The short answer: Olanzapine causes the most weight gain of the common bipolar medicines, followed by quetiapine. Lithium and divalproex (valproate) also add weight for many people. Lamotrigine, lurasidone, lumateperone, cariprazine and aripiprazole showed little or no extra weight gain over placebo in short bipolar trials. Your prescriber weighs this risk against how well each medicine controls your mood.
Which bipolar medications cause the most weight gain?
The 2018 CANMAT and ISBD bipolar guidelines name the medicines most often linked to weight gain: olanzapine, clozapine, risperidone, quetiapine, gabapentin, divalproex and lithium. The same guidelines list carbamazepine, lamotrigine and ziprasidone as options with less weight gain. They add that lurasidone has a minimal effect on weight, while aripiprazole may add weight with longer use.
FDA labels give a common yardstick. Many report the share of trial patients who gained 7% or more of their starting body weight. For a person who weighs 180 pounds, 7% is about 12.6 pounds. Here is a rough ranking from the labels and the guideline, from most to least weight gain:
- Highest: olanzapine (Zyprexa), and olanzapine combined with fluoxetine or samidorphan.
- High to moderate: quetiapine (Seroquel), divalproex (Depakote), lithium.
- Low in short bipolar trials: aripiprazole (Abilify), cariprazine (Vraylar), lurasidone (Latuda).
- Close to placebo: lumateperone (Caplyta), lamotrigine (Lamictal).
This order is a guide, not a rule. People respond very differently. Short trials also understate gain that builds over months. For how these medicines work and when each is used, see our mood stabilizers guide.
How much weight do olanzapine and quetiapine add?
The Zyprexa label pools 13 placebo-controlled studies in adults with a median exposure of 6 weeks. In those studies, 22.2% of people on olanzapine gained at least 7% of their body weight, compared with 3% on placebo. The average gain was 2.6 kg (5.7 lb).
The long-term numbers are larger. In studies of at least 48 weeks, the average gain was 5.6 kg (12.3 lb). Of those patients, 64% gained at least 7% of their weight, 32% gained at least 15%, and 12% gained at least 25%. The label notes that meaningful gain occurred at every starting body mass index (BMI).
Lybalvi combines olanzapine with samidorphan and is approved for bipolar I disorder. Its label reports a 24-week trial in people with schizophrenia. Weight rose by an average of 4.2% on Lybalvi versus 6.6% on olanzapine alone. About 17.8% of the Lybalvi group gained 10% or more of their weight, compared with 29.8% on olanzapine. So it reduces gain but does not remove it. The label also says the effect of switching from long-term olanzapine to Lybalvi is unknown.
For quetiapine, the Seroquel label gives bipolar-specific figures for adults who gained 7% or more of their body weight:
- Bipolar mania, used alone for up to 12 weeks: 21% on quetiapine versus 7% on placebo.
- Bipolar mania, added to another medicine for up to 3 weeks: 13% versus 4%.
- Bipolar depression, up to 8 weeks: 8% versus 2%.
Low bedtime doses used for sleep can also add weight. Our article on low-dose Seroquel at bedtime covers that use.
Do lithium and valproate cause weight gain?
Yes, for many people, though the labels give fewer hard numbers. The Lithobid label lists "excessive weight gain" among lithium's reported adverse reactions. It also lists thirst and swelling of the ankles or wrists. The label does not give a percentage. The CANMAT guideline places lithium on its list of medicines most commonly linked to weight gain.
The Depakote label reports weight gain in 8% of people in migraine trials, versus 2% on placebo. In a high-dose epilepsy trial, 9% of the high-dose group reported weight gain, versus 4% on a low dose. Its short 3-week mania trials did not list weight gain among the common reactions. That short window likely missed slower gain. CANMAT links divalproex to both weight gain and diabetes.
If you are thinking about coming off lithium because of weight, read what happens if you stop taking lithium first. Stopping suddenly raises the risk of relapse. Never stop or cut a dose without your prescriber.
Which options are closer to weight neutral?
Several newer or older options had little effect on weight in bipolar trials:
- Lamotrigine: In two placebo-controlled bipolar I trials in the Lamictal label, weight gain appeared only among reactions seen in under 5% of patients. The label also warns about a rare but serious rash.
- Lurasidone: In the bipolar depression trial in the Latuda label, 2.4% of patients gained 7% or more of their weight, versus 0.7% on placebo. The average gain was 0.29 kg.
- Lumateperone: The Caplyta label says weight changes in 6-week bipolar depression trials were similar to placebo. In a 6-month open-label study, average weight change was -0.01 kg.
- Cariprazine: In bipolar depression trials in the Vraylar label, 3% gained 7% or more on either dose, versus 1% on placebo.
- Aripiprazole: In 3-week bipolar mania trials in the Abilify label, 2.2% gained 7% or more, versus 2.7% on placebo. CANMAT notes that longer use may still add weight.
Most of these trials lasted 3 to 8 weeks. Short trials cannot show everything that happens over years. Lower weight risk also does not mean a medicine fits your illness. Each drug treats different phases of bipolar disorder.
How should weight be monitored on these medicines?
CANMAT advises that people on atypical antipsychotics have their weight checked monthly for the first 3 months, then every 3 months. It also advises blood pressure, fasting glucose and cholesterol checks at 3 and 6 months, then yearly. The guideline says people with a normal BMI still need these checks, because metabolic problems can occur without obvious weight gain.
Weight gain matters for more than appearance. CANMAT notes that weight gain is one of the most common treatment-related reasons people stop their medicine. Stopping without a plan is a major cause of relapse. Early, regular checks make it easier to act before the gain becomes large.
What can you do if a medicine is causing weight gain?
Talk to your prescriber early, ideally when you first notice your weight or appetite rising. Options they may discuss include:
- Changing the dose or timing, within the labeled range.
- Switching to a medicine with a lower weight risk that still treats your pattern of episodes.
- Adding diet, activity and sleep support.
- Checking for other causes, such as thyroid changes, which lithium can affect.
Keep a simple log of your weight, waist size and appetite. Bring it to each visit. Depression and weight changes often go together, and mental.md covers wider mental health care. Do not stop any bipolar medicine on your own, even if the weight gain is upsetting.
The bottom line
Olanzapine carries the highest weight gain risk among bipolar medicines, with quetiapine, divalproex and lithium also commonly adding weight. Lamotrigine, lurasidone, lumateperone, cariprazine and aripiprazole showed little extra gain in short bipolar trials. Ask for regular weight and metabolic checks, and raise concerns early. A good plan balances mood control and physical health.
Last updated: September 2026. This article is for informational purposes only and does not constitute medical advice. Do not start, stop or change any bipolar medicine without talking to your prescriber.