Is the consumption of saline harmful?

To @Madzia:

Mistakenly drinking 4 ampoules of saline (sodium chloride at a concentration of 0.9%) for 2-
A summer child does not pose any health risk.

Saline at a concentration of 0.9% is an isotonic solution, which means that it has a similar salt concentration as body fluids in the body, so it is safe for use in contact with the body, e.g. to moisturize the eyes, wash wounds or inhale. The volume of 4 ampoules is usually a small amount – depending on the size of the ampoule, it can be, for example, 5 ml each, which means that the child could drink about 20 ml of saline solution.

What if a 2-year-old child drank 4 ampoules of saline?