High PG ratio juices and high Nicotine level juices will sometimes make me cough... especially in the mornings or if I've not had enough water to drink during the day (dry throat to start with). Even my dripper (running 50/50 PG/VG @ 6mg nicotine) will make me cough from time to time, especially if I take a full lung-hit, rather than my usual mouth-to-lung hits, like I do on my tanks.
Analogs have an anesthetic effect... they numb the throat and bronchial tubes, which reduce coughing and the burning effect of all those toxins entering your body (yes, another evil device of big-tobacco to keep you smoking), which is why smoking with a sore-throat always felt so good... and if you think about it... your first analog of the day usually made you cough, but the second, third... twentieth of the day didn't!
Changing to a higher VG content of your juice, drinking more water, and changing to mouth-to-lung draws will reduce your urge to cough (usually).
It could be the way you're vaping. Try taking a shallow draw into your mouth, hold it just a bare second before inhaling. Vaping, while similar to smoking, is a little different. You just need to readjust how you're doing it. Once you get used to it, you can readjust the way you vape to suit yourself.
