A medicated module (4) 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 (4) containing a single dose of a secondary medicament and where both medicaments are delivered through a hollow needle (3). The medicated module (4) does not require the user to manually engage a reservoir (22) containing the secondary medicament. Instead, a biasing member (48) automatically activates the reservoir (22) when the needle guard (42) is retracted. The needle guard (42) prevents accidental needle sticks before and after an injection, and locks after dose delivery.