Almond milk will most likely not flare up any IBS symptoms. However, if the almond milk you have is sweetened and has thickeners/preservatives, you are more likely to experience an IBS flare-up.
Jesse Feder suggests having almond milk with limited ingredients, preferably almonds, filtered water, and added vitamins. He adds, “I treat clients with IBS, and they have had flare-ups from certain almond milk with these added thickeners/preservatives. After they switched to almond milk without them, they have told me they have yet to experience any IBS flare-ups from their almond milk.”