Is lemon and cucumber water cause anxiety?

No, it is fine: Depending on the health of your gastrointestinal organs, it might give you a bit of heartburn or acid reflux - but if you've a healthy strong stomach, it sounds fine - even refreshing! Anxiety would not be caused by either ingredient. But, if you don't like the after effects - don't drink it. Find other Vitamin C sources. Don't worry - you did not do any harm to yourself.

I don't think so: I think your anxiety is coming from a different place.