On this page of the Valheim game guide, you will learn how to induce vomiting in your characters.
Vomiting is a mechanic that was added to the game in the Hearth and Home update. It allows you to immediately empty your stomach and eat more types of food. This is especially useful when you suddenly need more stamina instead of a lot of HP.
To induce vomiting, you will need bukeberries. Upon eating them, the contents of your characters' stomachs will see the light of day. These "fruits" can be obtained by defeating greydwarf shamans and brutes. These creatures can be encountered in the Black Forest biome, especially during the night.