NOT the larger branded liter bottles that waterboys bring out, or that are stored behind the posts, but the little clear bottles only the medical staff dispense.
I've seen it a few times, but most recently in the Springbok vs. Scotland test match (6/28/2014), and although it's more or less out in plain sight, the trainers and injured players seem to have an air of surreptitiousness about it – like it's not entirely above-board, or to be discussed.
I've only ever seen it given to injured players – or players feigning injury because of exhaustion in the last quarter, and they only take one quick gulp.
I suspect it's an elixir of Squirt soda with about 40 Prednisone tablets, NoDoz, and anti-inflamitories dissolved in it, but does anyone know the true content?
A guy broke his leg with a compound fracture in the Rebels vs. Reds match (6/27/14) in Super Rugby.
The announcers commented on the medical team dispensing pain medicine in the form of a “green whistle” (“When they bring that out you know it's serious.”) The player inhaled from it maybe 20 times, so perhaps it's like the gas dentists use. And they had to wait a few minutes for it to take effect before they moved him to the stretcher.
This is secondary and informational to the original question for supplements given to players who continue with play.
Later in the same game an uninjured Rebel player accepts a pill and takes it.