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Uses & FDA Indications

Lithium has been in clinical use for over 70 years and carries robust evidence for bipolar disorder treatment and prevention. It also has an unparalleled evidence base for suicide risk reduction.

FDA-Approved Uses

• Bipolar I disorder, acute manic episodes — treatment of active mania in adults
• Bipolar disorder, maintenance — prevention of future manic and depressive episodes

Off-Label Uses

• Bipolar depression (adjunctive)
• Augmentation of antidepressants in treatment-resistant depression
• Cluster headache prophylaxis
• Suicide risk reduction in mood disorders
• Schizoaffective disorder

How It Works

The precise mechanism of lithium's mood-stabilizing effects is not fully understood, but several key pathways have been identified. Lithium inhibits glycogen synthase kinase-3 (GSK-3β), an enzyme involved in intracellular signaling that plays a role in neuronal plasticity, apoptosis, and circadian rhythms. It also inhibits inositol monophosphatase, depleting inositol and modulating phosphatidylinositol signaling cascades critical to neurotransmitter receptor function.

Lithium modulates serotonin neurotransmission, increasing presynaptic release, and affects norepinephrine turnover. It also has neuroprotective properties, promoting BDNF (brain-derived neurotrophic factor) expression and reducing neuronal apoptosis, which may explain some of its long-term benefits in mood disorder prevention.

Lithium is renally excreted and competes with sodium in the kidney. Conditions that reduce sodium (dehydration, low-salt diets, diuretics) cause the kidney to reabsorb more lithium, increasing levels and toxicity risk.

Side Effects

Common

• Fine hand tremor (most common; often dose-related)
• Polyuria and polydipsia (increased urination and thirst)
• Nausea, diarrhea, vomiting — often at the start of therapy
• Weight gain
• Cognitive dulling or mild memory impairment
• Acne and psoriasis exacerbation
• Hypothyroidism (occurs in up to 40% of long-term users)
• Edema

Serious

• Lithium toxicity — signs include coarse tremor, confusion, ataxia, seizures, cardiac arrhythmia; can be fatal
• Nephrogenic diabetes insipidus — impaired urinary concentration; occurs with long-term use
• Chronic kidney disease — long-term use associated with structural kidney changes; regular renal function monitoring is essential
• Cardiac conduction abnormalities — T-wave changes; rare arrhythmias
• Ebstein's anomaly — cardiac malformation risk if used in first trimester of pregnancy (risk is small but real)

Drug Interactions

Drug / Class	Interaction	Clinical Significance
NSAIDs (ibuprofen, naproxen, indomethacin)	Reduce renal lithium clearance by inhibiting prostaglandin-mediated effects on tubular function; increase lithium levels by 25–60%	High — avoid or use with extreme caution; use acetaminophen instead
Thiazide diuretics (hydrochlorothiazide)	Increase lithium reabsorption in the proximal tubule due to sodium depletion; can cause toxicity	High — avoid; if necessary, reduce lithium and monitor levels closely
ACE inhibitors / ARBs (lisinopril, losartan)	Reduce renal lithium excretion, raising levels significantly	High — combination requires careful monitoring; dose adjustment often needed
Haloperidol and antipsychotics	Rare reports of irreversible neurotoxicity; additive risk of QT prolongation	Moderate — monitor for neurological symptoms; combination is widely used but requires vigilance
SSRIs / SNRIs	Risk of serotonin syndrome with combination; lithium may enhance serotonergic effects	Moderate — generally used together safely but monitor for serotonergic symptoms
Caffeine	Increases renal lithium clearance; reducing caffeine intake may raise lithium levels	Low–Moderate — advise patients to maintain consistent caffeine intake
Sodium (dietary)	Low-sodium diet decreases renal lithium clearance, raising blood levels; high-sodium diet does the opposite	High — patients should maintain consistent salt intake and avoid dehydration

Warnings & Contraindications

Key Precautions

• Dehydration and fever: Even mild dehydration (illness, hot weather, exercise) can raise lithium levels to toxic range; patients must maintain adequate fluid and salt intake
• Renal monitoring: Serum creatinine and eGFR should be checked regularly; kidney function declines in some long-term users
• Thyroid monitoring: TSH should be checked at baseline and at least annually; hypothyroidism can be treated with levothyroxine without stopping lithium
• Pregnancy: Risk of Ebstein's anomaly in first trimester; careful risk-benefit discussion required; neonatal lithium toxicity risk at delivery
• Elderly patients: Reduced renal clearance increases toxicity risk; use with extra caution and close monitoring

Frequently Asked Questions

How often do lithium blood levels need to be checked?

Blood level monitoring is a core part of lithium therapy. Levels are typically checked frequently when starting or adjusting therapy to establish the correct range for the individual patient, then less often once stable — typically every 3 to 6 months for long-term users. Levels should also be checked any time symptoms of toxicity appear, after illness causing dehydration, or when other medications are changed.

What are the early signs of lithium toxicity?

Early signs include a coarser tremor than usual (the normal tremor is fine), nausea and diarrhea, drowsiness, confusion, slurred speech, and muscle twitching. If any of these appear, patients should stop lithium and seek medical attention immediately. Poison Control (1-800-222-1222) can also provide guidance. Toxicity is a medical emergency at its more severe stages.

Does lithium permanently damage the kidneys?

Long-term lithium use is associated with structural kidney changes and a modest decline in glomerular filtration rate in some patients. The risk of clinically significant chronic kidney disease increases with duration of use, higher blood levels, and episodes of acute toxicity. Regular monitoring allows early detection of kidney changes and informed treatment decisions. Many patients take lithium safely for decades without significant kidney problems.

Can lithium be used during pregnancy?

Lithium is classified as Category D due to a small but established risk of Ebstein's anomaly (a cardiac malformation) with first-trimester exposure. However, the absolute risk is low, and untreated bipolar disorder carries its own serious risks during pregnancy. The decision to continue or stop lithium during pregnancy should be made collaboratively between patient and clinician, with maternal-fetal medicine consultation as needed.