More than half a million bottles of blood pressure medicine have been recalled after U.S. health officials found traces of a potentially cancer-causing chemical. The U.S. Food and Drug Administration (FDA) announced that Teva Pharmaceuticals USA has voluntarily recalled certain batches of prazosin hydrochloride capsules, a medication commonly prescribed for high blood pressure.

The recall, issued on October 7, affects about 580,000 bottles of the drug, including 1 mg, 2 mg, and 5 mg capsules. According to the FDA, these products may contain a chemical impurity called N-nitroso Prazosin impurity C, which belongs to a group of substances known as nitrosamines. Long-term exposure to these impurities has been linked to an increased risk of cancer.

Prazosin is an FDA-approved drug that helps relax blood vessels, allowing blood to flow more easily and lowering blood pressure. It’s also sometimes prescribed for PTSD patients to reduce nightmares and improve sleep. While the FDA classified this recall as a Class II risk—meaning the chances of serious health issues are relatively low—it’s still important for patients to take it seriously.

If you use prazosin, you should check the lot number on your medication bottle and contact your pharmacist or doctor to confirm whether it’s part of the recall. You should not continue using the affected medication. Instead, safely discard it and ask your healthcare provider for a replacement.

Teva Pharmaceuticals, based in Parsippany, New Jersey, has not yet provided detailed guidance for consumers but is cooperating fully with the FDA to remove the affected lots from circulation.