The guarana berry is originally from the Amazon, but is now also cultivated in Bahia. It has stimulating properties (and a molecular composition) similar to caffeine. There are a couple of different forms you'll find it in.
Energetico/Arrebite: Pharmacies sell it in its liquid form, small pocket size tubes called energeticos. Arrebite is the leading brand, but there are several competitors. You can drink this concentrated liquid right from the tube, or you can add it to water or pour it in your cocktail. I stock up on this stuff before carnival starts and always leave home with a few tubes in my pocket. To make an imprecise and completely unscientific assertion, I would say that one small tube of guarana has the equivalent effect of a shot of espresso. One herbal combination frequently found with these liquid energetico tubes is guarana mixed with catuaba, an herb that acts to increase blood circulation said to have aphrodisiacal properties. Hey, there's a reason you can find these tubes on just about every corner at a pharmacy; they work!!!!
Powdered form: No, you don't snort it, you drink it. You'll encounter it at the street barracas or cocktail stands that are found everywhere during carnival. The cocktail it's traditionally used in is the kapeta, but if you're running low on energy, you can ask the guy making your drink to put a spoonful of this guarana powder in any cocktail you order. For those who prefer to "point" rather than mangle the Lingua Portuguesa, the powder is brownish in color. It has a very bitter taste in powder form, but this is hidden when added to alcohol.
Guaramix: This is a relatively recent addition to the beverage menu found here in Salvador. Guaramix is an energy drink that is water with guarana syrup, açaí, and gingseng added to it. It's taste is similar to a sweet ice tea. Not bad. If you come across it, instead of hydrating with mineral water, why not 'step it up' with a Guaramix.
Açaí: Açaí is a berry from the Amazon that is rich in vitamin, anti-oxidants, and electrolytes. While açaí is served in many forms ranging from energy drinks to ice cream, the most common way you'll find it is by the tigela or bowl, sprinkled with granola. Frozen açaí concentrate is mixed in a blender with ice, banana, and guarana syrup and served cool in a bowl or plastic cup. With a texture like sweet sherbet, some find it an acquired taste, but if you get past your first one, watch out! Açaí has a way of hooking you. Refreshing and re-energizing, açaí is the ultimate hangover medicine. Right off the carnival circuit in Barra on Rua Manuel Barretto (near Shopping Barra), there are a couple of juice bars where you can find açaí in the tigela served 24 hours a day during carnival.