If you recently quit smoking and started to vape, you should know that the cough is not exactly a bad sign. When you stop smoking the lungs begin a cleansing process and mucus and impurities are eliminated from the lungs through coughing.

Another reason can be the PG concentration of your e-liquid. PG is classed as a humectant, meaning it retains water, which might cause a dry throat. It is recommended you drink more water, and if the problem still persists, you could try doing a PG allergy test.
However, coughing symptoms tend to disappear in a few weeks, once the organism gets used to not being bombarded with the thousands of chemical substances found in tobacco. When you quit smoking, your body goes through a lot of changes, especially if you have been an avid smoker. The cleansing process can be very lengthy and sometimes even unpleasant.