Abstract: Disclosed is an indicator cap for indicating each time a bottle is opened and re-closed having an outer cover shaped in the manner of a conventional bottle cap with a window in the top piece of the cap. The cap is designed to be attached to the sealing cap of the container such that some motion can occur between the two caps during opening and closing of the container, and this lost motion drive is used to advance the indicator. Underneath the window, and within the body of the device, is an indicator wheel having numbers, days, times, etc. engraved or printed thereon which are visible through the window to indicate the next time a dose of the medication should be taken. The indicator wheel contains a pawl formed therein or attached thereto that engages a set of teeth, formed in the underside of the top piece of the outer cover, only when the device is being opened. This engagement causes the indicator wheel to move to the next index location each time the cap is opened.