US pharmaceutical giant Pfizer on Tuesday recalled one million packets of birth control pills over a packaging error that could put women at risk of unintended pregnancy.
The pills, about half of which were the brand name Lo/Ovral-28 and the other half were generic norgestrel and ethinyl estradiol tablets, may be improperly arranged so that inactive pills are taken at the wrong time in the monthly cycle.
"An investigation by Pfizer found that some blister packs may contain an inexact count of inert or active ingredient tablets and that the tablets may be out of sequence," Pfizer said in a statement.
"As a result of this packaging error, the daily regimen for these oral contraceptives may be incorrect and could leave women without adequate contraception, and at risk for unintended pregnancy."
The pills were manufactured and packaged by Pfizer in New York state and commercialized by Akrimax Rx Products under the Akrimax brand name in the United States.
Each packet is supposed to contain 21 active tablets and seven inactive pills.
"The cause of the inexact package counts has been identified and corrected," Pfizer spokeswoman Grace Ann Arnold told AFP.
She described the problem as a "mechanical and operator visual inspection systems failure on the packaging line."
Patients who have been taking the affected lot numbers, posted on the US Food and Drug Administration website, should notify their physician, return the product to the pharmacy and begin using a back-up form of non-hormonal birth control right away, Pfizer said.
Gynecologist Jill Rabin at Long Island Jewish Medical Center in New York urged women who have been taking the affected pills to also get a pregnancy test.
"Sequence and content of active vs inactive pills is crucial in determining efficacy, including whether or not unwanted pregnancy will be actually prevented," she said.
"Ensure that you are not currently pregnant by taking a pregnancy test if you have any symptoms of pregnancy, such as missed periods, abnormal bleeding, etc."