The Food and Drug Administration has started releasing safety reviews for recently approved drugs, in order to inform doctors and consumers about side effects that have gone undetected or unreported.

U.S. health officials will base their reviews on reports submitted by consumers, doctors and companies, as well as medical literature and ongoing studies. The FDA said some side effects do not become apparent until after a drug gains approval since medications are often only tested on a small segment of the population.

The agency has posted reviews for 24 medicines and two vaccines so far.

In a few cases, the evaluations are troubling. For stomach, bladder and kidney antibiotic Doribax, for example, the FDA reports serious liver damage, troubles with blood clotting and seizures, but said that it would not require any new labeling changes at this point.

FDA official Dr. Robert Boucher told Reuters that the reports show “for the most part, we know a lot from [pre-market] clinical development.”

A 2007 law requires the FDA to prepare a safety summary for prescription drugs 18 months after approval or after 10,000 people have used them, whichever comes later. Some drug reviews will also be retroactive, with the oldest dating back to September 2007. It will release its information quarterly.