What would happen if a bacteriophage entered the human body?

Our immune system is designed to recognize /anything/ that's not in our body. So I think that if you put in the bacteriophage, it would probably get digested (it's not enveloped, just a capsid, which is entirely protein and thus easily digested in the mouth, then the gut). Once in the gut, if it's not completely broken down, i'd imagine that the bacteriophage would probably try to attack the fauna within the gut (try to replicate) but the galt system in the gut (an immune pathway which stores a ton of memory  B cells would destor it in a heartbeat. Otherwise, if it's not attacked, it would just add to the ecology of your gut.

We have essential bacteria in our mouths, throat, stomach, kidneys so on and so forth. A bacteriophage can attack any of these bacteria and kill them. For example if this happened to the important bacteria in the digestive tract digestion, and nutrient absorption would be greatly affected. Take this analogy, a infectious bacteria is to a human as a bacteriophage is to vital bacteria. That should clear things up.