Reminding-Pill / pill

Such occurrences mostly happened at home. This Reminding-Expired-Pill has special design, which operates a colour-changing-method. One month before the pills are getting expired, the opening area of tin foil will transform its original colour slowly into a completely dark grey colour gradually. The medicine is able to take during the tin foil's colour transformation, but it warns and reminds customers the pills are getting expired soon. It is strictly forbidden to take the medicine, when the tin foil has turn into a completely dark grey colour.