Can I use my Apple Watch to run Symptrack?

Yes and No. SympTrack needs to be downloaded to your iPhone where you get all the functionality of the app. However, you can get a notification to rate your symptoms at a set time each day on your Apple Watch

Can I compare symptoms against each other?

Yes you can. Tap on ’Tracking’ and then on ‘Compare’. You can select any two symptoms to graph against each other.and select from six different bases to graph the data.