We have been on over 30 cruises. From our first cruise we have always brought a small zip bag with the following. Tylenol, Motrin, Sudafed, Benadryl, Imodium, Laxative, Zyrtec, Zicam, Ginger capsules, Liquid IV, throat lozengers, antacid, daytime and nighttime cold capsules.
Hydrocortisone cream, first aid cream, Anbesol, Arnicare, Prep H, alcohol wipes, band-aids, steri-strips, ace bandage and stuff to use if a crown or filling come off. Post covid we have also added a thermometer and pulse oximeter.
Believe it or not all of this fits in a very small bag. I would rather have it not need it then not have it when I need it.