It is a terrific med, I had only been changed to Lamictal for the anti-depressant property it has though Lamictal is not an anti-depressant.
Lithium is great for the mania, helped me to lose a lot of my inner anger, has no sexual side effects.
Like any med it has to be started at low doses and then titrated gradually, and blood levels will need to be done monthly in the begining then over time every 3 to 6 months depending how you are doing during treatment.
Another beauty to it is that you do not get zonked out like I did when I was on Depakote, that stuff zombified me.
It is worth a try, you just may find Lithium is for you.
The one I was on was Lithobid, I think the difference is that is more time released than the other Lithium meds.
My brother takes a different one than what I did and says in the begining he had a metallic taste in his mouth, I never had any ill side effects from the Lithobid, but everyone is different and it also depends on what type bipolar a person is and what level of mania/hypomania and/or depression.
One has to do what fits their need(s) and has the least amount of side effects. Discuss it with your pdoc, also I personally would give it a try, it is safe and has been used for a long time, the patient just needs to take it as prescribed and not fool with that, but that holds true for any med.
I found the only reason most pdocs substitute Lithium with other mood stabilizers is that many of the other types go to work faster which in some cases of extreme mania requires a quick "knock down", oh and of course if they cannot physically tolerate Lithium.
It is a great med and has a long track record

Lots of luck with this

In giving advice seek to help, not please your friend
SOLON