While these issues are rarely serious enough to get the drug pulled from the marketplace, researchers say new drugs should be monitored for years after they are released to the public.
Cutting-edge therapies known as biologics, psychiatric drugs, and medicines that were fast-tracked by the US Food and Drug Administration were most likely to require additional safety warnings after approval, said the report in Journal of the American Medical Association (JAMA).
For the study, Yale University researchers analyzed 222 new drugs approved between 2001 and 2010, and followed up on them through 2017.
A total of 32 percent of new drugs (71 in all) were flagged for a safety issue after approval, the study said.
Three drugs were withdrawn because of health risks: Valdecoxib, an anti-inflammatory; Tegaserod, a drug used for the treatment of irritable bowel syndrome; and Efalizumab, a drug used to treat psoriasis.
There is "very rarely a drug withdrawal, but more commonly a black box warning, or drug safety communication issued by the FDA to let physicians and patients know that new safety information has been determined," said Joseph Ross, associate professor of medicine and public health at Yale.
Most clinical trials that are done on a drugs before they are approved involve fewer than 1,000 patients studied over a period of six months or less.
The findings show "there is the potential for compromising patient safety when drug evaluation is persistently sped up," said Ross, urging regulators to regularly monitor new drugs for signs of safety concerns.