Unfortunately smoking does affects the amount of duloxetine in your system and blood stream meaning that you will loose between 40 - 50% of the duloxetine dose you take. It is not uncommon for people to have their duloxetine prescription increased if they smoke. Unfortunately it is not uncommon if you miss a dose to be experiencing these problems if your on a high dose, my patients even at a dose of 30mg do experience brain zaps, nausea and vomiting even with just one day missed even more so if you suffer with fibro pain, This is why duloxetine should be withdrawn extremely slowly and only under professional help