Ale vera juices are commonly made from grounded leaves dissolved in water. They are packed and sold as health tonic. However three of the species including Aloe vera are not safe to drink and even banned by law in Japan.
However one can drink Aloe arborescence juices provided they are made hygenically and properly.

Juices made from leaves of three Aloe species Aloe vera , Aloe ferox and Aloe africana are not allowed to be used as food according to pharmaceutical affairs law in Japan while Aloe arborescens can be used as food. Thus its not safe to use Aloe vera juices as drink.
see also
Gullerman and Chauser Volfson 2008, (Bhansali and Kumar 2009 in press)