For those of us with a mental illness, emotional trauma, or an addiction, distorted thinking, distorted perception, racing thoughts, and triggers that cause traumatic emotional memories to be released can turn a seemingly minor or innocuous situation into a harrowing, torturous experience to us.
The most important thing we can do is to apply the recovery tools that we have to lower the anxiety. Having those around us invalidate our feeling/state of being because it was triggered by something that they consider to be irrational is demeaning and counter-productive.
Listening and helping the one suffering the anxiety apply their tools or get in touch with a peer or professional is the most loving thing you can do.