Lithium carbonate is a mood-stabilizing medication used primarily to treat bipolar disorder. It is approved for managing acute manic episodes and as a long-term maintenance therapy to reduce the frequency and intensity of future episodes. It remains one of the oldest and most effective psychiatric medications still in wide use, with additional off-label applications in treatment-resistant depression, vascular headaches, and suicide prevention.
Approved Uses for Bipolar Disorder
Lithium carbonate has two distinct approved roles. The first is treating active manic episodes, the periods of abnormally elevated mood, energy, and impulsive behavior that define the “highs” of bipolar disorder. The second is maintenance therapy: staying on lithium long-term to keep those episodes from returning or to make them less severe when they do occur. It is approved for patients aged 7 and older.
For many people with bipolar disorder, lithium is the foundation of their treatment plan. It works on both ends of the mood spectrum, though its anti-manic effects are more pronounced than its ability to prevent depressive episodes. Some people stay on lithium for decades.
Off-Label Uses
Doctors also prescribe lithium carbonate for conditions beyond its formal approval. As an add-on therapy for major depressive disorder, it can boost the effectiveness of antidepressants that aren’t working well enough on their own. It’s used for vascular headaches (including cluster headaches) and occasionally to treat low white blood cell counts, a condition called neutropenia. These off-label uses are generally reserved for situations where other treatments have failed.
One of lithium’s most studied secondary benefits is its association with reduced suicide risk. A systematic review and meta-analysis published in the BMJ found that lithium lowers the risk of suicide in people with mood disorders. This effect appears to be independent of its mood-stabilizing properties, though the exact reason isn’t fully understood.
How Lithium Works in the Brain
Lithium’s mechanism of action is unusually broad compared to most psychiatric medications, which is part of why scientists still debate exactly how it works. Rather than targeting a single receptor or neurotransmitter, it influences multiple systems simultaneously.
On the neurotransmitter level, lithium dials down dopamine activity, which likely explains its ability to calm manic symptoms. It also appears to boost serotonin signaling over time, primarily by acting on the part of the nerve cell that releases serotonin. Beyond neurotransmitters, lithium affects key signaling pathways inside cells. It blocks an enzyme called GSK-3 beta, which plays a role in how brain cells grow, develop, and form new connections. It also promotes the production of a protein that supports nerve cell health and survival, essentially encouraging the brain to maintain and repair its own wiring.
This combination of effects on mood-related brain chemicals, internal cell signaling, and long-term brain cell health helps explain why lithium works for both acute crises and long-term stability.
Common Side Effects
Lithium’s side effects range from mildly annoying to serious, depending on the dose and how long you’ve been taking it. The most common complaints are increased thirst and frequent urination, which affect up to 70% of long-term users. Hand tremor occurs in roughly one in four people on lithium. Nausea affects 10 to 20% of patients but tends to fade after the first weeks of treatment. Diarrhea develops in up to 10% of users over the first six months.
Most of these side effects are manageable and don’t require stopping the medication. They’re often worse early in treatment or after dose increases and settle down as your body adjusts.
Long-Term Effects on Kidneys and Thyroid
The two organs that need the most attention during long-term lithium use are the kidneys and the thyroid gland.
Lithium reduces the kidneys’ ability to concentrate urine by about 15% and can lower the filtration rate by up to 5 ml per minute per year. Research shows that long-term lithium users face roughly double the risk of developing moderate chronic kidney disease compared to the general population. Actual kidney failure requiring dialysis is rare but documented. The risk increases with duration of use, which is why regular kidney function tests are essential.
Thyroid problems are even more common. People on lithium have about six times the risk of developing clinical hypothyroidism, where the thyroid gland doesn’t produce enough hormone. In one study of 66 patients who had taken lithium for 10 to 44 years, 22% of the women showed features of hypothyroidism. The good news is that this is straightforward to manage with thyroid hormone replacement, and it doesn’t usually require stopping lithium.
The Therapeutic Window
Lithium has one of the narrowest therapeutic windows of any commonly prescribed medication, meaning the difference between an effective dose and a toxic one is small. This is why regular blood tests are non-negotiable.
For maintenance treatment in adults, the standard target blood level is 0.60 to 0.80 mmol/L. If you’re responding well but struggling with side effects, your doctor may aim for a lower range of 0.40 to 0.60 mmol/L. If you’re not responding adequately, the target can be raised to 0.80 to 1.00 mmol/L. During acute manic episodes, higher levels (typically 1.0 to 1.5 mEq/L) are used temporarily.
Before starting lithium, you’ll have baseline blood work done including kidney function, thyroid levels, blood cell counts, and a pregnancy test if applicable. Once you’re on a stable dose, expect blood draws every three to six months to check lithium levels, kidney function, and thyroid status.
Recognizing Lithium Toxicity
Because the margin between a therapeutic dose and a dangerous one is thin, knowing the warning signs of toxicity matters. Symptoms are grouped by severity:
- Mild toxicity (1.5 to 2.5 mEq/L): nausea, vomiting, worsening tremor, fatigue, and sluggishness
- Moderate toxicity (2.5 to 3.5 mEq/L): confusion, agitation, rapid heart rate, and muscle stiffness
- Severe toxicity (above 3.5 mEq/L): seizures, coma, dangerously low blood pressure, and high body temperature
Anything that shifts your body’s fluid or salt balance can push lithium levels up unexpectedly. Dehydration from illness, heavy sweating, or vomiting is a common trigger. If you develop a stomach bug or any illness that causes fluid loss, your lithium level can rise even without changing your dose.
Interactions With Food, Drinks, and Medications
Your lithium level is closely tied to how your kidneys handle sodium and water. Several common medications can raise lithium to dangerous levels by affecting kidney function. The most important ones to watch for are NSAIDs (ibuprofen, naproxen), ACE inhibitors and similar blood pressure medications, and thiazide diuretics. SSRIs can also increase lithium concentrations. If you’re prescribed any new medication, your lithium level should be rechecked.
Caffeine works in the opposite direction. It can lower lithium levels, which means a sudden change in your coffee habit (either drinking much more or quitting abruptly) can destabilize your blood level. The same goes for significant changes in salt intake. Eating much less salt than usual can cause lithium to accumulate, while a sudden increase in salty foods can lower it. Consistency matters more than the specific amount.
Available Forms and Dosing
Lithium carbonate comes in capsules (150 mg, 300 mg, and 600 mg) and as an oral solution. Extended-release tablets are also available. During acute manic episodes, a typical dose is 600 mg three times daily. For long-term maintenance, the dose is usually lower, often 300 mg three or four times a day, adjusted based on blood levels and how you respond. Dosing is always individualized, and finding the right amount takes time and repeated blood tests.