Allergan PLC is recalling one lot of the birth control Taytulla because the first four days of the therapy erroneously placed placebo pills where contraceptive capsules should have been. The out-of-order pills might not be evident to women using the product, including previous users and new users, and thus could result in unintended pregnancy. Patients concerned about this should consult their doctor, Allergan said. The packaging error affected one lot of Taytulla, according to Allergan, a “physicians sample pack” that was distributed nationwide. (The lot, numbered 5620706, contains 28 pills and expires in May 2019.) The issue was discovered because of a physician report, Allergan said. Birth control pills must be taken faithfully each day in order to work effectively, experts say; one reproductive health professor told MarketWatch last year, “it only takes missing a couple of birth control pills for a person to become pregnant.” Allergan shares declined 0.7% premarket. Shares have slumped 0.14% over the last three months, compared with a 0.3% rise in the S&P 500 and a 1.1% drop in the Dow Jones Industrial Average .