The U.S. Food and Drug Administration announced that three unnamed Japanese companies recalled the active ingredient in heparin manufactured by Scientific Protein Laboratories, based in Wisconsin.

At least four people have died of allergic reactions to the drug and hundreds have suffered life-threatening reactions in the United States and Germany, though none of these reactions stemmed from products manufactured at Scientific Protein, the Chicago Tribune reported Tuesday.

"The three Japanese companies made clear that the recall was simply a precaution, as there has not been a pattern of adverse reactions to heparin reported in Japan similar to what has been observed in the U.S. and Germany," Scientific Protein said in a statement Monday.

FDA officials said it found "heparin-like" substances in recalled batches of heparin sold by Baxter International Inc. (NYSE:BAX) linked to production facilities in rural China.

The supply chain for heparin production begins in unregulated family-owned pig farms in rural China before reaching Scientific Protein's Chinese facilities.