- Guarana preparations and drinks are tonics that counteract fatigue. The product is used to some extent to help support mild diarrhoea, functional asthenia (a technical term for diminishing strength and energy) and as supportive product in weight loss programmes. Traditionally it is a tonic and potential aphrodisiac. The main use nowadays is as an ingredient of fizzy soft drinks (known as guaran or cuparia) that are extremely popular in South America. In recent years, these "energy drinks"