Every day thousands of Americans rely on the blood thinner Heparin to survive.

Now that drug is under suspicion for 21 deaths and hundreds of allergic reactions. Baxter International, a major manufacturer of the drug, has stopped selling almost all forms of Heparin.

CBS News medical correspondent Dr. Emily Senay reports that officials say they have not yet identified the cause, but are looking to China where nearly half of Heparin’s raw ingredients come from.

Until last week, leading manufacturer Changzhou Scientific Protein Laboratories had no operating license and had been completely unregulated, either by Chinese authorities or the Food and Drug Administration, a violation the FDA’s own inspection policy.

The FDA finally inspected the plant two weeks ago.

FDA Commissioner Andrew von Eschenbach says that the investigation of the Heparin issue is “active and underway.”

The inspection revealed “use of materials from an unacceptable vendor'” and a failure to “identify impurities and deficiencies'” with manufacturing equipment.

(Source: CBS2)