8 Olanzapine Interactions You Should Watch Out for

Every year in the U.S., 1 in 5 adults experience mental health conditions, such as bipolar disorder, schizophrenia, or depression. For many people, medication is a part of their treatment plan. Olanzapine (Zyprexa) is an atypical antipsychotic that can help improve the symptoms of these conditions.

Olanzapine can help regulate mood and behavior for people living with bipolar disorder and schizophrenia. When combined with fluoxetine (Prozac), it can also help treat depression when antidepressants haven’t worked well enough.

Olanzapine works by balancing levels of dopamine and serotonin in the brain. It’s broken down in the body by a specific enzyme (protein). There are many medications, supplements, and foods that interfere with this enzyme. This causes olanzapine interactions, which can change how either medication works or raise the risk of side effects.

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So what olanzapine interactions should you look out for? Let’s discuss eight notable ones to know.

1. Carbamazepine

Carbamazepine (Tegretol, Equetro) is an anti-seizure medication. It’s also sometimes prescribed for people living with bipolar disorder. It interacts with the enzyme that breaks down olanzapine. Carbamazepine can cause olanzapine to be cleared from the body faster. This can make olanzapine less effective. You may need a higher dose of olanzapine if you’re also taking carbamazepine.

2. Fluvoxamine

Fluvoxamine (Luvox) is a medication used to help treat the symptoms of obsessive-compulsive disorder (OCD). It interacts with olanzapine by slowing the enzyme that breaks it down. This can cause olanzapine levels to rise and raises the risk of side effects, like dizziness or drowsiness. Your healthcare provider may lower your dose of olanzapine if you’re taking fluvoxamine. 

3. Caffeine

Many of us find it hard to start the day without a cup of coffee. But if you’re taking olanzapine, you may have to make some changes to that morning routine. Caffeine can slow down how quickly olanzapine is broken down by your body. This means there could be more olanzapine in your body than intended. And this may raise your chances of experiencing olanzapine side effects.

But this interaction doesn’t mean you have to totally give up coffee. Talk to your healthcare provider about how long you should wait between caffeine and your olanzapine dose. Just keep in mind that caffeine is found in other places. Drinks, like soda and tea, and some medications, like Excedrin Migraine (acetaminophen/aspirin/caffeine), also have caffeine. So you’ll want to talk to your healthcare provider before taking these products.

4. Anticholinergic medications

Anticholinergic medications are used to treat a variety of health conditions like depression and excessive sweating. Medications like olanzapine can act like an anticholinergic medication even though they’re not classified as one. Taking olanzapine with an anticholinergic medication raises the risk of certain side effects, such as constipation, dry eye, and dry mouth.

There are situations where people may need to take both olanzapine and anticholinergic medications. In this case, your healthcare provider may ask you to watch for side effects. If you’re having any of these side effects, let them know.

5. Alcohol

Alcohol has many effects on the body. Most notably, it can make you sleepy, cause balancing problems, and affect your blood pressure. Olanzapine can also cause these side effects.

Drinking alcohol while taking olanzapine can make these side effects more intense. This raises your risk of falling and getting hurt. There’s also concern that alcohol can make olanzapine less effective.

It’s important to have an open conversation with your healthcare provider about whether you drink alcohol if you're taking olanzapine. There’s no hard and fast rule about how much alcohol is safe to drink with this medication. So your healthcare provider can help determine if there’s a safe amount for you to drink or if you should avoid alcohol altogether.

6. Diazepam

One possible side effect of olanzapine is a drop in your blood pressure. This usually happens when changing positions from sitting or lying down to standing. You may feel lightheaded, dizzy, or like you’re going to pass out. Diazepam (Valium) is an anxiety medication that can also cause low blood pressure. If you’re taking both olanzapine and diazepam, you may have a higher risk of experiencing this side effect.

Discuss this interaction with your healthcare provider if you’re taking both medications. They may ask you to check your blood pressure regularly. If you experience symptoms of low blood pressure, such as lightheadedness or blurry vision, contact your healthcare provider.

7. Blood pressure medications

Olanzapine doesn’t interact directly with blood pressure medications. But one possible side effect of these medications is low blood pressure. As discussed above, olanzapine also causes this side effect. Combining these medications can raise the risk of low blood pressure. In more severe cases, this could lead to falls and accidental injury.

If you’re taking blood pressure medication, you may already be checking your blood pressure at home. Discuss how often you should take blood pressure readings with your healthcare provider. You should also discuss what an ideal range is for you if you’re taking olanzapine and blood pressure medications. If you’re having any symptoms of low blood pressure (e.g., lightheadedness, weakness), let your healthcare provider know.

8. Activated charcoal

Activated charcoal is typically used in emergency poisoning situations or when someone has taken too much of a medication. It’s also sold as a dietary supplement for gas relief and digestion support. But it can prevent the body from properly absorbing olanzapine by binding to it in the stomach.

You shouldn’t take activated charcoal while taking olanzapine. The body takes several hours to fully absorb a dose of olanzapine. So taking activated charcoal during this time can prevent proper absorption.

When should I contact my healthcare provider about an olanzapine interaction?

You should contact your healthcare provider about an interaction if you feel that your moods and behaviors haven’t improved or have gotten worse. You should also reach out if you’ve been experiencing symptoms of low blood pressure, especially when changing positions. These may be symptoms of a potential olanzapine interaction.

You can help avoid or manage olanzapine interactions by having an open conversation with your healthcare provider and pharmacist about other medications you’re taking. Make sure to include all prescription and over-the-counter medications, supplements, and herbal remedies. It’s also important to be honest about any alcohol or other substances you may be using.

Just because there are many possible olanzapine interactions, it doesn’t always mean you’ll have to stop a medication. Extra monitoring may be all that’s needed to manage interactions. Don’t stop or change your dose of olanzapine without talking to your healthcare provider first.

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Written by:

Kristine Foley, PharmD

Kristine Foley is a licensed pharmacist with over 13 years of community pharmacy experience. She earned her Doctor of Pharmacy degree from Rutgers University.

Edited 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.

Reviewed by:

Stacia Woodcock, PharmD

Stacia Woodcock, PharmD, is a pharmacy editor for GoodRx. She earned her Doctor of Pharmacy degree from the University of Kentucky and is licensed in New York and Massachusetts.

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