The longer you are on the lithium the less often you need a blood test. If you have only been on it a few months it is not unusual to get a blood test every 2 to 3 weeks, until your doctor is sure your level is steady with the dose you are taking.

It is always better to get more tests than less as toxicity is dangerous. I was toxic once when my pharmacist changed my capsules from 300mg to 600mg. I had been taking 2 capsules a day and continued to do so. Instead of taking 600mg a day I was accidentally taking 1200mg a day. I started having large muscle tremors (threw a cup of coffee once), couldn't look up the hospital's number in the phone book because I couldn't remember the alphabet, diarrhea, vomiting, couldn't remember my date of birth when asked by the doctor in the ER, couldn't walk unassisted. Like Deiota, I drank huge amounts of water which helped to bring my level down so that I didn't do permanent damage to any of my organs. I was on an IV for 5 days to get back into the therapeutic range.