Flying 2017 Cirrus SR-20 N698SL, Minneapolis Flying Cloud (KFCM), August 2018.
Short introductory flight. Run-up, Taxi, Takeoff, Landing, and Taxi back to parking. Passenger door was closed, but not properly latched. Door secured inflight after takeoff. If the door were open, or this were a longed flight, I would have advised the tower and returned for an immediate landing to reset the door. For future flights I will be sure to provide more detailed passenger briefings to include both opening and closing the doors, and double checking the doors are latched prior to takeoff. Passenger became uncomfortable during landing, airsick bag at the ready. Safe landing, airsick bag unused.