Lithium has shown meaningful effects on some of the most disruptive symptoms of borderline personality disorder, particularly impulsivity, aggression, mood swings, and self-harm, yet it remains one of the least prescribed medications for the condition. A systematic review of nine studies found lithium useful for reducing emotional and impulsive behaviors, stabilizing mood, and curbing suicidal tendencies in people with BPD. Despite that evidence, only about 4% of hospitalized BPD patients actually receive it. The gap between what the research suggests and what happens in clinical practice is wide, and the reasons behind it are worth understanding.
Which BPD Symptoms Lithium Addresses
BPD is defined by a cluster of problems: emotional instability, impulsive behavior, unstable relationships, chronic feelings of emptiness, and recurrent self-harm or suicidal behavior. Lithium does not treat BPD as a whole. No medication does. But research consistently points to a few symptom domains where it helps. A systematic review covering nine studies found it effective at reducing emotional and impulsive behaviors, stabilizing mood, and lowering suicidal tendencies, outperforming placebo in preventing recurrence of mood disturbance.1PubMed Central. The effect of LITHIUM in mood improvement in patient with borderline personality disorder; A systematic review A narrative review reached similar conclusions, noting lithium’s capacity to reduce impulsivity, aggression, suicidal tendencies, and self-harm in BPD specifically.2Current Problems of Psychiatry. The meaning of lithium and naltrexone pharmacotherapy in the treatment of borderline personality disorder – a narrative review
The mood-swing component of BPD deserves special attention here. People with BPD experience rapid shifts in emotional state, sometimes within hours, that differ from the longer-cycle mood episodes seen in bipolar disorder. Early pharmacotherapy research recognized that this particular pattern of mood instability responds to lithium.3PubMed. Pharmacotherapy for personality disorders That finding matters because not every mood stabilizer targets the same kind of instability. Lithium’s effect on rapid, reactive mood shifts is part of what makes it relevant to BPD rather than just borrowed from bipolar treatment.
The anti-aggressive effects extend beyond BPD. Multiple studies, mostly open trials, have demonstrated lithium’s capacity to dampen impulsive aggression across a range of diagnoses including personality disorders, schizophrenia, and unipolar depression.4Brazilian Journal of Psychiatry. Pharmacological treatment of impulsivity and aggressive behavior That breadth suggests lithium acts on a transdiagnostic mechanism rather than being condition-specific, which helps explain why it can benefit BPD patients even though it was never developed with their diagnosis in mind.
Why So Few People with BPD Actually Receive Lithium
If lithium works on core BPD symptoms, you might expect it to be commonly prescribed. It is not. In a study of over 2,000 hospitalized BPD patients, only 4% received lithium. By comparison, 70% were on antipsychotics or antidepressants, 33% received anticonvulsants, and 30% were given benzodiazepines.5European Neuropsychopharmacology. Psychopharmacological treatment of 2195 in-patients with borderline personality disorder: A comparison with other psychiatric disorders That 4% figure is striking given the evidence for lithium’s effects on impulsivity and mood instability.
Several forces push clinicians away from lithium for BPD. First, the evidence base, while positive in direction, is thin. Most of the supporting studies are small or open-label. Clinical guidelines reflect that uncertainty: a systematic review of BPD treatment guidelines found that while all of them acknowledged a potential role for medication, the nature and extent of that role is disputed.6PubMed Central. Clinical practice guidelines for the treatment of borderline personality disorder: a systematic review of best practice in anticipation of MAiD MD-SUMC Without strong guideline endorsement, many prescribers default to drugs they feel more comfortable with.
Second, lithium requires regular blood monitoring and has a narrow therapeutic window, meaning the difference between an effective dose and a toxic one is relatively small. That creates practical challenges for any patient but raises particular concerns with BPD, a condition where treatment adherence can be inconsistent and self-harm risk is elevated. Third, the culture of BPD treatment has long favored psychotherapy, particularly dialectical behavior therapy, as the primary intervention, with medication seen as an adjunct at best. That framing tends to push medication decisions toward drugs perceived as safer or easier to manage, even when their evidence for BPD is no stronger than lithium’s.
