There isn’t really a set limit, but as with any highly nutritious superfood, you want to start with a low quantity to see how your body reacts to it.
It’s generally recommended that you start off with a 1oz shot every day, and then you can build up to larger quantities when you feel like there have been no ill effects or symptoms.
Some people report feeling nauseous when drinking too much wheatgrass in one go, so bear that in mind and go slow in the beginning.
Remember also to drink it on an empty stomach, since this will reduce the likelihood that you experience nausea.
Once you are adjusted to wheatgrass juice, then you can safely drink as much as 2oz every day or a little bit more.