Not yet. Balloon currently uses a set list of symptoms, and you can’t add, rename, reorder, enable, or disable symptoms.
The screenshot below shows the symptom tracking screen and the symptoms currently available.
We know a custom symptom list would make tracking more useful for many people, and it’s something we’d like to support in the future. If there is a symptom you want to track, let us know through the chat so we can include your feedback as we plan improvements.