The Bipolar Misdiagnosis Problem
Understanding lithium’s relationship to BPD also means understanding how frequently BPD is confused with bipolar disorder. The two conditions share surface-level features: mood instability, impulsivity, relationship difficulties. But the underlying patterns differ substantially. In BPD, mood shifts tend to be rapid, reactive to interpersonal events, and short-lived. In bipolar disorder, episodes are typically longer, more autonomous, and follow a cyclical pattern.
That overlap leads to frequent misdiagnosis. In one study, nearly 40% of patients with BPD reported having previously been misdiagnosed with bipolar disorder, compared to about 10% of psychiatric patients without BPD. Patients who reported prior misdiagnosis were five times more likely to have BPD than those who had not been misdiagnosed.7Journal of Psychiatric Research. Borderline Personality Disorder and the Misdiagnosis of Bipolar Disorder This matters for the lithium question in two ways. Some BPD patients end up on lithium because they were initially diagnosed with bipolar disorder and started on a standard bipolar medication regimen. When the lithium helps, it may be because it is addressing BPD symptoms that were attributed to bipolar. Conversely, some patients who would benefit from lithium never receive it because their BPD diagnosis steers clinicians away from mood stabilizers altogether.
The misdiagnosis also complicates the research literature. Studies on lithium’s effectiveness in bipolar disorder may include patients who actually have BPD, muddying both sets of findings. And BPD studies may exclude patients who also carry a bipolar diagnosis, even if that diagnosis was wrong. The blurry diagnostic boundary between the two conditions has made it harder, not easier, to study lithium’s effects on BPD in isolation.
How Lithium Acts on the Brain
Lithium’s mechanism of action is famously hard to pin down. The most studied explanation involves an enzyme called glycogen synthase kinase 3, or GSK3, which lithium inhibits. GSK3 is a central hub in the brain, involved in dopamine and glutamate signaling, synaptic plasticity, inflammation, circadian rhythm regulation, protein synthesis, metabolism, and mitochondrial function.8PubMed Central. Inhibition of glycogen synthase kinase 3 by lithium, a mechanism in search of specificity That list is so broad that identifying which downstream effects are responsible for lithium’s clinical benefits remains a challenge. The enzyme has over 100 known substrates, meaning it touches an enormous number of biological processes. This breadth is part of why lithium has effects across mood disorders, aggression, suicidality, and impulsivity, and also why researchers have struggled to explain its benefits with a single, tidy mechanism.
For BPD specifically, the anti-impulsive and mood-stabilizing effects likely involve several of these pathways acting together. Serotonin dysfunction plays a role in BPD-related impulsivity, and lithium is known to influence serotonergic transmission. The anti-inflammatory effects of GSK3 inhibition may also matter, given emerging evidence linking neuroinflammation to emotional dysregulation. But the honest answer is that the field has not yet mapped the mechanism in BPD with the same precision it has attempted in bipolar disorder. The clinical findings are ahead of the mechanistic understanding.
Safety Concerns and Monitoring Requirements
Lithium is not a casual medication. It requires regular blood draws to check serum levels, because too much lithium in the bloodstream becomes toxic, causing tremor, nausea, confusion, and in severe cases, kidney failure or death. Adequate monitoring is essential for optimal dosing and for catching problems early.9PubMed Central. Monitoring of patients treated with lithium for bipolar disorder: an international survey
Long-term use carries two well-documented risks. A large study comparing lithium to other psychiatric medications found that lithium roughly doubled the risk of hypothyroidism and modestly increased the risk of moderate kidney disease. Higher serum levels correlated with greater risk for both thyroid problems and kidney decline, and repeated episodes of lithium toxicity further raised the kidney disease risk.10PubMed Central. Lithium for Bipolar Disorder and Risk of Thyroid Dysfunction and Chronic Kidney Disease The reassuring finding was that lithium did not increase the risk of the most severe kidney outcomes. But the thyroid and kidney monitoring burden is real and lifelong.
