What is the common garnish for drinks containing tonic?

The common garnish for drinks containing tonic is a slice or wedge of lime. This choice is favored because lime adds a bright, zesty flavor that complements the bitterness of tonic water. Tonic water itself has a distinctive taste due to the quinine it contains, and the acidity and freshness of lime enhance that flavor profile, making the overall drink more balanced and refreshing.

Using lime as a garnish also aligns with traditional cocktail practices, especially for well-known cocktails such as the gin and tonic, where the lime serves not only as a garnish but also as an ingredient that elevates the drink's character. While other garnishes like cherries, lemon slices, or mint sprigs have their own uses in different contexts or cocktails, lime specifically is the classic pairing for drinks featuring tonic.