This may not apply to everyone on the forum, but my HA is an extension of mild OCD. I consider all of the following behaviors to be "reassurance seeking" behaviors that I try very, very hard to avoid. It's tough but my anxiety does lessen when I try to keep from doing them:
1) Actively scanning my body for pain, nausea, lumps, bumps, bruises, etc.
2) Calling my doctor's office to speak to a nurse.
3) Calling my health insurance company's Nurse Line for reassurance. (If your symptoms are even borderline questionable they advise you to go to the hospital as a CYA thing).
4) Visiting an urgent care center. (I do this way too often).
5) Visiting an ER department (I'm better about this. We've lived in the same town for 17 years and although I've been tempted, I've never had to go to the ER).
6) Seeking reassurance from family and friends. ("I'm okay, right? You'd tell me if you thought anything was wrong?")
7) Googlilng or researching any symptoms I'm experiencing. (This is my most troublesome compulsion. If I'm not online researching, I feel like the cancer monster is going to jump out from behind a door and tackle me.)
What works for me most of the time is a delaying tactic. I tell myself I can get online and do some research but first I need to do something else for 30 minutes: A quick workout, working on a crochet project, reading a chapter in a book, walking outside and sitting in the sun, basically anything that does NOT involve the computer because it's too easy to open another tab. Telling myself I can't research at all sends my anxiety spiraling out of control. Thirty minutes of a different activity is usually enough to get my mind going in a better direction. Good luck!