These risks take on added weight in BPD. One study of BPD inpatients found that the vast majority were prescribed at least one psychotropic medication, with about a third taking three or more different agents. Over a third of all prescribed psychotropics were for off-label indications, and the most common drugs taken in overdose were the ones that had been prescribed to the patient.11PubMed Central. Overdose and off-label psychotropic prescribing in patients with borderline personality disorder: A retrospective series Severe toxicity occurred in about one in six overdose presentations. Lithium’s narrow safety margin makes it a legitimate concern in a population with elevated overdose risk, and this is a factor clinicians weigh heavily.
That said, the overdose concern needs perspective. The most commonly overdosed drug classes in that study were benzodiazepines and antipsychotics, not mood stabilizers. Benzodiazepines are prescribed to about 30% of hospitalized BPD patients, despite their own risks. The point is not that lithium is safe by comparison, but that the overdose argument against lithium should be applied consistently across all medications prescribed to this population, and often it is not.
How Lithium Compares to Other Mood Stabilizers for BPD
When clinicians do reach for a mood stabilizer in BPD, lithium is rarely the first choice. Anticonvulsants like valproate and lamotrigine are prescribed more often, partly because they do not require the same blood-level monitoring. But the evidence for these alternatives is not necessarily stronger. A review of valproate’s psychiatric applications concluded that while it has been used in BPD, the data are insufficient to recommend it.12Taylor & Francis Online. A review of valproate in psychiatric practice A broader review noted that various mood stabilizers including lithium, carbamazepine, valproate, and lamotrigine have been studied in BPD, but findings related to mood stabilizers other than lithium were characterized as inadequate.13PubMed Central. Borderline personality disorder: bipolarity, mood stabilizers and atypical antipsychotics in treatment
Lamotrigine has attracted interest for BPD-related affective symptoms and has a gentler side-effect profile than lithium, which makes it appealing in practice. But the comparative evidence, as in head-to-head trials showing one is better than the other for BPD, is essentially absent. What exists is a collection of small studies for each drug, none of them definitive, and clinicians choosing among them based on side-effect profiles, monitoring burden, and clinical intuition rather than clear superiority data.
Atypical antipsychotics like olanzapine, quetiapine, and risperidone are also used, and some have BPD-specific trial data. But they carry their own concerns, including metabolic syndrome, weight gain, and sedation. The honest picture is that no medication has strong enough evidence in BPD to be considered a clear first-line pharmacological treatment. Lithium’s evidence is as good as any individual alternative, and possibly better for impulsivity and self-harm, yet it gets used far less. The monitoring burden and overdose risk largely explain the gap.
The Low-Dose Approach
One emerging thread in the literature tries to thread the needle between lithium’s benefits and its risks by using lower doses than those standard in bipolar disorder. A recent case report documented complete remission of impulsive self-harming behaviors and affective instability in a BPD patient treated with low-dose lithium as a single medication.14PubMed. Low-Dose Lithium Monotherapy in Borderline Personality Disorder: Complete Remission of Impulsive Self-Harming Behaviors and Affective Instability A single case report is not proof, but it aligns with a broader hypothesis: BPD-related mood instability and impulsivity might respond to lithium levels lower than those needed for bipolar mania prevention.
If that turns out to be true, it would change the risk-benefit calculation substantially. Lower doses mean lower serum levels, which the kidney and thyroid data suggest would reduce long-term organ damage. They would also widen the gap between the therapeutic dose and a toxic overdose, partially addressing the safety concern in a high-risk population. The monitoring burden would not disappear, but it might become less onerous. This is speculative at the moment, based on very early data, but it represents the direction some researchers are pushing.
