Lithium is the oldest mood stabiliser still in regular use. Discovered to calm mania in 1949 by John Cade, it has retained a central place in bipolar disorder treatment ever since. In schizophrenia care, however, its role is narrower and more debated. It is not a primary treatment for schizophrenia, but as an augmenting agent it still has a defensible place — especially in schizoaffective disorder, in patients with persistent mood symptoms, and in those with severe aggression or suicidality.
Lithium is a mood-stabilising element that, when added to an antipsychotic, may help schizophrenia patients with prominent mood symptoms, aggression, or suicidal thinking — but it does not reliably improve core psychotic symptoms on its own.
What lithium is and how it works
Lithium is a naturally occurring element. Its mechanism in psychiatric illness remains imperfectly understood despite decades of research, but it is known to affect inositol monophosphatase, glycogen synthase kinase-3 (GSK-3), and a range of intracellular signalling pathways. Clinically, it stabilises mood, reduces the frequency and severity of manic episodes, and has the strongest evidence of any psychiatric medication for reducing suicide.
Why it is sometimes added in schizophrenia
The strongest evidence base for lithium augmentation in schizophrenia covers the following situations:
- Schizoaffective disorder, especially the bipolar subtype — see schizoaffective disorder explained
- Persistent mood instability alongside antipsychotic-treated psychosis
- Severe persistent aggression not responsive to antipsychotic adjustment
- Persistent suicidal thinking in patients with schizophrenia or schizoaffective disorder
For purely positive psychotic symptoms in classic schizophrenia, lithium is not first-line. Cochrane reviews of lithium for schizophrenia have found that the evidence for added benefit on psychotic symptoms specifically is weak. Most experienced clinicians use it for the indications above, not as a generic add-on.
Typical dosing and monitoring
Lithium is unusual among psychiatric medications because dosing is driven by blood levels, not by weight or symptom severity alone. Therapeutic levels for augmentation are typically 0.6 to 0.8 mEq/L for maintenance and 0.8 to 1.0 mEq/L during acute episodes. Levels above 1.2 mEq/L start to be in the toxicity range.
This narrow therapeutic window is the main reason lithium requires careful monitoring:
- Blood level checks — initially weekly, then monthly, then every 3 to 6 months once stable
- Kidney function (creatinine, eGFR) — every 3 to 6 months
- Thyroid function (TSH) — annually or more often
- Calcium — checked periodically
- Pregnancy testing in patients of childbearing potential before starting
Side effects
Even at therapeutic levels, lithium has notable side effects:
- Tremor — fine hand tremor is common
- Increased thirst and urination — sometimes substantial
- Weight gain — modest in most
- Acne and worsened psoriasis
- Hypothyroidism — relatively common, easily managed with levothyroxine
- Cognitive flattening — sometimes reported as feeling "dulled"
- Diarrhoea or nausea
- Long-term: kidney function decline in some patients, particularly with decades of use or repeated toxicity
The danger of toxicity
Coarse tremor, severe nausea or vomiting, diarrhoea, slurred speech, confusion, ataxia (unsteady walking), muscle twitching, or seizures. These can be signs of lithium toxicity, which is a medical emergency.
Lithium toxicity can occur with relatively small dose increases, dehydration (illness, hot weather, exercise), low-sodium diet, or interactions with NSAIDs (ibuprofen), ACE inhibitors, and certain diuretics. Anyone on lithium should keep this in mind during any new illness, surgery, or medication change.
Pregnancy considerations
Lithium has been associated with a small increased risk of fetal cardiac malformations, particularly Ebstein's anomaly. The absolute risk is small (estimates around 1 in 1,000 to 1 in 2,000 versus 1 in 20,000 in the general population), and lithium is sometimes continued in pregnancy when the risk of relapse is high. This is a complex decision that belongs in a focused conversation with a psychiatrist familiar with perinatal care.
Drug interactions to know
- NSAIDs (ibuprofen, naproxen) — raise lithium levels
- ACE inhibitors and ARBs — raise lithium levels
- Thiazide diuretics — raise lithium levels
- Caffeine — lowers lithium levels
- Acetaminophen (paracetamol) — generally safe
- Significant changes in salt or fluid intake — affect lithium levels
The suicide reduction question
One of the most consistent findings in psychiatric pharmacology is that lithium reduces suicide. This effect appears to be at least partly independent of its mood-stabilising properties. For patients with schizoaffective or schizophrenia who have a history of repeated suicide attempts or persistent suicidal thinking, this is one of the strongest reasons to consider lithium, even when mood symptoms are not the leading problem.
Who probably should not take lithium
- People with significantly reduced kidney function
- People who cannot reliably maintain hydration
- People who cannot attend the required blood monitoring
- People with unstable cardiac conditions
- People in the first trimester of pregnancy, where alternatives exist
Practical questions for your prescriber
- What specific symptoms are we hoping lithium will address?
- What is the target blood level, and how will we monitor?
- What should I do if I get sick or dehydrated?
- What over-the-counter medications should I avoid?
- How long is a fair trial before deciding it isn't helping?
This article is for educational purposes only and is not medical advice, diagnosis, or treatment. Always consult a qualified mental health professional. If you or someone you know is in crisis, call or text 988 in the US, or your local emergency number.