This has been asked [before](https://www.reddit.com/r/askscience/comments/3t8ky2/why_does_soda_stop_fizzing_when_you_add_alcohol/), with two answers given:
1. Alcohol is better as dissolving CO2 than water so it can hold onto it better and stop the foaming.
2. Alcohol reduces the overall surface tension of the liquid so bubbles are very small and less stable, and escape more easily
Latest Answers