"First pus and now this."
Seamus Finnigan, when discovering that he had to feed Blast-Ended Skrewts after handling Bubotuber pus[src]

Bubotuber pus is the liquid found in the swellings of the magical Bubotuber plant. It is very valuable for its acne-ridding qualities. It is a thick, yellowish-green liquid and smells strongly of petrol.

Despite retaining healing powers, when undiluted it can cause painful, large, yellow boils to form immediately on the skin, and dragon-hide gloves are recommended to be worn while handling it. It is also an excellent remedy for the more severe cases of acne, and is recommended in preference to spells, which can backfire and cause side effects as extreme as nose loss, which happened to Eloise Midgen.

Bubotuber pus is collected by squeezing the swellings on the plant, and catching the pus that bursts out in bottles. In 1994, the Fourth years attending Hogwarts collected Bubotuber pus in bottles during Herbology with Professor Sprout. When the students were squeezing the swellings, it was described as "disgusting, but oddly satisfying."

In the same year, Hermione Granger was sent an envelope from an unknown person, who believed the rumour that she had relationships with both Harry Potter and Viktor Krum, as reported by Rita Skeeter. This caused yellow boils to form on her hands, which made it looked like she was wearing thick, knobbly gloves.

In 1996, Molly Weasley mentioned that a mixture of gravy and Bubotuber pus was being falsely sold as a Protective Potion against Lord Voldemort, despite having no effect on Dark wizards whatsoever.

The pimple-curing properties of Bubotuber pus was discovered by Sacharissa Tugwood, who also created some of the earliest Beautifying Potions.