The 2008 heparin contamination

Between Nov. 19, 2007, and Jan. 31, 2008, 113 patients in 13 states had 152 allergic-type reactions after receiving heparin, in an outbreak first detected at a hemodialysis facility. The reactions often meant a sudden drop in blood pressure, nausea and shortness of breath within 30 minutes of the dose, according to the CDC-led investigation published in the New England Journal of Medicine².

When investigators tested unopened vials from the facilities that reported reactions, they found oversulfated chondroitin sulfate, or OSCS, a chemically modified substance that mimics heparin closely enough to slip past the standard quality tests of the time.

Heparin is an old, inexpensive blood thinner used in dialysis, surgery and hospital care. FDA later described the 2008 contamination as an apparent case of deliberate, profit-driven adulteration, and it changed how regulators and drugmakers police the raw materials behind finished medicines. Most of the timeline below comes from the 2010 Government Accountability Office review¹ of FDA's response.

How the contaminant was found

FDA's investigation began on Jan. 7 to 9, 2008, GAO found¹. The first recall, covering nine lots, came on Jan. 17. FDA formed a Heparin Task Force on Feb. 22, and a much broader recall of one manufacturer's vials followed on Feb. 29, once the agency had confirmed that pulling the product would not cause a shortage.

Identifying the contaminant took longer. On March 5, FDA identified the type of contaminant in suspect lots, and on March 6 it posted screening methods to its website so manufacturers could check their own stock. On March 17, it named OSCS. A structural analysis in Nature Biotechnology⁴ described a disaccharide with an unusual sulfation pattern and noted that “traditional screening tests cannot differentiate between affected and unaffected lots.”

A companion NEJM study³ supplied the biology. OSCS from contaminated lots, and a synthetic version made as a reference standard, activated the kinin-kallikrein pathway in human plasma, which can generate bradykinin, a potent dilator of blood vessels. It also produced two inflammatory complement fragments, C3a and C5a. Given to pigs by infusion, OSCS-containing heparin caused low blood pressure, the same sign seen in patients.

Linking the reactions to the product

CDC investigators compared 21 dialysis facilities that reported reactions with 23 that did not. The case-control analysis² found that heparin from one manufacturer was present in every case facility and in 4.3 percent of control facilities. Of 130 reactions for which lot information existed, 128 (98.5 percent) happened in a facility that had contaminated heparin on site. Of 54 reactions with a known lot number for the dose given, 52 (96.3 percent) followed contaminated heparin.

Deaths are harder to pin down. According to GAO¹, FDA reviewed 701 adverse event reports associated with heparin and analyzed 94 reports of deaths. It judged three of those deaths “probable or likely” linked to heparin. Even so, GAO wrote that “FDA was unable to link any of the adverse events to contaminated heparin,” in part because reports often lacked lot numbers and patients were already seriously ill. Reports fell back to pre-crisis levels by April 2008; 176 drug-related reports had been filed for February 2008, against 13 for February 2007.

Where the heparin came from

Heparin is extracted mainly from pig intestines. GAO¹ described a supply chain in which thousands of small pig farms and village workshops in China process the intestines, with crude heparin consolidators standing between those workshops and the companies that make the active ingredient. China was the primary source of crude heparin for US manufacturers, and “more than half of the finished heparin products in the United States and globally are made from Chinese-sourced materials.” Our explainers on where drug ingredients come from and China's role in drug ingredients cover the broader pattern.

FDA's 2013 guidance on crude heparin⁶ calls the OSCS contamination an apparent example of “economically motivated adulteration,” saying heparin “appeared to be intentionally contaminated with OSCS to reduce the cost of production.” Retrospective testing showed contaminated crude heparin had entered the global supply as early as May 2006, GAO reported¹. The original source was never determined. China denied that the contamination happened there and refused FDA's request for jurisdiction to conduct a criminal investigation. By March 2008, at least 10 countries, the United States among them, had found OSCS in their supply, though only Germany also saw a rise in heparin-associated reactions.

What FDA did, by the numbers

All figures are from GAO-11-95¹. GAO also found that two crude heparin consolidators refused full access during limited inspections and were still classified “no action indicated,” because FDA judged it lacked enough evidence for an import alert. FDA opened offices in China in November 2008. For what inspection findings mean in practice, see our guide to Form 483s and warning letters.

What changed in ingredient oversight

Testing standards changed first. In October 2009, according to GAO¹, the United States Pharmacopeia revised its heparin monograph, the public quality standard every heparin sold in the US must meet, to use nuclear magnetic resonance spectroscopy and chromatography to identify heparin and confirm the absence of OSCS.

FDA then pushed testing upstream. Its June 2013 guidance⁵ asks companies that use crude heparin to test every lot of every shipment for OSCS and for its animal species of origin before use, to know the actual manufacturer of the crude heparin and every repacker and distributor that handled it, and to reject any lot with any amount of OSCS. The guidance notes that one FDA strong-anion-exchange HPLC method can detect OSCS below 0.1 percent. Guidance is not binding, but the same document⁶ says FDA considers OSCS in any form of heparin to render the drug adulterated under the Federal Food, Drug, and Cosmetic Act.

Congress acted in 2012. The Food and Drug Administration Safety and Innovation Act⁷, signed July 9, 2012, expanded FDA's inspection powers over drug plants at home and abroad. Its Title VII includes several provisions that map onto the gaps GAO described:

• Section 705 put registered drug establishments on a risk-based inspection schedule, weighing compliance and recall history, and required an annual public report counting domestic and foreign establishments.
• Section 706 lets FDA demand records in advance of, or in lieu of, an inspection.
• Section 707 makes a drug adulterated if its maker delays, denies or limits an inspection.
• Section 711 states that current good manufacturing practice includes “managing the risk of and establishing the safety of raw materials.”

Those provisions sit behind much of what our pieces on CGMP and onshoring describe. Their roots run back to an earlier integrity crisis, the generic drug scandal of 1989, which produced FDA's debarment powers.

Heparin in FDA's data since then

GxRadar searched FDA's enforcement report records on openFDA⁸ from June 2012 through October 2026 for products whose description includes heparin. There are 119 such records, each covering one product: 97 Class II and 22 Class I. Of these, 94 cite sterility problems, many of them compounded syringes and bags. None mentions chondroitin or OSCS. The full recall history is on our recalls page, and our explainer on how drug recalls work covers the classes.

Supply is a separate issue. In FDA shortage data⁹ through October 2026, heparin sodium injection has been listed since Nov. 14, 2017, and was still marked current in an Oct. 21, 2026, update, with eight presentations listed. It is one of the long-running injectable shortages tracked on our shortage tracker and discussed in why sterile injectables dominate shortage lists.