For me it’s anything suddenly noisy. 
I was outside enjoying the calm sun…and a fly happened to buzz next to me. It startled me and I panicked and had an anxiety attack that didn’t go away so I had to take my benzos. 

When I get bad anxiety I start getting palpitations and then I feel like the ground is sinking. I get tunnel vision and my face starts to get completely numb as well as my hands. I feel like a fish without water.