Is it okay, for an adult, to drink soy bean milk when he/she is having diarrhea?

Diarrhea, soy milk: I don't think drinking soy milk will make the diarrhea worse, but it may be better to stick with water for a few days until the diarrhea clears up. Cow milk will likely make things worse, so avoid that. You need extra water when you have diarrhea to make up for the fluids you are losing. Eat a simple diet of rice or bread, bananas, chicken broth. If you have bloody diarrhea/fevers, see a doctor.