10 Olanzapine Side Effects You Should Know About

When it comes to treating health conditions like bipolar disorder, schizophrenia, or even chemotherapy-induced nausea and vomiting, olanzapine (Zyprexa) is a common resource. Olanzapine is a once-daily medication that’s FDA approved to treat bipolar 1 disorder and schizophrenia in people age 13 and older. It’s an atypical antipsychotic that comes in several formulations, such as tablets, dissolvable tablets, and injections.

While olanzapine is a useful medication, it has some risks and side effects to be aware of.

Olanzapine side effects at a glance

Many of olanzapine’s side effects are relatively mild and manageable. They can slightly vary depending on what you’re taking it for.

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Common olanzapine side effects include:

• Sleepiness or a general lack of energy

• Insomnia

• Accidental injury

• Constipation

• Dry mouth

• Headache

• Dizziness

• Tremors, or shakiness

• High blood glucose (sugar), cholesterol, and/or triglycerides

• Weight gain

• Increased appetite

• Abdominal pain

• Low blood pressure when changing positions

Rare but serious risks include:

• High prolactin levels

• Low white blood cell counts, possibly leading to severe infection

• Movement problems such as tardive dyskinesia and neuroleptic malignant syndrome

• Abnormal changes in behavior or mood

• Seizures

• Serious skin rashes

• Trouble swallowing

• Body temperature changes

• Increased risk of death among older adults with dementia-related psychosis

• Increased risk of brain-related side effects among older adults with dementia-related psychosis

Here, we’ll delve into more detail on 10 notable olanzapine side effects. This list focuses on the oral version of the medication.

1. Feeling more or less sleepy than normal

Olanzapine may interfere with your sleep schedule. But the specific way it does so can vary.

Drowsiness (or sleepiness) is one of olanzapine’s most common side effects. This can have an effect on your mental alertness or judgment. On the other end of the spectrum, insomnia is another common side effect.

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If you feel tired after taking olanzapine, ask your healthcare professional about taking olanzapine around bedtime. And if you think olanzapine is contributing to a late night under the covers, ask them if it’s better to take your dose soon after waking up.

Drowsiness also appears to be dose-related, so you could ask them if a lower olanzapine dose may be better.

2. Constipation

Medications like olanzapine have anticholinergic properties. This means they can have a “drying” effect throughout your body. Constipation is one possible outcome of this.

If you develop constipation from olanzapine, certain dietary changes can help. Try to drink more water or slowly incorporate more foods that are high in fiber, such as whole grains, fruits, and vegetables. Fruits and vegetables that are high in water content can also help. Several over-the-counter medications for constipation are available when you need additional relief.

3. Dry mouth

Many medications can cause dry mouth, including olanzapine. This is likely due to its anticholinergic nature.

There are many ways you can try to treat dry mouth on your own. Drinking more water or improving salivation by sucking on ice chips, rinsing with cold water, or chewing sugarless gum can all help. But you could also ask a healthcare professional about saliva substitutes or possibly lowering your olanzapine dose. Dry mouth is more likely to happen with higher doses.

4. Headache or dizziness

Headache and dizziness are common with olanzapine. If you experience them, they should get better as your body gets used to the medication.

You can try to manage headaches with at-home remedies in the meantime. Boosting your water intake, partaking in stress-reducing activities, and engaging in light exercise can all make a positive difference. If you’re feeling dizzy, find a safe place to sit or lie down. Drink some fluids and eat a snack while you’re waiting for your symptoms to pass.

If headaches or dizziness don’t go away or get worse at any point, contact a healthcare professional for guidance.

5. Weight gain, alongside higher cholesterol and blood glucose

Olanzapine can cause metabolic changes, meaning it can worsen your blood glucose and cholesterol levels. It can also lead to a bigger appetite than normal. These can come together to contribute to weight gain.

This can become problematic, so your healthcare professional will likely monitor your blood glucose while you’re taking olanzapine — especially if you’re living with diabetes. They should also monitor your cholesterol levels and body weight over time.

Lifestyle changes, such as a nutritious diet and routine exercise, can help combat this. But if these changes become bothersome or severe, talk to your prescriber. They may switch you to another medication.

6. High prolactin levels

Olanzapine can raise prolactin levels. Prolactin is a natural hormone that’s found in our bodies, but too much of it can lead to side effects.

Common side effects of too much prolactin include a lower sex drive, menstrual irregularities, and mood changes. Gynecomastia (male breast development), nipple discharge, and fertility problems are also possible.

Olanzapine’s effect on prolactin doesn’t appear to get better the longer you take olanzapine, so let your healthcare professional know if any of these symptoms are affecting you. They’ll likely want to adjust your medication routine or offer others ways to help manage these symptoms. It’s hard to counteract high prolactin on your own.

7. Movement problems

Olanzapine can impact your body movements. It most often leads to shakiness or inability to sit still, but more serious risks are also possible.

Olanzapine can rarely cause tardive dyskinesia (TD). TD causes uncontrollable muscle movements, mostly of the face and tongue. Neuroleptic malignant syndrome (NMS) is also possible, and it can be life-threatening. NMS causes rigid muscles, fever, and confusion.

If you notice any signs of unusual body movements, let your healthcare professional know as soon as you can. These symptoms can be hard to get rid of — especially if left untreated — so they may tell you to stop taking olanzapine. But if your symptoms feel severe, it’s better to call 911 or seek emergency medical attention right away.

8. Behavioral changes

Some people experience changes in mood or behavior while taking olanzapine. Some of this is intended; olanzapine aims to promote positive behavioral changes by the way it works. But some of these changes can be unintentional or negative.

There are some reports of new or worsening depression with olanzapine, especially within the first few months of starting it. This includes thoughts of suicide. Make sure to contact your healthcare professional right away if you develop symptoms like these.

For additional resources or to connect with mental health services in your area, call SAMHSA’s National Helpline at 1-800-662-4357. For immediate assistance, call the National Suicide Prevention Lifeline at 988, or text “HOME” to 741-741 to reach the Crisis Text Line.

9. Serious skin rashes

Olanzapine very rarely causes serious skin rashes. It’s been linked to a condition called drug reaction with eosinophilia and systemic symptoms (DRESS). This typically starts as a rash, but it can cause fever and swelling throughout your body. If left untreated, DRESS can lead to organ damage and become life threatening.

If you develop a fever alongside symptoms like a rash, facial swelling, or swollen lymph nodes, call 911 or go to the nearest ER.

10. Complications related to dementia-related psychosis

Older adults who are experiencing hallucinations or agitation from dementia shouldn’t take olanzapine. Affected adults who take the medication are at a higher risk for death. Olanzapine has a boxed warning for this risk, the FDA’s most serious medication warning.

This same group of people shouldn’t take olanzapine for another reason. Olanzapine could raise the risk of experiencing a stroke or transient ischemic attack (“mini stroke”).

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Written by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

Reviewed by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

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