Lithium: what it treats, how to take it, side effects
Last updated September 3, 2026.
Lithium is the original mood stabilizer - an antimanic agent that decreases abnormal activity in the brain. It has treated bipolar disorder longer than any other drug in its class, and it works with a narrow margin: the dose that helps sits close to the dose that harms, which is why blood tests are part of the medicine.
What does it treat?
Episodes of mania - the frenzied, abnormally excited mood - in people with bipolar disorder, and prevention of future episodes. Doctors also sometimes use it for depression, schizophrenia, and impulse-control disorders. It controls the condition; it does not cure it, and full benefit can take 1 to 3 weeks or longer.
How do you take it?
Tablets, capsules, or liquid three to four times a day; extended-release tablets two to three times a day, swallowed whole - same times every day. The label's boxed warning explains the rhythm: lithium toxicity is closely related to blood lithium levels and can occur at doses close to therapeutic ones, so your doctor orders regular blood tests and you keep every single one. Steady fluid and steady salt intake are the other half of dosing - your doctor gives specific diet directions, and they are part of the prescription. Missed dose: take it when you remember unless the next one is close; never double up.
Side effects to know
- Common: restlessness, a fine hand tremor, mild thirst, loss of appetite, stomach discomfort or gas, weight changes, dry mouth or extra saliva, acne, hair changes, and feeling the cold more than usual.
- Serious - call your doctor immediately or get emergency help: excessive thirst, frequent urination, slow jerky or uncontrollable movements, blackouts, seizures, fainting, irregular or pounding heartbeat, shortness of breath, chest tightness, confusion, hallucinations, crossed eyes, cold discolored fingers or toes, or swelling of the feet and ankles.
- Toxicity signs - stop lithium and call immediately: drowsiness, shaking you cannot control, muscle weakness or twitching, loss of coordination, diarrhea, vomiting, slurred speech, giddiness, ringing in the ears, or blurred vision.
Who should not take it?
People with significant kidney or heart disease, severe dehydration, or sodium depletion - the label says lithium should generally not be given in these situations. Diuretics (water pills) are a direct conflict; common pain relievers are too - ibuprofen, naproxen, and other NSAIDs raise lithium levels, as does sodium bicarbonate, so none of them start without your doctor. Tell your doctor about thyroid disease, unexplained fainting, or family history of Brugada syndrome or sudden death before 45. The toxicity accelerants are everyday events: severe diarrhea, vomiting, excessive sweating, or fever all concentrate lithium - call your doctor when they happen. Caffeine habits go on the discussion list. Lithium can harm a fetus - if you become pregnant, call your doctor immediately. And it causes drowsiness: no driving until you know how it affects you.
When is it an emergency?
Seizures, fainting, blackouts, severe confusion, or an irregular pounding heartbeat is a 911 call - lithium toxicity moves fast once it moves. The stop-and-call list above is the earlier catch. For an overdose, call Poison Control at 1-800-222-1222. Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper.
What a Pymander AI doctor consult looks like
Illustrative example, not a real member's messages.
Common questions
Why does lithium need blood tests when my other meds don't?
The label's boxed warning is the answer: lithium toxicity is closely related to the level in your blood, and toxicity can occur at doses close to the therapeutic ones - the helpful dose and the harmful dose are neighbors. The blood draw is how your doctor keeps you on the right side of that line. Skipping the test is skipping the safety system, not just an appointment.
Why can't I take ibuprofen while on lithium?
NSAIDs - ibuprofen, naproxen, and their relatives - make the kidneys hold onto lithium, which pushes your blood level toward the toxic zone. MedlinePlus names them directly, along with sodium bicarbonate, and says not to start them while taking lithium without discussing with your doctor first. Your prescriber can tell you what to reach for instead when something hurts.
Why does my doctor care about salt and water on lithium?
Because your kidneys treat lithium and sodium like cousins. Sweat heavily, get dehydrated, cut your salt, or catch a stomach bug, and your lithium level climbs - MedlinePlus flags severe diarrhea, excessive sweating, and fever as call-the-doctor events. Steady fluid, steady salt, every day, is genuinely part of the dose.
What does lithium toxicity actually feel like?
The stop-taking-and-call list from MedlinePlus: drowsiness, shaking you cannot control, muscle weakness or twitching, loss of coordination, diarrhea, vomiting, slurred speech, giddiness, ringing in the ears, blurred vision. Notice the pattern - it looks like being very drunk, and it arrives through the everyday routes: dehydration, illness, a new pain reliever. Seizures, blackouts, and severe confusion are the 911 version.
Can I drink alcohol while taking lithium?
Neither the label nor MedlinePlus gives lithium-specific alcohol language - but alcohol dehydrates, and dehydration is one of the fastest routes to lithium toxicity. If you drink, that trade-off belongs in a real conversation with your prescriber, not a guess.
What happens if I miss a dose of lithium?
Take it as soon as you remember, unless it is almost time for the next one - then skip it and never double up. Doubling is the dangerous direction with this drug - a spike in level is the thing the whole monitoring system exists to prevent. One missed dose is far safer than one doubled dose.