What the label lists and what reports show
Olanzapine and samidorphan l-malate side effects
Olanzapine and samidorphan l-malate's FDA label: “Most common adverse reactions (incidence ≥5% and at least twice placebo): Schizophrenia (LYBALVI): weight increased, somnolence, dry mouth, and headache.” FAERS holds 1,582 reports naming it through July 30, 2026; the reaction reported most often, leaving out the conditions it is used for, product-use terms and outcomes, is contraindicated product administered (108 reports).
- No generic listed
- Boxed warning
Check it at the source: the olanzapine and samidorphan l-malate FDA label on DailyMed (effective January 31, 2026, Alkermes, Inc.); the FDA FAERS public dashboard.
What does the patient leaflet say about side effects?
From the patient leaflet: What are the possible side effects of LYBALVI?LYBALVI may cause serious side effects, including: See “ What is the most important information I should know about LYBALVI? ” Stroke (cerebrovascular problems) in elderly people with dementia-related psychosis that can lead to death. Opioid withdrawal. Do not take LYBALVI for at least 7 days after you stopped taking short-acting opioids and for at least 14 days after you stopped taking long-acting opioids. One of the medicines in LYBALVI (samidorphan) can cause opioid withdrawal that may be severe and cause hospitalization in people who are physically dependent on opioids. Talk to your healthcare provider if you have questions about the type of opioid you take. Risk of life-threatening opioid overdose. You should not start taking opioids for at least 5 days after you stop treatment with LYBALVI. […]
Source: FDA drug label, Alkermes, Inc., effective January 31, 2026 (SPL set 32ffddd1-4e2b-45d9-9b36-bb730167ec80), via openFDA; the full label on DailyMed
What does the label list?
From the label: adverse reactionsMost common adverse reactions (incidence ≥5% and at least twice placebo): Schizophrenia (LYBALVI): weight increased, somnolence, dry mouth, and headache.
Table 2: Adverse Reactions Reported in ≥2% of LYBALVI-Treated Patients and Greater than Placebo in a 4-Week Schizophrenia Trial
| Adverse Reaction | Placebo (N=134) % | LYBALVI (10 mg/10 mg, 20 mg/10 mg) (N=134) % |
|---|---|---|
| Weight increased | 3 | 19 |
| Somnolence | 2 | 9 |
| Dry mouth | 1 | 7 |
| Headache | 3 | 6 |
| Blood insulin increased | 1 | 3 |
| Sedation | 0 | 2 |
| Dizziness | 1 | 2 |
| Neutrophil count decreased | 0 | 2 |
Rows and numbers as the label prints them, under its own column headings (the first rows of a longer table where it runs on). A reaction in a trial table is not necessarily caused by the medicine, and trials differ from everyday use.
From the label: adverse reactions, continuedThe following adverse reactions are discussed in detail in other sections of the labeling: Increased Mortality in Elderly Patients with Dementia-related Psychosis [see Boxed Warning, Warnings and Precautions ( 5.1 )] Cerebrovascular Adverse Reactions, Including Stroke, in Elderly Patients with Dementia-Related Psychosis [see Warnings and Precautions ( 5.2 )] Precipitation of Opioid Withdrawal in Patients Who Are Dependent on Opioids [see Warnings and Precautions ( 5.3 ) ] Vulnerability to Life-Threatening Opioid Overdose [see Warnings and Precautions ( 5.4 )] Neuroleptic Malignant Syndrome [see Warnings and Precautions ( 5.5 )] Drug Reaction with Eosinophilia and Systemic Symptoms [see Warnings and Precautions ( 5.6 )] Metabolic Changes [see Warnings and Precautions ( 5.7 )] Tardive Dyskinesia [see Warnings and Precautions ( 5.8 )] Orthostatic Hypotension and Syncope [see Warnings and Precautions ( 5.9 )] Falls [see Warnings and Precautions ( 5.10 )] Leukopenia, Neutropenia, and Agranulocytosis [see Warnings and Precautions ( 5.11 )] Dysphagia [see Warnings and Precautions ( 5.12 )] Seizures [see Warnings and Precautions ( 5.13 )] Potential for Cognitive and Motor Impairment [see Warnings and Precautions ( 5.14 )] Body Temperature Regulation [see Warnings and Precautions ( 5.15 )] Anticholinergic (Antimuscarinic) Effects [see Warnings and Precautions ( 5.16 )] …
Source: FDA drug label, Alkermes, Inc., effective January 31, 2026 (SPL set 32ffddd1-4e2b-45d9-9b36-bb730167ec80), via openFDA; the full label on DailyMed
What do FAERS reports show?
1,582 reports list olanzapine and samidorphan l-malate among the medicines taken, each a report of something that happened, not proof the medicine caused it; 16 are coded as a death and 169 as a hospital stay. Counts follow how widely a medicine is used and watched, and they are not a measure of how risky it is. Of the 23 reactions below, 8 are named by the same term (in US spelling) in the label's adverse reactions, warnings or patient leaflet; a reaction the label does not name may still be there under another word, and a report does not show that the medicine caused it.
Reports received each year
The 25 most reported reactions
Source: FDA Adverse Event Reporting System (FAERS) via openFDA, reports through July 30, 2026; reactions as MedDRA preferred terms
What next?
- Olanzapine and samidorphan l-malate: the full record
- label, generics, price, shortages, recalls
- Report a side effect to the FDA
- MedWatch
- Side effects hub
- the most reported medicines and reactions