Two we are dealing with daily are reflux and pressure sores.
Both my kids had reflux as babies, Samuel took until he was 4 to grow out of his and wean him off his medication. Evelyne's reflux was not as severe as a baby, and it wasn't until we applied the cast that it became much worse and medication was needed. The tightness of the casts and braces squeeze and put pressure on the tummy and can cause the contents to be pushed back into the oesophagus. It is also uncomfortable to eat big meals and I've heard others with spinal braces as teenagers recommend smaller, more frequent meals. At the moment Evelynes reflux is managed with medication, leaving more time between meals and bed, and avoiding some foods close to bedtime.
Pressure sores are also reasonably common on the bony prominences of the kyphosis of the spine (the hump), and sometimes on the hips where the brace or cast sits. Evelyne has a constant red area on her back which occasionally breaks open and requires something like duoderm to dress it. Fortunately in a brace, you can check it and dress it if needed, in a cast often sores are open and remain untreated. In the picture you can see the gel dressing with a groove in it from the brace digging in! (The red area is a birth mark).
Both these issues can be painful for her, but unfortunately, they are the lesser of the two evils. The treatment of her spine and attempting to manage the progression of her scoliosis is more important at this stage. So for now, we attempt to alleviate the symptoms as best we can.