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Olanzapine / samidorphan Side Effects

Medically reviewed by Last updated on Aug 19, 2022.

Applies to olanzapine / samidorphan: oral tablet.


Oral route (Tablet)

Warning: Increased Mortality in Elderly Patients with Dementia-Related PsychosisElderly patients with dementia-related psychosis treated with antipsychotic drugs are at an increased risk of death. Olanzapine/samidorphan is not approved for the treatment of patients with dementia-related psychosis.

Serious side effects

Along with its needed effects, olanzapine / samidorphan may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking olanzapine / samidorphan:

Less common

  • Black, tarry stools
  • burning, crawling, itching, numbness, prickling, "pins and needles", or tingling feelings
  • chills
  • cough
  • difficulty in speaking
  • dizziness
  • fever
  • headache
  • inability to sit still
  • lack or loss of strength
  • loss of memory
  • lower back or side pain
  • need to keep moving
  • nosebleeds
  • numbness or tingling in the face, arms, or legs
  • pale skin
  • problems with memory
  • relaxed and calm
  • restlessness
  • shakiness in the legs, arms, hands, or feet
  • sleepiness
  • sore throat
  • sores, ulcers, or white spots in the mouth
  • trembling or shaking of the hands or feet
  • trouble breathing
  • unusual bleeding or bruising
  • unusual drowsiness, dullness, tiredness, weakness, or feeling of sluggishness
  • weight gain

Incidence not known

  • Absent, missed, or irregular menstrual periods
  • aching or discomfort in lower legs or sensation of crawling in legs
  • anxiety
  • bloating
  • blurred vision
  • chest pain or tightness
  • clay-colored stools
  • cold sweats
  • confusion
  • constipation
  • dark urine
  • decreased interest in sexual intercourse
  • diarrhea
  • difficulty in breathing
  • dizziness, faintness, or lightheadedness when getting up from lying or sitting position
  • double vision
  • dry mouth
  • fainting
  • fast heartbeat
  • flushed, dry skin
  • fruit-like breath odor
  • inability to have or keep an erection
  • inability to move the arms, legs, or facial muscles
  • inability to move the eyes
  • inability to speak
  • increased blinking or spasms of the eyelid
  • increased hunger
  • increased sweating
  • increased thirst
  • increased urination
  • itching, rash
  • large, hive-like swelling on face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
  • loss in sexual ability, desire, drive, or performance
  • loss of appetite
  • loss of bladder control
  • loss of consciousness
  • muscle cramps, aches, pain, or stiffness
  • nausea
  • pain, redness, or swelling in the arm or leg
  • pains in the stomach, side, or abdomen, possibly radiating to the back
  • painful or difficult urination
  • seizures
  • sever muscle stiffness
  • slow speech
  • sticking out of the tongue
  • stomachache
  • stopping of menstrual bleeding
  • stuttering
  • sweating
  • swelling of the breasts or breast soreness in both females and males
  • swelling of breasts or unusual milk production
  • swollen glands
  • trouble in swallowing
  • uncontrolled twisting movements of the neck, trunk, arms, or legs
  • unexpected or excess milk flow from the breasts
  • unexplained weight loss
  • unpleasant breath odor
  • unusual face expressions
  • vomiting
  • vomiting of blood
  • yellow eyes or skin

Other side effects

Some side effects of olanzapine / samidorphan may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Less common

Incidence not known

  • Painful or prolonged erection of the penis

For Healthcare Professionals

Applies to olanzapine / samidorphan: oral tablet.


The most commonly reported side effects included weight gain, somnolence, dyslipidemia, and dry mouth.[Ref]


Hyperlipidemia included random cholesterol levels of at least 240 mg/dL and/or triglyceride levels of at least 1000 mg/dL.[Ref]

Very common (10% or more): Weight gain (up to 25%), dyslipidemia (up to 14%), increased appetite (up to 11%)

Common (1% to 10%): Decreased weight, increased glycosylated hemoglobin

Frequency not reported: Metabolic changes

Postmarketing reports: Diabetic ketoacidosis, hyperlipidemia, rhabdomyolysis[Ref]

Nervous system

Very common (10% or more): Somnolence (up to 21%)

Common (1% to 10%): Akathisia, amnesia, bradykinesia, dizziness, dyskinesia, dystonia, extrapyramidal adverse events, extrapyramidal disorder, extrapyramidal symptoms, headache, lethargy, paresthesia, parkinsonism, sedation, speech disorder, tremor

Frequency not reported: Anticholinergic/antimuscarinic effects, cerebrovascular adverse reactions (in older patients with dementia-related psychosis), cognitive impairment, motor impairment, neuroleptic malignant syndrome, seizures, stroke, syncope, tardive dyskinesia

Postmarketing reports: Diabetic coma, restless legs syndrome[Ref]


Very common (10% or more): Dry mouth (up to 13%)

Common (1% to 10%): Constipation, dyspepsia, increased salivation, nausea

Frequency not reported: Dysphagia

Postmarketing reports: Pancreatitis, salivary hypersecretion, vomiting[Ref]


Common (1% to 10%): Back pain, increased blood creatine phosphokinase, muscle spasm, neck muscle spasm[Ref]


Common (1% to 10%): Asthenia, fatigue, increased waist circumference

Frequency not reported: Body temperature regulation, falls, increased mortality (in older patients with dementia-related psychosis), opioid withdrawal precipitation, risks with combination treatment with lithium/valproate, vulnerability to life-threatening opioid overdose

Postmarketing reports: Discontinuation reaction[Ref]


Common (1% to 10%): Decreased neutrophil count, neutropenia

Frequency not reported: Agranulocytosis, leukopenia[Ref]


Common (1% to 10%): Restlessness, schizophrenia

Postmarketing reports: Stuttering[Ref]


Common (1% to 10%): Increased blood pressure

Frequency not reported: Orthostatic hypotension

Postmarketing reports: Deep venous thrombosis, venous thromboembolic events[Ref]


Common (1% to 10%): Blood insulin increased

Postmarketing reports: Hyperprolactinemia[Ref]


Postmarketing reports: Allergic reaction, anaphylactoid reaction, angioedema[Ref]


Postmarketing reports: Pulmonary embolism[Ref]


Postmarketing reports: Priapism[Ref]


Postmarketing reports: Diaphoresis, drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome[Ref]


Common (1% to 10%): Abnormal liver function tests, increased ALT, increased AST

Postmarketing reports: Cholestatic liver injury, hepatitis, jaundice, mixed liver injury[Ref]


1. "Product Information. Lybalvi (olanzapine-samidorphan)." Alkermes, Inc (2021):

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.