Drinking barley juice after abdominal pain may be barley allergy, drinking improperly and so on. 1. Barley allergy: barley juice is a drink made of barley as the main raw material, part of the population is allergic to barley, after drinking the human body may appear a series of allergic reactions, such as patients with abdominal pain, diarrhea, skin rash and other symptoms. 2. Drinking improperly: some patients drink barley juice on an empty stomach and drink a large amount, can increase the burden on the gastrointestinal tract, resulting in abdominal pain, bloating, indigestion and other symptoms. In addition to the above reasons can lead to drinking barley juice after the cause of abdominal pain there are many other causes, the patient should consult a doctor in a timely manner to clarify the cause of the disease, as soon as possible treatment, so as to avoid delays in the condition, resulting in adverse consequences.