[Idiom] Not touching the sides

[Pepita]

Hi,

what does not touching the sides mean in the following context?
A person had some liquid morphine a couple of hours ago as well as the tablets.
They don't seem to be touching the sides.

Does this mean the medicines are not working?

Can anybody help me with this?
Thanks in advance

 

[Tdol]

There wasn't enough to have much of an effect.

 

[Pepita]

Thank you for your answer, Tdol!

Now I understand the sentence correctly
and see the point in "the sides".

Greetings and have a nice Sunday )