The  FDA is approving new drugs so fast that companies are now preparing for a green light months in advance of the scheduled decision date, a pace that’s helping patients with rare or untreatable diseases but raising alarm among consumer advocates.

Global Blood Therapeutics Inc., maker of a new sickle cell disease drug called Oxbryta, built a booth to showcase the medicine at the annual meeting of the American Society of Hematology that begins this weekend — even though the Food and Drug Administration’s deadline for approval was Feb. 26.

The move paid off: Oxbryta was given the go-ahead by the FDA on Nov. 25, almost three months ahead of schedule, and the branded booth will make its debut at the ASH conference in Orlando, Florida, on Saturday.

Oxbryta’s approval added to a growing number of breakthrough products that have beaten their FDA deadlines by weeks and sometimes months. For normal medicines, the agency typically has 10 months to issue a ruling. For those with exceptional benefits, or that treat conditions with few existing therapies, it offers a priority review that takes just six months. From mid-October to mid-November, the agency approved five medicines in as little as eight weeks.

The shift is emerging as the FDA is approving new drugs at a record pace, and breakthroughs in biotechnology and genetics are enabling drug companies and their scientists to provide more specific data to federal regulators.

But even as drugmakers, investors and patients cheer on the agency’s pace, patient-safety advocates argue that speed comes at a price. Studies show medicines approved on a faster time line are more likely to have safety problems emerge after they become broadly available, while other treatments offer fewer benefits than anticipated.

While the Trump administration has focused on reducing regulation across the U.S., the FDA’s new-found speed had its genesis more than a quarter-century ago. Drugmakers agreed to pay the agency user fees in return for firm deadlines after years of wild guesses. Congress and the FDA layered on programs providing incentives for drug developers to craft products for patient groups with critical unmet needs, especially for rare conditions.

It’s not just speed. The FDA also is approving more drugs, hitting a record 59 new therapies in 2018. Almost three-fourths received a priority review. That, combined with more efficient data collection, is responsible for the faster FDA action, said Aaron Kesselheim, a professor at Harvard Medical School. Companies are also communicating earlier and more often with the agency, which can head off issues at preliminary stages and help them get products through on the first attempt, he said.

Vertex Pharmaceuticals Inc.’s Trikafta, a triple combination of drugs to treat cystic fibrosis, won FDA approval in October, five months earlier than expected. Investors dubbed it an early Christmas gift from the FDA.

Clearance for Novartis AG’s Adakveo, another new medication for sickle cell disease, came in November. It was 62 days ahead of the FDA’s deadline, known as the PDUFA date. BeiGene Ltd.’s Brukinsa was approved three months ahead of schedule for mantle cell lymphoma.