How long does olanzapine take to work for anxiety?

In this article:

• How long does it take to work?
• Influencing factors
• Dosage for anxiety
• Contraindications
• The bottom line

In this article

• How long does it take to work?
• Influencing factors
• Dosage for anxiety
• Contraindications
• The bottom line

Olanzapine (brand names Zyprexa or Zyprexa Zydis) is a second-generation antipsychotic medication that’s FDA approved to treat mental health conditions like schizophrenia and bipolar disorder, including mixed or manic episodes. It’s also approved for treatment-resistant depression or depression with bipolar I disorder in combination with fluoxetine. 

In recent years, olanzapine has been recognized for its effectiveness in managing anxiety disorders. It works by targeting dopamine and serotonin, neurotransmitters in the brain that enhance mood and alleviate anxiety symptoms.

If you’re taking olanzapine for anxiety, how soon will it start to work? Generally, you can expect to feel its effects within a few days to a couple of weeks, although this can vary from person to person.

How long does it take for olanzapine to work for anxiety? 

If you’re prescribed olanzapine for anxiety symptoms, you’re probably wondering how quickly you’ll start feeling better. Soon after taking it, you may feel more relaxed and calm. Most effects take between several days to two weeks to notice, and the effects will vary by patient, according to Charles Sweet, MD, a board-certified psychiatrist and medical adviser for Linear Health.

Zishan Khan, MD, a triple board-certified psychiatrist with Mindpath Health, explains that the onset of action also depends on dosage and formulation. For example:

• Olanzapine tablets (5-20 mg/day): While the medication’s effects typically begin within a few hours, Dr. Khan says full anxiety relief may take days to weeks.
• Orally disintegrating tablets (ODT): This form of olanzapine has slightly faster absorption than regular tablets, but results can take days to weeks.
• Intramuscular (IM) injection (5 mg/mL): This form is primarily utilized in acute settings, but Dr. Khan says it works quickly—within 15 to 45 minutes—for agitation or severe anxiety.

“Signs of improvement include less intense anxiety symptoms, better sleep, improved mood, and decreased feelings of agitation,” notes Dr. Sweet, adding that ideally, these positive effects build gradually over time. While patients starting on a lower dosage (5 to 10 mg) may find that olanzapine takes slightly longer to produce noticeable effects, starting at a higher dosage can increase the risk of side effects.

Common side effects of olanzapine include: 

• Increased appetite 
• Increased thirst or frequent urination
• Indigestion
• Weight gain
• Constipation
• Dizziness
• Drowsiness
• Dry mouth or increased salivation
• Fever
• Lack of energy
• Sleepiness
• Depression
• Restlessness
• Orthostatic hypotension (a sudden drop in blood pressure when moving from sitting to standing)
• Hyperglycemia (high blood sugar levels)
• Tremors or movement disorders
• Back pain
• Speech or vision changes
• Amnesia
• Tingling in the hands and feet

Serious side effects include:

• Increased risk of death in older adults who are confused, have memory loss, or have lost touch with reality (dementia-related psychosis)
• Severe hyperglycemia (high blood sugar) 
• High cholesterol and triglyceride levels in the blood
• Neuroleptic malignant syndrome (NMS), a rare nervous system reaction that causes symptoms like a high fever and muscle stiffness
• Drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome, a hypersensitivity reaction that causes fever, rash, facial swelling, enlarged lymph nodes, and kidney or liver injury
• Tardive dyskinesia, a movement disorder that causes uncontrolled body movements

It’s important to keep track of your symptoms and discuss any concerns with your healthcare provider.

What can affect how long olanzapine takes to work?

Factors that can affect absorption include food intake, gastrointestinal health, and the presence of other medications. Dr. Khan explains how these and other considerations can influence how fast olanzapine takes effect:

• Individual metabolism: An individual’s genetics and how they metabolize play a role, and as a result, a person may break down olanzapine faster or slower.
• Overall health: For example, if a person suffers from impaired liver function, they can notice a delayed drug breakdown, which can prolong its effects.
• Dosage: Higher doses may have a faster and stronger sedative effect. However, this will also increase the risk of side effects.
• Form: Injectable forms have a higher bioavailability and work faster than oral forms.
• Other medications: Some drugs, like carbamazepine, can speed up olanzapine metabolism, while other medications, such as fluvoxamine, can slow it down.
• Diet: Although food doesn’t significantly impact olanzapine’s absorption, consuming a high-fat meal may delay the peak effect.
• Other lifestyle factors: Hydration level and body weight can also play a role since dehydration or a very high BMI can alter the distribution of olanzapine within the body.

To enhance olanzapine’s onset of action, Dr. Khan recommends taking olanzapine on an empty stomach to speed up its absorption. He recommends avoiding alcohol, foods that are high in sugar, and consuming excessive amounts of caffeine, as all these can potentially worsen sedation, cause weight gain, and counteract olanzapine’s calming metabolic effects. Dr. Sweet adds that it’s advisable to limit high-fat meals, as they can delay the drug’s absorption of olanzapine. 

What is the standard olanzapine dosage for anxiety?

Olanzapine dosage varies based on the reason it’s being prescribed and the patient’s age. Standard doses for FDA-approved uses include:

• Schizophrenia and bipolar disorder: Initial dose of 5-10 mg, then up to 20 mg/day.
• Bipolar disorder (acute and maintenance): Initial dose of 10-15 mg, then up to 20 mg/day.
• Acute agitation: (usually by IM injection): 10 mg per dose, repeated as needed up to 30 mg/day.

For anxiety, which is an off-label use, Dr. Sweet says low doses of olanzapine may be prescribed, typically starting with 2.5-10 mg per day and adjusting from there as needed. “This dosage comes at the discretion of the prescriber and typically takes the individual’s history, condition, and response to the drug into consideration,” he adds.

Who should avoid taking olanzapine?

While olanzapine can be beneficial for many, certain individuals should avoid taking this medication:

• Older adults with dementia-related psychosis are at increased risk of stroke and death.
• Patients with a history of heart disease may be at increased risk of hypotension or irregular heartbeat.
• Individuals with liver disease are at increased risk of liver injury.
• Those with metabolic conditions have an increased risk of weight gain, diabetes, and dyslipidemia.  
• Pregnant or breastfeeding women should weigh the risks and benefits with a provider. Olanzapine can affect fetal development and may pass into breast milk.

Possible drug interactions include:

• Over-the-counter allergy medications
• CNS Depressants like alcohol, opioids, and benzodiazepines.
• Tricyclic antidepressants
• Selective serotonin reuptake inhibitors (SSRIs) 
• Serotonin-norepinephrine reuptake inhibitors (SNRIs)
• Blood-pressure lowering medications
• CYP enzyme inhibitors
• Other typical or atypical antipsychotic drugs
• Anticonvulsants

This is not a complete list of drug interactions, share a list of all over-the-counter medications, supplements, and prescriptions you are taking with your healthcare team.

The bottom line

Olanzapine can take several days to a couple of weeks to work for anxiety. Its onset of action can vary based on dosage, individual metabolism, and overall health. Remember, every journey is unique, and it’s essential to work with a healthcare professional to find what works best for you!