Hi Ripplegirl99

The therapeutic:toxic ratio of lithium as treatment for Bipolar Disorder is quite narrow.

That means that too little won't help and too much is potentially toxic.

I suggest that you encourage your friend to get her doctor to arrange for regular measurements of her blood lithium levels (frequently if she has only been on it for a short time, less frequently if she has been on it for a while).

Depending on the results of those measurements, it may be necessary to change her lithium dose up or down, keeping its blood level in the therapeutic range.