An international group of scientists is warning pregnant people about the over-the-counter painkiller acetaminophen. In a consensus statement released this week, they argue that enough evidence has emerged to suggest that acetaminophen could be more harmful to take while pregnant than currently thought. They’re now recommending that pregnant people take it as little as medically needed until health regulators can reexamine its safety.

Acetaminophen is one of the oldest and most widely used drugs in the medicine cabinet, having been discovered in the late 1800s and formally released on the market in the 1950s. Though it’s long since become a generic drug, it’s most well known by the brand name Tylenol. Outside of the U.S., acetaminophen is typically called paracetamol.

It’s primarily used to treat mild to moderate pain, though it may offer some relief for fever as well. While other drugs, like non-steroidal anti-inflammatory drugs (ibuprofen, for example) or aspirin, have advantages over acetaminophen, the drug still has many uses. One use has been for pregnant people specifically, since it’s thought to be safer than any other pain reliever all throughout the pregnancy. Only low doses of aspirin are recommended during pregnancy, though it may help prevent a blood pressure complication called preeclampsia for high-risk individuals, while NSAIDs are only supposed to be taken before the 20th week of gestation, since it may raise the risk of kidney problems for the fetus.

Some studies over the years have suggested that acetaminophen may have its own unique risks during pregnancy. And in an article published Thursday in Nature Reviews Endocrinology, some scientists are now saying that enough evidence has been accumulated that these potential risks have to be taken more seriously.

Summarizing and citing various animal and population studies, they argue that acetaminophen use during pregnancy could alter fetal development, mainly through the drug or its byproducts acting as a hormone-disrupting chemical. This disruption could then increase the risk of some neurodevelopmental and reproductive disorders, as well as genital defects.

“Based on this experimental and epidemiological literature, we believe the potential for harm from continued inaction exceeds the harm that might arise from precautionary action,” the authors wrote.

The scientists, 13 in total, are from many countries, including the U.S., Canada, UK, Brazil, and Denmark. And they all have relevant expertise in public health or gynecology. They also claim that 91 scientists, clinicians, and public health researchers have signed onto their consensus statement.

The group isn’t saying that acetaminophen should be banned for pregnant people, and they rightly note that it’s the only front-line option available for treating pain and fever near the end of pregnancy, which are important conditions that shouldn’t be ignored. For now, they’re recommending only that doctors and patients be more aware of these possible risks and try to minimize the drug’s use and duration whenever they can—advice that the authors acknowledge that many pregnant people might receive anyway.

But they’re also pushing for scientists to conduct new studies on acetaminophen, preferably studies that try to account for things like genetics and other confounding factors. They want regulators like the Food and Drug Administration and the European Medicines Agency as well as relevant gynecological organizations to review the latest evidence and update their current guidelines. And they’re calling for warning labels concerning pregnancy to be placed on all acetaminophen products and for countries to even explore only selling them at pharmacies, as some places do now.

Some outside scientists have already expressed disagreement with the statement, arguing that the evidence for any possible harm from acetaminophen isn’t as strong as the group claims it to be. Time will tell whether FDA and others take this advice seriously. But the group says they felt obligated to speak out now, given how many people use these painkillers and the potential risks of not doing anything at all.

“We here recognize our professional and social responsibility to take this action, even in the face of uncertainty, in light of the serious consequences of inaction,” they wrote.