Severs disease is a common problem of the growing area of the heel bone in children. It is more appropriately called Calcaneal apophysitis as its NOT a disease. As its a problem with the growing plate at the back of the heel bone, it will go away on its own when the growth stops in that bone which is typically around the mid-teenage years. That does not been it can not be helped and has to last that long. It is more common in those who are more active.
Just how long does Severs disease last?
There is no clear answer to this except the one that it will be gone by the mid-teenage years. How quick the pain goes away earlier than that will depend on what treatment is given and how much activity levels are reduced.
Severs disease will get better quicker if there is a greater reduction in the loads or activity levels and it will take longer if activity levels are not reduced by much.
This edition of the video live stream from PodChatLive on Calcaneal apophysitis is well worth a listen to as the hosts speak with an expert on Severs disease. They do address just how long that it lasts.