, we need a government that puts us on a path toward a balanced budget over time, mainly by reducing spending."

Therefore, the Fed should stop blindly taking another dose of painkiller for a short-term boost and should be cautious of the side effects of relying too much on ultra-loose monetary policies.

Ultra-loose monetary policies are like the Pandora's box that once opened, may create unimaginable detrimental effects to the U.S. and the world economy at large, which cannot be undone easily.

John Taylor, a renowned professor at Stanford University, held that the Fed's ultra-loose monetary policy has led to economic unpredictability and the large expansion of bank money has created inflationary risks for the future.

Besides, the Fed's abuse of the "aspirin" of liquidity is also irresponsible for other economies that are striving to tap new trade and growth potentials and to create jobs.

Given the renewed intensification of the eurozone crisis and U.S. fiscal uncertainty, which were underscored by Bernanke as two main sources of risks to the U.S. economic recovery, Congress should address the nation's fiscal challenges in a way that takes into account both the need for long-term sustainability and the fragility of the economic recovery.

How to best use monetary policies to stimulate the economy is a crucial test to Bernanke's wisdom. More importantly, it is of great importance to a sound recovery of the world's largest economy.