Lithium

Key facts

• Lithium is a mood stabilizer used to treat manic episodes in bipolar disorder and, long-term, to prevent future manic and depressive episodes; it is also added to antidepressants for depression that has not responded to those medicines alone.
• It is taken as tablets or capsules, usually once or twice daily. Full mood-stabilizing benefit builds over days to weeks, not hours.
• Lithium has a narrow therapeutic index: the dose that helps and the dose that harms are close together. Regular blood tests to check your lithium level, plus kidney and thyroid function tests, are mandatory for as long as you take it.
• Seek urgent care for worsening tremor, confusion, persistent vomiting, or unsteady walking. These can be signs of lithium toxicity.

What lithium treats

Lithium treats bipolar disorder: the manic phase, with its elevated mood, racing thoughts and risky behavior, and, taken long-term, it prevents future manic and depressive episodes. It is also used alongside antidepressants when depression has not improved with those medicines alone. It does not relieve everyday stress or ordinary mood swings, and it is not a fast-acting sedative.

How lithium works

The exact mechanism is not fully understood, but lithium is thought to alter sodium movement in nerve cells and to change signaling pathways inside brain cells that regulate mood. This gradual action on brain chemistry is why lithium stabilizes mood over weeks rather than providing immediate relief.

Before you take it

• Tell your prescriber about kidney disease, thyroid disorders, heart disease, or if you are pregnant, planning a pregnancy, or breastfeeding. Lithium passes through the kidneys and thyroid and can harm a developing baby.
• Dehydration pushes lithium levels toward toxic. Vomiting, diarrhea, heavy sweating, heatwaves, or a sudden low-salt diet can all raise your level quickly.
• NSAID painkillers (ibuprofen, diclofenac) and some diuretics (thiazides) reduce how the kidneys clear lithium and can trigger toxicity. Tell every doctor and pharmacist that you take lithium before starting any new medicine.
• Regular blood tests to measure your lithium level are required, more often when starting or changing dose, along with periodic kidney and thyroid checks.

Side effects

Common effects, especially when starting: mild hand tremor, increased thirst and urination, nausea, and slight weight gain.

Stop and seek urgent medical care for any of these:

• Worsening tremor, muscle twitching, or loss of coordination.
• Confusion, extreme drowsiness, or slurred speech.
• Persistent vomiting or diarrhea.
• Blurred vision or ringing in the ears.

Safety essentials

• Lithium's narrow therapeutic index means the difference between an effective dose and a toxic one is small. Never change your dose on your own, and keep every scheduled blood test, missed tests let toxicity build undetected.
• Stay consistently hydrated and keep your salt intake steady. Sudden changes in fluid or salt intake swing your lithium level.
• Tell any doctor prescribing you something new, including over-the-counter painkillers, that you take lithium, since common drugs can raise your level into the toxic range.

This page is educational and does not replace advice from a doctor or pharmacist who knows your health history.