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Shedding Light on the Risks
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Shedding Light on the Risks
& Benefits of Medications Could Zepbound Make Lithium Toxic? What New Case Reports Suggest
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The weight-loss medication may cause lithium levels to rise in the blood, potentially increasing the risk of toxicity. Experts explain what patients should know
November 10, 2026
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A case report published in October 2026 suggests that lithium, a psychiatric medication typically prescribed for bipolar disorder, may interact with GLP-1 medications.
The report, by psychiatrist Dr. Jay Davis and colleagues at the University of Colorado Anschutz Medical Campus in Aurora, was published in the Journal of Clinical Psychopharmacology. It describes a 50-year-old woman who told her doctor she was experiencing hand tremors, slurred speech, and blurred vision.
She had long been taking lithium for bipolar disorder, but about three weeks earlier she had started the weekly injection tirzepatide (Zepbound) for weight management. Since then, she said, she had felt full sooner and eaten smaller meals.
Lab tests showed the level of lithium in her blood had risen, from 0.7 to 1.2 mmol/L. Her doctor halved her nightly lithium dose, from 900 mg to 450 mg, and her symptoms resolved. Because the symptoms improved after the dose cut, the authors suspected a drug interaction. The woman and her doctor decided not to restart tirzepatide.
It is one of a handful of such case reports suggesting a possible interaction between lithium and GLP-1s.
Why Might GLP-1s Affect Lithium Levels?
Ritu Goel, M.D., a board-certified psychiatrist who also serves as an investigator in psychiatric clinical trials and is a member of MedShadow’s Health and Medical Advisory Panel, suspects the effect may be indirect. Because lithium is cleared almost entirely by the kidneys, reduced food, fluid, or sodium intake associated with GLP-1 use could cause the body to retain more of the drug.
But that may not be the full explanation, Dr. Goel cautions, since some patients described in the case reports experienced elevated lithium levels without gastrointestinal symptoms. It remains unclear exactly how GLP-1s might affect lithium levels.
“Lithium is a very delicate, sensitive medication,” adds psychiatrist Yalda Safai, M.D., who is based in New York and Los Angeles. The drug has a very narrow therapeutic index, she says, meaning even small changes in its concentration in the blood can increase the risk of toxicity.
What People Taking Lithium and GLP-1s Should Know
Although the frequency of this potential interaction is unknown, Dr. Safai advises patients taking lithium to stay hydrated and eat regular meals.
Dr. Goel recommends that people taking lithium have their lithium levels and kidney function checked before starting a GLP-1 medication, with additional blood tests after starting treatment, increasing the dose, switching medications, or stopping treatment.
“I would monitor closely but not reduce the lithium dose pre-emptively,” she says.
Still, neither psychiatrist considers lithium use an automatic reason to avoid GLP-1 medications. “There’s no absolute contraindication to GLP-1s,” Dr. Safai says.
Lithium isn’t the only psychiatric medication that warrants extra attention when people also take GLP-1s. Some antipsychotics, such as Latuda (lurasidone) and Geodon (ziprasidone), must be taken with food to be properly absorbed, Dr. Safai notes. The seizure medication Trileptal (oxcarbazepine), sometimes used for mood disorders, can cause low sodium levels, making electrolyte monitoring another consideration.
Why People Need to Tell Their Doctors About GLP-1 Use
One challenge, Dr. Safai says, is that people don’t always tell their psychiatrists they’re taking GLP-1 medications. Some get the drugs through compounding pharmacies or telehealth companies, where prescriptions may be issued based solely on patients’ responses to an online questionnaire.
Dr. Safai worries about oversight of these prescribing practices. “The industry is very unregulated,” she says.
Other people might obtain GLP-1s outside their usual medical care, including from pharmacies in Mexico. “I’ve noticed a lot of these patients carry shame around that action, so they might not tell me,” she adds.
To address this, Dr. Safai now routinely asks her patients whether they’re taking a GLP-1 medication. She reassures them that they can tell her, explaining that she needs to know about their medications to monitor for potential interactions.
Still, it’s important to put the findings in perspective. Dr. Goel emphasizes that the evidence comes from only a handful of case reports. Researchers haven’t established how frequently lithium toxicity occurs among people taking GLP-1 medications, and there are no pharmacokinetic studies confirming an interaction.
“That justifies awareness among psychiatrists, not alarm,” she says. “This should not stop patients with bipolar disorder from getting GLP-1s, which have real cardiometabolic benefit.”
- Davis, J., Singhal, S., & Butterfield, A. (2026). Tirzepatide-associated lithium toxicity: A case report. Journal of Clinical Psychopharmacology.
- Burson, J. R., & Leung, J. G. (2026). Lithium toxicity following a change from semaglutide to tirzepatide for weight loss management. Mental Health Clinician, 16(1), 34–38.
- Patarroyo-Rodriguez, L., Leung, J., Philbrick, K., Choe, J., & Singh, B. (2026). Tirzepatide-associated lithium toxicity necessitating hemodialysis in previously stable bipolar I disorder. Journal of Clinical Psychopharmacology, 46(4), 488–490.
- Hikma Pharmaceuticals USA Inc. (2026). Lithium carbonate tablets and capsules [Prescribing information]. DailyMed.
- Slubicki, M., Avula, A., Schaffer, D. H., & Swoboda, H. D. (2026). Lithium toxicity. In StatPearls. StatPearls Publishing
- Sumitomo Pharma America, Inc. (2025). Latuda (lurasidone hydrochloride) tablets [Prescribing information]. DailyMed.
- Pfizer Inc. (2010). Geodon (ziprasidone hydrochloride) capsules [Prescribing information]. DailyMed.
- Novartis Pharmaceuticals Corporation. (2025). Trileptal (oxcarbazepine) tablets and oral suspension [Prescribing information]. DailyMed.
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