I never had any terrible problems personally with either lithium or lamictal. The lithium kicked in after about a month. Mostly I dealt with thirst (and the constant trips to the restroom because I was always drinking water) and some hand tremors which improved when we went down a bit on the dosage. Lamictal took forever to hit a therapeutic dose for me; had to go up to 400 mg to get there. Some achiness during titration, but that subsided once I go up above 100 mg.

My husband has had trouble with both lithium and lamictal. He went into severe toxicity with lithium despite careful monitoring, went into kidney failure and had to be put on dialysis in the ICU for a week. Very scary time. Needless to say they won't be putting him on lithium again. (Note: he has complicated medical issues so his toxicity was probably tied up with those problems but we probably will never know for sure.)

With lamictal he had severe memory and cognitive problems when the dose got above 100 mg. Once reduced below 100mg those problems improved.