Abstract: A bottle cap is adapted to retain a quantity of an additive, such as, e.g., aspirin, vitamins, nutritional supplements or the like. The additive is retained in an isolated condition within a sealed chamber within the bottle cap but in fluid communication with the liquid within the bottle, such as water. A cap with at least one downward extending cutter is provided to breech the seal of the chamber, thereby releasing some, or all, of the additive retained within the bottle cap. The cap comprises an outer cap member installed over a lower cap member in rotational sealed relationship. A penetrable membrane is located at the lower portion of the lower cap to define a storage chamber for holding a desired additive. A modified J-channel governs movement of the outer cap relative to the inner cap to cause the cutter to move downward and pierce the membrane.