Does Lithium Affect Libido and Sexual Function?

Lithium can and does affect sexual function, including libido, arousal, and orgasm. In one study of clinically stable patients on lithium, roughly a third reported sexual dysfunction severe enough to be measured on a standardized scale. The picture is more complicated than a blanket warning, though, because the size of the effect depends heavily on what other medications a person takes alongside lithium, and the biological mechanisms behind the problem are still not fully mapped out.

How Common Is the Problem?

The best-cited estimate comes from a study of 100 clinically stable patients with bipolar disorder who were taking lithium. About a third of them met the threshold for sexual dysfunction on the Arizona Sexual Experience Scale, a brief questionnaire that covers desire, arousal, erection or vaginal lubrication, ability to reach orgasm, and satisfaction with orgasm.¹ That number applies to lithium whether it was taken alone or alongside other psychiatric medications, and the same study found that sexual dysfunction was strongly linked to poor medication adherence. People who had these side effects were more likely to skip doses or stop treatment altogether.

An older study painted a more reassuring picture when lithium was used on its own. In that sample, only about 14% of patients on lithium monotherapy reported difficulties with sexual functioning.² The gap between 14% and 37% is large, and a big part of the explanation likely comes down to what else those patients were taking, a point worth its own discussion below. Either way, the problem is real but not inevitable. Most people on lithium retain normal or near-normal sexual function.

What Lithium Does to Erectile and Arousal Tissue

The exact pathways through which lithium disrupts sexual function are still being worked out, but researchers have described both central nervous system effects and direct effects on the tissues involved in arousal. The review literature describes both “central and peripheral mechanisms” contributing to the problem, without a single dominant explanation.³

The most detailed lab work has focused on nitric oxide, the molecule that signals blood vessels in erectile tissue to relax and fill with blood. In rat studies, lithium reduced the ability of the corpus cavernosum to relax in response to acetylcholine, a chemical messenger that triggers nitric-oxide release from blood vessel walls. When researchers added the amino acid L-arginine, which the body uses to make nitric oxide, the tissue’s ability to relax partially recovered.⁴ Similar results appeared in guinea pig tissue, where lithium impaired the blood-vessel-wall-driven relaxation in a dose-dependent way but left nerve-driven relaxation intact.⁵

A chronic dosing study in rats confirmed these findings in a more realistic exposure scenario. After weeks of lithium administration, the erectile tissue showed significantly weaker relaxation responses compared to untreated controls. Interestingly, the tissue from lithium-treated rats actually showed increased activity of the enzyme responsible for making nitric oxide, possibly a compensatory response to the drug’s interference with normal signaling.⁶ In all of these studies, when the tissue was exposed to a direct nitric oxide donor that bypassed the natural signaling chain, both lithium-treated and control tissue relaxed equally well. That strongly suggests lithium disrupts the production or release of nitric oxide rather than damaging the muscle that responds to it.

Hormonal Effects

Beyond its direct effects on blood vessel signaling, lithium also appears to shift several hormones that matter for sexual desire and performance. Preclinical evidence suggests lithium can reduce testosterone levels and impair nitric-oxide-mediated relaxation of erectile tissue.⁷ A review of the available evidence found that lithium tends to increase prolactin and luteinizing hormone while decreasing testosterone, although that conclusion rests on relatively few studies.⁸ Elevated prolactin is well known to dampen libido in both sexes, so even a modest rise could contribute to the problem.

A recent cohort study measuring lithium exposure in the general environment added an unexpected wrinkle. Even at low environmental levels, lithium exposure was associated with decreased serum testosterone and progesterone in men, and animal experiments within the same study showed that higher doses damaged the Leydig cells responsible for producing testosterone.⁹ Therapeutic doses of lithium are higher than environmental exposure levels, so the hormonal effect in patients is likely at least as large and possibly more pronounced. The same study found reduced sperm motility and concentration in the highest-dose animal group, raising fertility concerns alongside the sexual function ones.

