Question: Why Do Gin and Tonics Give Heartburn?
By: Colin Saunders
Published: January 21, 2010

Should I switch to soda?

Answers:
Colin Saunders

Perhaps you should, tonic is the best way to ruin a decent gin. You might also think of switching to gin and distilled water.
Euclydes Antoni...

Perhaps you should switch to water only, as alcohol in general increases acid production in the stomach and has a relaxing effect over the cardia (the valve avoiding reflux of the stomach contents to the esophagous), the main causes of heartburns.
Marisa

I don't think soda will solve your problem. As far as I know carbonated drinks in general should be avoided if you're prone to heartburn.