It takes about 6 oranges to make one cup of orange juice. You wouldn't sit and eat 6 oranges, would you?
That is the thing about juice, is that it takes a lot of a fruit to make the juice. Fruit alone has a lot of sugar, so when you consume something like juice that involves using a LOT of a fruit, you are going to be consuming a lot of sugar, most of which could get stored as fat.
You are better off limiting it to about a cup per day, or getting your vitamin C from the oranges themselves and drinking mostly water.
If you like fruit juices, you could always go for 100% unsweetened cranberry juice. Very tart but it is lower in sugar.
Don't od on vitamin c (it won't kill you but you will be running to the bathroom a lot if you do). other than that try not to let the acid be on your teeth too much. You can do what other people suggested and/or drink through a straw.
Is it orange juice you make yourself? Or the kind you buy at the store? Because regular oranges freshly squeezed into a glass would be good for you...lot of vitamin C. Maybe 2 glasses. But I think if you have too much, you'd be taking in a lot of acid...
A lot of people are commenting WRONG information. Sugar from a fruit is completely different than sugar from a sugar cane. However, in orange juice they tend to add the wrong type of sugar (from sugar cane) which can make too much orange juice of most kinds (there's some kinds that don't use sugar) a bad thing.
Also, the acid can be pretty hard on your teeth. Try to limit your orange juice and make sure you get some plain water too.
If it irritates your bowels (and you'll know it because you have all too frequent bowel movements) then slow down your intake. Besides that, OJ in large quantities is a lot of sugar, and too much of that is not good unless you're always on the move (exercising, walking, etc.)
However, it is better to eat the whole orange instead because you miss out on nutrients by just drinking the juice. Some of the vits/minerals are attached to the inner skin of the orange.
I think it's bad for your teeth because of the high acid content and depending on what kind you drink the sugar content could be really high so that would be bad too, especially if it is from concentrate.
Well in addition to what other said about the teeth, diabetes, and acid reflux, orange juice because of vitamin C, which is a co factor that can interfere with certain medications so I know that can be bad. Also its bad if all your drinking is orange juice without calcium and vit D.