Lithium salts are chemical compounds formed when lithium, the lightest metal on the periodic table, bonds with other elements or molecules. In medicine, they are best known as one of the oldest and most effective treatments for bipolar disorder, used to stabilize mood and prevent manic episodes. The two most common forms are lithium carbonate (a white powder taken as tablets or capsules) and lithium citrate (a liquid formulation). Outside of psychiatry, lithium salts also appear in industrial applications like ceramics, glass, and battery manufacturing, but most people encounter the term in a medical context.
Common Types of Lithium Salts
Lithium carbonate is the most widely prescribed form. It has the chemical formula Li₂CO₃, a molecular weight of about 74 g/mol, and appears as a white crystalline powder. It earned its place as the standard formulation because it absorbs less moisture from the air than other lithium salts and causes less stomach irritation, particularly compared to lithium chloride.
Lithium citrate is the main alternative. It comes as a liquid solution, which makes it useful for people who have difficulty swallowing pills. A single teaspoon (5 mL) of lithium citrate liquid delivers the same amount of active lithium as a 300 mg lithium carbonate tablet. When researchers compared controlled-release versions of both formulations in a crossover study, total bioavailability was similar, though lithium citrate produced a slightly lower peak concentration in the blood.
Other lithium salts exist, including lithium chloride and lithium orotate (sold as a supplement), but lithium carbonate and lithium citrate are the only forms used in standard psychiatric treatment.
How Lithium Was Discovered as a Psychiatric Drug
Lithium’s psychiatric history stretches back further than most people realize. In 1871, William Hammond, a professor at Bellevue Hospital Medical College in New York, became the first physician to prescribe lithium for mania. His early work was largely forgotten. The modern era of lithium therapy began in 1949, when Australian psychiatrist John Cade, working at Bundoora Repatriation Hospital near Melbourne, tested lithium citrate and lithium carbonate on 10 manic patients. Cade had hypothesized that uric acid might play a role in psychotic excitement, and he chose lithium because of its known ability to dissolve uric acid (it had been used for gout decades earlier). The results were striking enough to eventually reshape psychiatric treatment worldwide.
What Lithium Does in the Brain
Lithium’s mechanism of action is unusually broad compared to most psychiatric medications. At the level of chemical signaling between brain cells, it influences three major neurotransmitter systems: dopamine, glutamate, and GABA. Dopamine drives motivation and reward-seeking behavior, glutamate is the brain’s primary excitatory signal, and GABA is its primary calming signal. By modulating all three, lithium can dampen the runaway excitation that characterizes mania without simply sedating the brain.
Deeper inside cells, lithium blocks several signaling proteins that regulate how neurons grow, communicate, and respond to stimulation. One of the most studied targets is an enzyme called GSK-3, which plays roles in cell survival, inflammation, and the internal clock that governs circadian rhythms. Lithium also inhibits enzymes involved in a signaling cascade that controls how strongly neurons respond to incoming messages. This combination of effects at multiple levels likely explains why lithium works as both an acute treatment for mania and a long-term mood stabilizer, something few other drugs accomplish.
Medical Uses
Lithium is FDA-approved for two specific purposes: treating acute manic episodes in bipolar disorder and preventing future episodes as ongoing maintenance therapy. It remains one of the few psychiatric medications with strong evidence for reducing suicide risk, which gives it a unique place in treatment guidelines even as newer mood stabilizers have entered the market.
For acute mania, the typical starting point is 600 mg of lithium carbonate taken two to three times daily. Once the episode stabilizes, the maintenance dose usually drops to 300 to 600 mg taken two to three times daily. Extended-release tablets use slightly different dosing schedules. The goal in all cases is to reach a specific concentration of lithium in the blood, which requires regular blood draws to verify.
The Narrow Therapeutic Window
One of the most important things to understand about lithium salts is how thin the line is between a therapeutic dose and a toxic one. The target blood level for treatment sits between 0.6 and 1.2 mEq/L. Levels above 1.5 mEq/L can signal toxicity in people on long-term therapy, and levels above 2.0 mEq/L are considered outright dangerous. That gap between “effective” and “toxic” is remarkably small, which is why lithium requires closer monitoring than most psychiatric medications.
Blood lithium levels can shift based on hydration, kidney function, salt intake, and interactions with other medications. Something as simple as becoming dehydrated on a hot day or starting a new blood pressure medication can push levels into a risky range. This is not a reason to avoid lithium, but it is the reason treatment involves routine blood work rather than simply refilling a prescription.
Effects on the Thyroid and Kidneys
Lithium’s two most significant long-term concerns involve the thyroid gland and the kidneys. Both are well documented and manageable with proper monitoring, but they’re worth understanding if you or someone you know takes lithium.
Thyroid effects were first noticed in the late 1960s, when goiters appeared in a group of lithium-treated patients. Lithium interferes with the thyroid gland in several ways: it blocks the release of thyroid hormones, may reduce iodine uptake, and can inhibit hormone production. The result, in some patients, is an underactive thyroid. This is typically treated by adding a thyroid hormone supplement alongside lithium rather than stopping lithium itself.
Kidney effects stem from lithium’s interference with how the kidneys respond to the hormone that tells them to conserve water. Normally, this hormone signals the kidneys to concentrate urine and hold onto fluid. Lithium disrupts that signal, leading to dilute urine and increased thirst. Early in treatment, this effect is reversible, similar to the way alcohol temporarily increases urination. Over years, however, the changes can become structural and permanent in some patients. This is why kidney function tests are a standard part of long-term lithium monitoring.
Other Side Effects
Beyond thyroid and kidney concerns, lithium commonly causes a fine hand tremor, mild nausea (especially when starting treatment), increased thirst, and weight gain. Many of these side effects are dose-related, meaning they improve when blood levels sit at the lower end of the therapeutic range. The tremor tends to be most noticeable during tasks that require fine motor control, like writing or threading a needle, and often becomes less pronounced over time.
Stomach-related side effects are generally milder with lithium carbonate than with other lithium salts, and taking the medication with food can reduce nausea further. Extended-release formulations also help by spreading absorption over a longer period, which avoids the sharp spike in blood levels that immediate-release tablets produce.
Lithium Salts Outside of Medicine
While the medical use dominates most conversations, lithium salts have a wide industrial footprint. Lithium carbonate is a key ingredient in lithium-ion batteries, which power everything from smartphones to electric vehicles. It’s also used in ceramics and glass production, where it lowers melting temperatures and improves durability. Lithium chloride serves as a desiccant in industrial drying systems because of its strong ability to absorb moisture. Lithium stearate is used as a thickener in high-performance greases. The same element that stabilizes mood in the brain stabilizes chemical reactions in factories, though the concentrations and contexts are entirely different.