Slug & Jiggers Apothecary is the primary potion ingredient shop located in Diagon Alley. From the outside, the shop is described as fascinating. Inside, it is filled with a strong, unpleasant smell, which Harry Potter likens to a mixture of bad eggs and rotted cabbages. The interior of the apothecary is densely packed with a vast array of ingredients. Barrels of slimy substances line the floor, while the shelves are crowded with jars of herbs, dried roots, and shimmering powders. Hanging from the ceiling are bundles of feathers, strings of fangs, and tangled claws. Specific items noted for sale include silver unicorn horns at twenty-one Galleons each and minuscule, glittery-black Beetle Eyes at five Knuts a scoop. The shop serves the broader wizarding community, including students from Hogwarts School of Witchcraft and Wizardry who need to purchase ingredients for their Potions classes. It is also frequented by accomplished potioneers like Horace Slughorn, who once complained to the proprietor about the “outrageous prices” for some of his favoured ingredients. This implies the shop stocks rare and expensive components necessary for advanced and complex potions, such as the Bicorn Horn and Boomslang Skin required for the Polyjuice Potion.
Slug & Jiggers Apothecary is one of the first magical establishments Harry Potter encounters, and it plays a crucial role in establishing the practical and commercial side of the Wizarding world. It demonstrates that magic, particularly the art of Potions, relies on tangible, and often bizarre, components that must be sourced and purchased. The shop serves as a recurring background element that reinforces the authenticity of Diagon Alley as a magical high street. While no major plot events occur inside the apothecary itself, its existence is fundamental to the logic of the magical world. When Hermione Granger needed to brew Polyjuice Potion, she was forced to steal the necessary ingredients from Severus Snape's private stores because they were not available in the standard student cupboard, highlighting that a specialized shop like Slug & Jiggers is the proper commercial source for such items. The mention by Horace Slughorn further solidifies its reputation as the go-to supplier for even the most expert witches and wizards.