Olanzapine - Use | Dose | Side Effects

This article was medically reviewed by M.Pharm, Marko Tanaskovic on August 12, 2018. To read more about an author, click here.

Olanzapine is a second-generation antipsychotic drug and is used in the treatment of schizophrenia, moderate and severe manic episodes and to stabilize mood. It binds to the serotonin, cholinergic, histamine, adrenergic and dopamine receptors.


Contraindications to the use of the Olanzapine are:

  • Narrow-angle glaucoma
  • Allergy to the active substance

Olanzapine should not be used to treat psychosis that accompany dementia because clinical studies have shown that these patients are at higher risk of cerebrovascular adverse events.

This drug should not be used to treat psychosis that accompany Parkinson's disease, because studies have shown that it can lead to the worsening of the symptoms and to the occurrence of hallucinations.

There have been reported cases of Olanzapine-induced neuroleptic malignant syndrome1,2 which is characterized by the following symptoms:

  • Hyperpyrexia
  • Muscle stiffness
  • Rapid heartbeat
  • Mood swings

Neuroleptic malignant syndrome can have serious consequences for your health and can be life-threatening. Therefore, it is very important to immediately contact your doctor if you notice the symptoms of this syndrome.

The manufacturer of this drug states that Olanzapine should be used with extra precautions in diabetics, as there are reported cases of hyperglycemia caused by this drug.3

Olanzapine can increase blood cholesterol and triglyceride levels, therefore should be carefully applied to patients suffering from dyslipidemia.

It should be carefully applied in patients with liver damage since researches revealed that it causes the increase in the level of liver enzymes in the blood (AST, ALT, and LDH).

This drug can also cause neutropenia (decrease in the number of neutrophils in the blood), and if you notice signs of a weakened immune system, you should inform your doctor.

Olanzapine should not be discontinued abruptly because abrupt cessation of Olanzapine therapy can cause the following symptoms:

  • Nausea
  • Vomiting
  • Anxiety
  • Insomnia
  • Increased sweating
  • Tremor

Olanzapine can cause prolongation of the QT interval (seen on the ECG), and should not be used in patients who are taking medication which are also associated with prolongation of the QT interval, such as:

  • Antibiotics, such as: erythromycin, ciprofloxacin, levofloxacin, norfloxacin, ofloxacin and moxifloxacin.
  • Cimetidine (a drug used for the treatment of heartburn, GERD and gastric ulcers)
  • Terfenadine and astemizole (antihistamines used to treat allergic reactions)

Prolongation of the QT interval may cause severe arrhythmia.

Olanzapine should be administered cautiously in patients with family history of thromboembolic events, because it was determined that this drug can cause thromboembolism occasionally (0.1% - 1% of patients experience this side effect).

This drug should be administered cautiously in patients with epilepsy, because the data from clinical studies suggest that it may cause seizures.

Olanzapine can cause (especially if applied for a longer period of time) uncontrolled, involuntary and unusual movements of the tongue and face. Inform your doctor if you notice these symptoms.

This drug should not be used in patients younger than 18 years. In patients older than 65 years, blood pressure should be regularly checked while using this drug.

In addition, Olanzapine should be applied cautiously in the following conditions:

  • Paralytic ileus
  • Prostate disorders
  • Liver diseases
  • Kidney diseases

Olanzapine, pregnancy and breastfeeding

Newborns whose mothers took this drug in the last three months of pregnancy may experience the following side effects:

  • Breathing problems
  • Muscle weakness
  • Muscle stiffness
  • Drowsiness
  • Feeding difficulties

Olanzapine can be used during pregnancy only if the benefit to the mother outweigh the risks for the child. AU TGA and FDA classified this drug in group C.

Olanzapine is excreted into breast milk (approximately 1.8% of maternal dose passes into breast milk) and because of that breastfeeding should be avoided.


The usual starting dose for the treatment of schizophrenia is 10 mg per day.

Food does not affect the absorption of this drug so it can be taken regardless of meals.

Olanzapine exists in the form of oral dispersible tablets, which means that the tablet should be placed in the mouth where it will be dispersed rapidly under the influence of the saliva. You can also dissolve the tablet in a glass of water and drink that solution immediately after the preparation.

The starting dose in patients older than 65 years should be lower (5 mg daily).

Use of dose greater than 20 mg daily is not recommended.


Olanzapine should not be administered concurrently with the following drugs:

  • Bupropion (an antidepressant that is also used as a smoking cessation aid). Concomitant use increases the risk of seizures.
  • Propoxyphene (opioid analgesic). Concomitant use increases the risk of adverse effects on the central nervous system.
  • Tramadol (also an opioid analgesic). Concomitant use increases the risk of seizures.
  • Chlordiazepoxide and clorazepate (medicines used to treat anxiety and acute alcohol withdrawal). Concomitant use increases the risk of muscle weakness, drowsiness, difficulty breathing and hypotension.
  • Benzodiazepines (e.g. diazepam, alprazolam, bromazepam, and lorazepam). Co-administration of these drugs with Olanzapine increases the risk of hypotension.
  • Clozapine (an antipsychotic). Concomitant use increases the risk of serious heart problems.
  • Potassium preparations. Co-administration of the Olanzapine with potassium preparations increases the risk of stomach upset.
  • Fluvoxamine (a drug used in the treatment of depression, anxiety and social phobia). Fluvoxamine significantly increases the concentration of Olanzapine in the blood, which increases the risk of side effects.

Side effects

Olanzapine may cause the following side effects:

  • Neutropenia
  • Low blood sodium levels
  • Constipation
  • Tremor
  • Tardive dyskinesia
  • Increased appetite
  • Weight gain
  • Muscle stiffness
  • Muscle cramps
  • Hyperglycemia
  • Hypercholesterolemia
  • Hypertriglyceridemia
  • Fluid retention
  • Decreased libido
  • Hypotension
  • Bradycardia
  • Urinary incontinence
  • Thromboembolic undesired events
  • Arrhythmias
  • Sudden cardiac arrest and death
  • Liver damage


  1. NCBI link 1
  2. NCBI link 2
  3. NCBI link 3

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