The Food and Drug Administration says medications used to treat acid reflux and other conditions do not cause stomach impurities.
Zantac OTC and similar medications were pulled from shelves in September.
That followed an FDA statement saying the drug contained low levels of NDMA, a substance classified as a probable human carcinogen.
The FDA said on Friday, however, that its testing revealed the medication does not form the impurity in the digestive system after all.
They added that the amount of NDMA is similar to those in grilled or smoked meats.
Although FDA testing showed much lower levels than some scientists first claimed and some levels still exceed what the FDA considers acceptable for these medications.
The FDA said companies will be asked to voluntarily recall their products if they contain levels above the limit.