Liqueur, Love it or feel the burn?

In keeping with my last Alcohol related post.

I am also a big fan of all sorts of liqueurs, (great for sipping) but, and here's the but...

Is it just me, or does anyone else find the extremely high volume of sugar cause a surge in stomach acid. I mean two shots and I find myself running for the Prevacid? I can drink plenty. Even 'Everclear' with not much issue, but liqueurs (as much as I love them) don't love me so much back. And if so am I right to assume the sugar as the cause?. After all most liqueurs are like syrup.