Almost 170,000 birth control pill packs are being recalled over a manufacturing error that could lead to unplanned pregnancy, maker Allergan says.

Taytulla physician sample packs include active capsules and inactive placebos that are designed to be taken in a certain order. The recalled packs may have been packaged out of order, so that a person who expected to take an active capsule may actually take a placebo, CBS News reported.

Allergan said the error was isolated to a single pack, but the entire lot was recalled as a precaution. The packs are marked with lot number 5620706 and an expiration date of May 2019, CBS News said. The network reported Allergan would notify users by letter.

"If patients have concerns regarding the possibility of an unintended pregnancy, they should consult their physician," Allergan said in a recall statement posted by the U.S. Food and Drug Administration.

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