The German DAX index provisionally ended more than 3 percent lower, in its biggest one-day percentage drop since March 2014, according to Reuters. .
This followed a rally in the euro-dollar to $1.11, after weaker than forecast U.S. first quarter economic data. This came in at an annualized 0.2 percent versus estimates of 1.0 percent.
The Dow Jones Industrial Average briefly fell 150 points after the data, before recovering somewhat.
In Europe, exporting firms such as pharmaceuticals and autos were hit hard by the rally in the euro, with Merck falling close to 5 percent and Bayer and automaker Volkswagen both off over 3 percent.
A failed bond auction in Germany also weighed on sentiment, with yields surging on fixed income assets.
Read MoreGerman yields spike; shrug off negative yield fears
Plus, an euro zone economic, business and industrial sentiment index showed a fall to 103.7 in April from 103.9 in March on Wednesday morning, according to the European Commission.