Penicillin is a cocktail that combines blended Scotch, honey-ginger syrup, fresh lemon juice, and Islay single malt. The cocktail is made by combining blended Scotch, syrup, and lemon juice in a shaker filled with ice. When shaken, the combination is strained into a glass filled with ice—preferably one large ice cube—and it is then topped with Islay Scotch.