The Thyroid Connection

Lithium is well known to affect thyroid function, and an underactive thyroid is itself a cause of low libido, fatigue, and difficulty with arousal. A selective review of the endocrine and metabolic effects of psychiatric drugs noted that clinical hypothyroidism may be associated with lithium use and can be managed with thyroid hormone replacement.¹⁰ This matters practically because thyroid problems are treatable. If you develop sexual side effects on lithium, a thyroid panel is one of the first things worth checking. If your thyroid is being suppressed, correcting that with levothyroxine may improve sexual symptoms without requiring any change to your lithium dose.

Lithium Alone vs. Lithium Plus Other Drugs

One of the most important and underappreciated findings in this area is how much worse sexual dysfunction becomes when lithium is combined with other medications. In the study that measured sexual function across different prescribing patterns, patients on lithium alone had a 14% rate of sexual difficulties. When lithium was combined with benzodiazepines, that figure jumped to 49%. And no relationship was found between serum lithium levels or prolactin levels and sexual dysfunction scores, which means the problem was not simply a matter of the lithium dose being too high.²

This is a genuinely useful finding for patients. Many people with bipolar disorder take lithium alongside antidepressants, antipsychotics, or anti-anxiety medications, all of which carry their own sexual side effects. If sexual dysfunction develops while you are on a multi-drug regimen, the lithium may not be the main culprit. Working with a prescriber to identify which medication is contributing the most, rather than assuming lithium is the problem and discontinuing it, can lead to better outcomes on every front.

How Lithium Compares to Other Mood Stabilizers

A study comparing sexual function across different mood stabilizer regimens in long-term stable bipolar patients found that lithium fared worse than some alternatives. Patients taking anticonvulsant mood stabilizers (the “A group” in the study, referring to drugs like valproate or lamotrigine) had better total sexual function scores than patients on lithium alone or lithium combined with a benzodiazepine or an anticonvulsant. Specifically, lithium users had worse scores for sexual desire and arousal compared to the anticonvulsant group, while the lithium-plus-anticonvulsant and lithium-plus-benzodiazepine groups had worse orgasm scores.¹¹

The same study also found that being female and being older were both associated with worse sexual function scores across all treatment groups.¹² That suggests the relationship between lithium and sexual dysfunction is shaped by baseline vulnerability. A 25-year-old man starting lithium monotherapy faces a different risk profile than a 55-year-old woman adding lithium to an existing regimen of other medications.

These comparisons are not an argument against lithium. Lithium remains the best-studied mood stabilizer for suicide prevention and long-term mood stability, and its benefits often outweigh those of the alternatives. But for someone whose sexual health is a high priority, knowing that the mood stabilizer choice can affect sexual outcomes gives that person and their prescriber something concrete to discuss.

Premature Ejaculation and Other Specific Complaints

Most of the research focuses on reduced desire and erectile difficulties, but lithium has also been linked to changes in ejaculatory function. A published case report described a 33-year-old man with no previous medical history who developed premature ejaculation after starting lithium for bipolar disorder. The problem resolved quickly when the lithium dose was reduced. The authors attributed the mechanism to altered serotonin activity in the brain’s ejaculatory control centers, because lithium is known to modify serotonin receptor sensitivity.¹³

This case is a reminder that “sexual dysfunction” is not one thing. Lithium can reduce desire, impair arousal or erection, delay orgasm, or in some cases speed it up. Different mechanisms likely produce these different effects, which is part of why the overall picture is hard to summarize with a single number. If you experience a change in any domain of sexual function after starting or adjusting lithium, it is worth raising with your prescriber specifically. Saying “I have sexual side effects” is less useful than describing what changed: desire dropped, erections are weaker, orgasm takes longer, or ejaculation happens too quickly. The specifics can guide the response.

