Are you suppose to inject sterile water intramuscular or subcutaneous?Me and my fellow classmates administered injections to each other in class...

Sterile water for injection is used to mix medications
that are given intravenously. IM or SQ routes are contraindicated. If a product is
needed for IM or SQ use that product should be NS(normal saline). However, NS is also
used as a diluent for IV medications also.

The pH of
sterile water is between 5.5-7.0, this is probably why it burned assuming you gave each
other SQ or IM shots. The pH of your blood is between 7.35-7.45, so the sterile water is
more acidic.

Nevertheless, the amount that you administered
to each other was hopefully very small, probably less than 1ml. You may have had a
local, self limiting reaction to the sterile water.