Panicked buyers in stores were reminiscent of the early days when Japan faced mask shortages.
Twitter posts were accompanied by pictures of emptied shelves with handwritten “Out of Stock” notices.
The notices included suggestions on how to acquire the antiseptic believed to be a coronavirus cure.
"Anyone else having trouble buying gargling medicine? I'm coming to four misses now," wrote one user, @shotaro_1117, who posted images of four cleaned-out shelves.
On Tuesday, Osaka Governor Hirofumi Yoshimura said a study showed a smaller viral load in the saliva of 41 patients with mild symptoms after regular gargling with a medicine infused with povidone-iodine solution than in those who had not.
"Perhaps we can even overcome the coronavirus with gargling medicine," he told a mid-afternoon news conference, speaking of the study on those convalescing in regional hotels which was released by an Osaka hospital.
As the Japanese official spoke, shares of Meiji Holdings Co , which sells a popular medicine previously marketed as Isojin, skyrocketed, gaining as much as 7.7 percent by late on Tuesday.