I took Lithium ER on two occasions. The first was six months and it was my very first bipolar medication, along with a smallish dose of Seroquel. The second time was almost five years, and it was with a boat load of other bipolar medications. Both times, it was only marginally helpful for me.

I don't believe I ever had Lithium toxicity, but perhaps close, on a few occasions. The first time I took it, I took 1200 mg. The second, only 900 mg.

Lithium gave me the highest number of side effects of any medication I have ever taken. Some were more serious than others, though. Some were also fleeting/temporary and others constant. Here they are:

1. Mild nausea (only at the beginning)

2. Mild dizziness (only at the beginning)

3. Hand tremors (was very bad on 1200 mg, but barely noticeable at 900 mg at which time I also took propranolol, which reduces them)

4. Polyuria/Polydipsia (extreme frequency of peeing and thirst, sometimes so urgent that I wet myself)

5. Mental cloudiness (I didn't realize how bad this was until after going off Lithium)

6. Hypothyroidism (turned out to be permanent)

7. Cystic acne (Really bad and weird acne after years of not having any - it went away completely about 3 months after being off Lithium. Good news is that even scars that seemed to result from this acne eventually disappeared, but maybe almost a year later.)

8. Temporary hair loss (For a period of a year, my hair was falling out quickly, but luckily I had/have otherwise a huge mop of hair so though it was much less than before, I had no bald spots. This side effect suddenly went away while still on Lithium. It took a couple years for my "mop" to be as full as ever.)

9. Hard finger nails and wirey head hair (The latter was unpleasant, the former an improvement since my nails have otherwise been too soft and thin. Both have since gone back to my pre Lithium norm.)

10. Dry skin and other subtle skin appearance changes (these changes took a while to start and have faded since going off Lithium)

11. Kidney damage (This is why I no longer take Lithium and never will again. The damage is only mild, since my psychiatrist caught it early via a creatinine level test, however it's likely permanent.)

A good thing? Lithium was weight neutral for me. When I was put on Lithium the second time, along with weight neutral Geodon, Lamictal, and Tegretol, I lost 40 lbs in six months on a diet. It was easy to diet at that time. That got me into a normal BMI range, which I mostly stayed within for a few years.