It's no surprise to many people with irritable bowel syndrome (IBS) that alcohol such as beer, wine, or mixed drinks can set off symptoms. Mixed drinks may contain carbonated beverages or caffeine which can trigger an IBS attack. The tannins in wine and the complex carbohydrates in beer may also pose problems. Additionally, some medications used for IBS can increase the intoxicating effects.
The ability to tolerate alcohol varies widely between people with IBS. Some may not be able to drink any alcohol, while others may be able to tolerate a glass of wine with their dinner. Drinking to excess is, of course, going to be a bad idea for anyone with IBS or other health problems. If you must drink, do so in moderation and during a meal (not on an empty stomach).