Spanish bitter liqueurs, or "licores amargos," originated much the same as many European bitter liqueurs, evolving from traditional herbal medicine made in medieval monasteries by monks. They would have crafted medicinal tonics from various herbs, roots, and spices, but over time the recipes became more refined and their use shifted from imperative to pleasurable as palatable beverages enjoyed for their complex flavours as much as their digestive properties.
To make Spanish bitter liqueurs, botanicals such as gentian root, wormwood, and citrus peels are typically macerated in a high-proof alcohol base, followed by sweetening with sugar or honey. The mixture can be aged to allow the flavours to meld and develop. They can range from intensely bitter to subtly sweet and are traditionally consumed as aperitifs or digestifs, often served neat or on the rocks.