A medicated module for an injection system to co-deliver at least two medicaments is disclosed where a primary delivery device containing a primary medicament accepts a medicated module containing a single dose of a secondary medicament and where both medicaments are delivered through a hollow needle. The medicated module does not require the user to manually engage a reservoir containing the secondary medicament. Instead, a rotating housing automatically activates the reservoir when the needle guard is retracted. The needle guard prevents accidental needle sticks after an injection, and locks after dose delivery.