I don't think vitamins have much, if any, carbs. And Dr. Atkins recommended them in his book. And for me too, they never affected my ketosis or weight-loss. I was mainly concerned with the vitamins found in fruit, mainly Vitamin C, since no fruit was eaten for so long.
But in terms of pharmaceutical items...what WOULD probably contain sugar and carbs would be any sort of flavored liquid medication...like cough syrup (though they do make sugar-free versions of some of them)...or flavored liquid laxatives or flavored fiber/psyllium items, etc. Another thing that would be a problem would be any sort of enteric-coated pill. If you put an enteric coated pill in your mouth you can usually taste the sweetness right away. Pills that are enteric-coated have a coating like an M&M, more or less. And also flavored tablets like flavored Tums and other items like that for indigestion.