The Aspirin Trial

One of the more surprising entries in this literature is a randomized, double-blind, placebo-controlled trial testing aspirin as a treatment for lithium-associated sexual dysfunction in men. The rationale was straightforward: if lithium impairs nitric oxide signaling, and aspirin affects the cyclooxygenase pathway that interacts with nitric oxide production, then aspirin might partially counteract the problem. The results were striking. By week six, patients taking aspirin showed roughly a 64% improvement in their total sexual function scores from baseline, compared to about 14% improvement in the placebo group. For erectile function specifically, the aspirin group improved by about 85% while the placebo group improved by about 20%. Eighty percent of the aspirin group met the threshold for a clinically meaningful change, compared to 20% of the placebo group.¹⁴

These are impressive numbers, but they come from a single small trial of 30 patients, and the findings have not yet been replicated in a larger study. The chronic lithium rat study mentioned earlier found a clue that may help explain why aspirin works: indomethacin, another cyclooxygenase inhibitor, actually improved erectile tissue relaxation in lithium-treated rats while decreasing it in controls.⁶ That hints that lithium shifts the balance between pro-relaxation and pro-constriction pathways in blood vessels, and blocking certain prostaglandins can tilt it back. If your prescriber is open to it, low-dose aspirin is an inexpensive and relatively safe add-on worth discussing, though it carries its own risks for people with bleeding disorders or certain stomach conditions.

Why This Side Effect Gets Overlooked

Researchers who have reviewed this area are remarkably candid about how understudied it is. One review titled its discussion bluntly: lithium and sexual dysfunction is “an under-researched area.”⁷ The reasons are not mysterious. Bipolar disorder itself affects sexual behavior. Manic episodes commonly involve hypersexuality, and depressive episodes commonly involve loss of desire. That makes it hard to separate the drug effect from the disease effect in studies, especially when study designs do not include a washout period or a pre-treatment baseline. Many trials that measure lithium’s efficacy for mood stabilization either do not measure sexual side effects at all or lump them in with other side effects as a general tolerability score.

There is also a self-reporting problem. Patients do not always volunteer information about sexual difficulties, and clinicians do not always ask. The study that found a third of lithium patients affected specifically used a structured questionnaire to measure sexual function; rates drop in studies that rely on spontaneous patient reporting. This means the one-third estimate, while higher than some earlier figures, may actually be closer to the real prevalence than smaller numbers from studies that waited for patients to bring up the topic on their own.

Women and Lithium-Related Sexual Dysfunction

Almost all of the mechanistic research on lithium and sexual function has been done in male tissue or male animal models, which creates a real blind spot. The nitric oxide pathway is also involved in female genital arousal, so there is reason to believe similar mechanisms are at play, but specific studies are scarce. The comparative mood stabilizer study found that being female was independently associated with worse sexual function scores across all subscales.¹² Whether that reflects a stronger drug effect in women, a greater willingness to report problems on the questionnaire, or the confounding influence of age and hormonal status is unclear.

For women taking lithium, the practical upshot is worth stating plainly: if your desire, arousal, or ability to reach orgasm has changed since starting treatment, you are not imagining it, and you are not alone. The evidence base is thin, but the problem is acknowledged in the literature. Thyroid screening is especially relevant here, since lithium-induced hypothyroidism is more common in women and produces symptoms that overlap substantially with sexual dysfunction, including fatigue, weight gain, and reduced libido.

Fertility as a Separate Concern

Sexual function and fertility overlap but are not the same thing. The environmental lithium cohort study found that higher lithium exposure was associated with lower sperm motility and sperm concentration in men, and animal experiments in the same study showed structural damage to the testosterone-producing Leydig cells at the highest doses.⁹ The review of psychotropics and male reproduction similarly noted that lithium can decrease testosterone and shift other reproductive hormones.⁸

For someone of reproductive age taking lithium, this is a distinct conversation to have with a prescriber, separate from any discussion of sexual enjoyment. A semen analysis can give a concrete answer about whether lithium is affecting sperm parameters. Testosterone levels are easy to check with a blood draw. These tests are especially worth considering if you are planning to conceive, because the effects on sperm quality may be reversible if the drug is adjusted or paused under medical supervision, though stopping lithium carries its own serious risks for mood stability.