The rand was off its lows against the dollar in noon trade on Thursday in what a trader described as an "erratic" market.
The local currency hit 8.30 overnight as the weakening global economy curbed risk appetite and as the Fed's message disappointed.
"The rand can weaken even further than it did overnight as the euro is looking softer," a local currency trader said.
"What's happening now is all connected to the flight from risk - in fact emerging markets' currencies across the board are getting hammered - it isn't only the rand."
While the SA Reserve Bank MPC's decision on rates was awaited, no change was expected, the trader added.
At 11:42 local time, the rand was bid at 8.1790 to the dollar from its previous close of 8.2384. It was bid at 11.0186 to the euro from 11.1872 before, and at 12.6230 against sterling from 12.7661 previously.
The euro was at US$1.3476 from US$1.3582 before.
RMB analysts said in a note that on Wednesday, the rand had posted its largest daily loss since the onset of the global financial crisis in 2008, weakening by almost 8.5%.
"Implied volatility levels on dollar rand options have surged to levels last seen in 2009, while risk reversals suggest a strong possibility of further weakness."
RMB said it had warned of a potential break of 8.00 earlier in the week, citing the possibility of a systemic event in Europe as a possible trigger point.
"Although liquidity pressures have eased, we are still unsettled by the volatility in European financial markets."
IMF estimates of mammoth reductions to EU bank holdings and its adverse impact on the real economy in Europe were additional cause for concern.
"Though the analysis, contained in the latest global financial stability report relates to the impact of peripheral debt turmoil on European markets, it magnifies global banking sector risk."
RMB added that while the Fed's outlook on the US economy had not changed drastically since August, its fresh attempt to stave off a recession through additional bond purchases, highlighted its anxiety over the sluggish growth and a broadening of eurozone debt woes to US shores.
Fed Chairman Bernanke echoed this point, alluding to "significant downside risks to the economic outlook".
"Operation Twist will not inflate the size of the Fed's balance sheet and might prove more effective in reducing long-term interest rates by 'twisting' the shape of the yield curve.
"Its impact on the broader economy, however, is questionable especially since the cost of borrowing is not the problem. A lack of business confidence and the inability of mortgage borrowers to refinance at lower rates continue to stoke market anxiety."
Despite the negative implications of Operation Twist for the US dollar, the currency was likely to strengthen by default, RMB said.
"With whispers of a lower EUR/CHF ceiling, that was imposed by the SNB earlier this month, safe haven flows will revert to the US and Japan.
RMB added that international event risk would continue to steer the market.
"Angst could entrench the dollar/rand above 8.00 for the remainder of the week, amplifying upside risks to the rand crosses."
Meanwhile Dow Jones Newswires reported that in currency markets, the euro was lower after the dollar gained following the Fed's announcement.
Investors expressed disappointment with the Fed's downbeat assessment of the US economy and its latest attempt to boost it.
Traders said the Fed's new effort, known as Operation Twist, was "underwhelming" and raised questions about how effective the measure could be.
"The market expects more from the Fed than a change in balance sheet. Many were hoping for QE3, but have been left disappointed," said a trader.
