A cap for making a soft drink in a threaded bottle includes an inner cap, an outer cap and a flavor container. The inner cap has external threads and internal threads that match the threads of the mouth of the bottle, and the outer cap has internal threads that match the external threads of the inner cap. The cap includes a first releaser for opening the flavor container into the bottle when the cap is being screwed onto the mouth of the bottle. The cap further includes a carbon dioxide container and a second releaser for opening the carbon dioxide container into the bottle when the outer cap and the inner cap are being screwed relative to each other. The disclosed embodiments also relate to a method for making a soft drink.