There were delays of around 90 minutes on the motorway southbound between Junction 15 for Stoke and Junction 13 for Stafford due to the collision.
Nobody was seriously injured.
Highways West Midlands restricted traffic to one lane to allow vehicles to pass the scene as emergency services dealt with the incident but the road is now back fully open.
Police, paramedics and firefighters were all sent to the scene.
A spokesman for the ambulance service said 43 people from the coach had been assessed and nine patients were treated for "relatively minor injuries".
Only one elderly woman needed hospital treatment.
M6 UPDATE— West Midlands Ambulance Service #HelpUsHelpYou (@OFFICIALWMAS) September 13, 2019
3 ambulances, 2 paramedic officers & @WMASHART on scene. Approx. 40 people from coach have been assessed, nine patients in total receiving treatment for relatively minor injuries. Passengers being moved to new coach.
Thanks for your patience if you're stuck on M6. https://t.co/H6XzMJItXL
The spokeswoman said: : “The emergency services arrived to find a coach which had collided with a lorry.
“A total of 43 people from the coach were assessed by ambulance staff on scene.
"Eight elderly patients suffered minor injuries and were discharged on scene.
"A ninth patient, an elderly woman, was given treatment by ambulance staff for injuries not believed to be serious before she was taken to New Cross Hospital for further checks.
“The coach passengers were safely moved off the damaged vehicle and onto a replacement coach, with help from all three emergency services, so that they could continue their journey.”
Three ambulances, two paramedic officers and Hazardous Area Response Team paramedics were sent to the scene.
It comes two days after a nearby stretch of the motorway was completely shut for more than 10 hours after a lorry overturned, crashed through the central reservation and caught fire.