Going through some troubles with laundry soap or maybe shower gel here, I'll second the clangers regarding packing some laundry / toiletry stuff to tide you over or fall back on in case you can't find something that agrees with you here.
Also though, I'll go in with everyone else regarding basic medication like paracetamol / tylenol and allergy meds because they really are *that much* more expensive here.
Among things missed from back in the old country (
) are pillows and other bedding items, particularly as we come toward summer time as here you get fitted sheets (microfiber, satin'ish and jersey knit) and then douvet / pillowcase sets rather than fitted and flat sheets with pillow cases. I miss my flat sheets and actually, crisp cotton sheets in general. (Empty douvet cover works in a pinch, but still...)
Kitchen items also such as favorite jams (no concord grape that I've found at normal groceries here), brown sugar (here but different, scarce and expensive in comparison), oatmeal (different or expensive), cake flour, "good sized" bottles of pure vanilla extract (I believe can be found but expensive and scarce). All these things can be had but often at 2 or 3 (or more!) times the cost that I was accustomed to paying before, not necessities but "nice to have" for sure.