Mood disorders

Lithium: levels, toxicity, interactions and monitoring

The target levels, how to time the blood draw, the signs of early and severe toxicity, the drugs that raise the level, and the long-term monitoring.

9 min read·core·

Reviewed by a licensed nurse · 25 October 2026

Level and what it means

Level (mEq/L)	Meaning
0.6 to 1.0	Common maintenance range
0.8 to 1.2	Usual range for acute mania
Above 1.5	Toxic. Hold the dose and evaluate.
Above 2.0	Severe toxicity. Emergency care, consider dialysis.

Target ranges differ slightly between references and laboratories. Use the local range.

·Mild: fine tremor is expected. A coarse tremor, nausea, vomiting and diarrhea are warning signs.
·Moderate: unsteady gait, slurred speech, muscle twitching, drowsiness.
·Severe: confusion, seizures, coma, arrhythmias.
·Chronic toxicity can occur with a level that is only modestly high.

01
Before starting
Creatinine or eGFR, electrolytes, calcium, thyroid function, a pregnancy test where relevant, and an ECG for patients over 40 or with cardiac risk.
02
After starting or changing the dose
Lithium level about 5 days later as a 12-hour trough, then repeat until stable.
03
Long term
Level, creatinine, TSH and calcium on a regular schedule, commonly every 3 to 6 months, and after any new drug or illness that causes dehydration.
04
Teach
Keep fluid and salt intake steady. Stop and call for vomiting, diarrhea, fever, heavy sweating or new tremor and unsteadiness.

·Hypothyroidism and goiter.
·Nephrogenic diabetes insipidus: thirst and large urine volume.
·Reduced kidney function with long exposure.
·Hyperparathyroidism with raised calcium.
·Teratogenic risk in the first trimester, so contraception counseling and a risk-benefit discussion are needed.

Check yourself

1. A patient taking lithium 900 mg daily starts ibuprofen for knee pain and returns with coarse tremor, vomiting and unsteady gait. What is the most likely cause?
2. When should a lithium level be drawn?
3. Which advice is best for a patient starting lithium?