Polypharmacy and the Medication Load Problem
Most people with BPD who receive medication are not on just one drug. The average hospitalized BPD patient in one large study was taking nearly three different psychotropic medications simultaneously, and over half were on three or more.15European Neuropsychopharmacology. Psychopharmacological treatment of 2195 in-patients with borderline personality disorder: A comparison with other psychiatric disorders That level of polypharmacy is concerning for anyone, but it is especially problematic when you add a drug like lithium that interacts with common medications (anti-inflammatory drugs, certain blood pressure medications, and some antidepressants can all raise lithium levels) and where accumulation can quickly become dangerous.
This creates a practical question: if you are already on two or three medications for BPD-related symptoms, is adding lithium worth the increased complexity? In some cases, lithium might work well enough to replace one or more existing drugs, simplifying the regimen rather than adding to it. The case report on low-dose lithium monotherapy gestures at exactly that possibility. But in practice, adding rather than replacing is the more common pattern in psychiatric prescribing, and the result is medication stacks that nobody has studied in combination for BPD.
The broader issue is that medication use in BPD has gotten ahead of the evidence. Over a third of psychotropics prescribed to BPD patients are off-label, meaning they are being used for indications that lack regulatory approval and sometimes lack strong trial data.16PubMed Central. Overdose and off-label psychotropic prescribing in patients with borderline personality disorder: A retrospective series Lithium for BPD would be off-label too. But unlike many off-label prescriptions that have accumulated quietly without formal study, lithium at least has a small body of positive evidence specifically in BPD, which puts it ahead of some medications that get prescribed more freely.
Why the Evidence Base Remains Thin
Researchers have called for rebuilding the evidence on lithium for BPD, and that phrasing is telling. It implies something was there before and eroded. What happened is that early studies from the 1970s and 1980s showed promising results, but the field moved on. Psychotherapy became the dominant treatment paradigm for BPD, and pharmaceutical industry interest in funding trials gravitated toward newer, patented drugs rather than lithium, which has been available as a generic for decades. No company stands to profit from demonstrating that a cheap, unpatentable salt works for BPD, so the large randomized controlled trials that would settle the question have never been funded.
The result is an evidence base composed mostly of small studies and open-label trials, the kind of data that produces suggestive but not conclusive findings. Systematic reviews can pool those studies and find consistent directions of effect, as the nine-study review did when it concluded lithium helps with mood and impulsivity in BPD.17PubMed Central. The effect of LITHIUM in mood improvement in patient with borderline personality disorder; A systematic review But they cannot make weak studies into strong ones. Until someone runs adequately powered randomized trials, the evidence will remain a suggestive picture rather than a definitive one, and guidelines will continue to hedge.
This is frustrating for patients and clinicians alike, because the clinical reality is that medications are being prescribed for BPD regardless of the evidence gaps. The question is not whether BPD patients will take psychiatric drugs; nine out of ten hospitalized BPD patients already do. The question is whether those drugs will be chosen based on the best available evidence or on habit and convenience. By that standard, lithium’s 4% prescription rate looks less like appropriate caution and more like an evidence-practice gap running in the wrong direction.
What Lithium Cannot Do for BPD
Lithium addresses some BPD symptoms but leaves others largely untouched. The chronic emptiness, identity disturbance, and unstable relationship patterns that define BPD are not mood symptoms in the conventional sense, and there is no reason to expect a mood stabilizer to resolve them. These features are better addressed through psychotherapy, particularly approaches like dialectical behavior therapy and mentalization-based therapy that directly target relational and identity patterns.
The framing matters here. If a patient or clinician approaches lithium hoping it will “treat BPD,” disappointment is likely. If they approach it as a targeted intervention for specific symptom domains, particularly impulsive self-harm and rapid mood shifts, the expectations are more realistic and the outcomes may be genuinely useful. BPD is not a single problem with a single solution. It is a cluster of related difficulties, and medication at its best addresses a subset of those difficulties well enough to make the therapy that handles the rest more effective. Lithium fits that supporting role for the right patient, but it is not, and probably will never be, a standalone treatment for BPD.