A presidential spokesman, Jung Youn-kuk, insisted that there was a perfectly innocent explanation. Besides the more common bedroom use, the pills are sometimes taken to prevent or treat altitude sickness. Mr. Jung said doctors had prescribed them for presidential aides to have handy for that purpose during Ms. Park’s official visit in May to Ethiopia, Kenya and Uganda. (Those countries’ capitals are all well above sea level — Addis Ababa’s elevation is 7,700 feet.) As it happened, Mr. Jung said, none of the pills were used on the trip.

Ms. Park has never married, and her private life has been the subject of scrutiny for years. After the ferry Sewol sank in 2014, killing more than 300 people, rumors spread that she had been in a tryst with a boyfriend for seven hours, making her government slow to respond effectively to the disaster. Her office vehemently denied the rumor, and a Japanese journalist who reported it was indicted on defamation charges. (He was later acquitted.)

Other items on the Blue House’s pharmacy tab also drew unwelcome attention on Wednesday, including large volumes of nutritional compounds that wealthy South Korean women have often injected to fight fatigue, aging and skin problems. The presidential office said those items were for staff members, but that did not stop online commentators from accusing Ms. Park of squandering tax money on skin care.

None of this was much help to Ms. Park, who has been struggling with the corruption scandal for weeks. It centers on Choi Soon-sil, a close friend of Ms. Park for decades, who has been arrested on charges of leveraging her influence to extort millions of dollars from businesses.

Prosecutors said on Sunday that Ms. Park was an accomplice in the alleged extortion, and two former presidential aides have also been indicted on charges of aiding Ms. Choi and providing her with confidential government documents.