How long does Mirtazapine stay in your system?

This article will discuss the approximate time taken by Mirtazapine to stay in your system. We will also discuss some factors that can affect this time duration and some proper ways to ensure the safe use of this antidepressant.

How long does Mirtazapine stay in your system?

Mirtazapine stays in your system for about 4-9 days (100-200 hours). However, the stay time of the medication in your body or its duration of action can depend on different factors – which is why it can vary from person to person (1). 

What is the half-life of Mirtazapine?

Mirtazapine has a half-life of about 20-40 hours, which is the time taken by the antidepressant to reduce its concentration to half (1,2). The remaining concentration of the drug further reduces to its half within the next 20-40 hours. 

This process continues until the drug is completely removed from your body. According to basic clinical studies, it typically takes 5 half-lives for a drug to get eliminated, which means Mirtazapine roughly stays in your body for about 4-9 days (1,2). 

It is also worth mentioning that Mirtazapine, as it is not a controlled drug or a substance of abuse, do not show up on a drug test. So, if you have a drug test coming up, you do not need to discontinue the medication or change your regimen.

What factors can affect the stay time of Mirtazapine in your system? 

Several factors can affect the stay time of Mirtazapine in your body, including (1):

Dosage strength 

The dose of Mirtazapine you take matters because higher doses generally take longer to be processed and eliminated. If you’re taking a lower dose, it might leave your system more rapidly.

Liver performance

The liver plays a crucial role in breaking down drugs (3). If your liver is healthy and functioning well, it can efficiently metabolize Mirtazapine, leading to a normal elimination rate. However, if you have liver issues, the drug might take longer to be cleared from your body.

Use of other medications

Some drugs can interact with Mirtazapine and affect how it’s metabolized. 

Certain medications may slow down or speed up the elimination of Mirtazapine, which can impact how long it remains in your system. It’s essential to inform your doctor about all the medications you’re taking to avoid potentially harmful interactions. 

Individual’s metabolism

An individual’s metabolism determines how quickly the person breaks down substances, including medications. 

If you have a fast metabolism, you might process Mirtazapine more quickly, leading to a shorter duration in your system. Conversely, a slower metabolism means Mirtazapine could stay in your body for a longer time.


Our genetic makeup plays a significant role in how our bodies respond to medications. Genetic factors can influence the enzymes responsible for breaking down Mirtazapine, leading to variations in the stay time among individuals.

How to ensure the safe and effective use of Mirtazapine?

The following points are important to ensure the safe and effective use of Mirtazapine (1,4):

  • Always take Mirtazapine as directed by your health care provider. Do not exceed the prescribed dose or duration of drug administration.
  • Do not stop the medication abruptly. If you are concerned about the side effects, talk to your doctor.
  • If you have missed a dose, try taking it as soon as you remember. If the next dose is near, skip the missed dose and take the next one on time.
  • Do not share Mirtazapine with anyone.
  • Avoid cutting the tablet in half without consulting your doctor first. 
  • Avoid grapefruit juice and any other medication or supplement that can affect the chemicals in your brain. If you’re unsure about the medications and supplements you are taking, please talk to your doctor or pharmacist.
  • Keep the medication out of reach of children or any such individual that may accidentally or willingly take it. 
  • Keep updating your doctor about the side effects you are experiencing. 

These points are important to make sure that you are using Mirtazapine in the best possible way. If you have any concerns about your treatment with Mirtazapine, you should reach out to your healthcare provider. 


In this article, we have discussed the approximate time taken by Mirtazapine to leave your system. We have also talked about some factors that might affect the duration of action of this antidepressant and some proper ways to ensure safe and effective use.

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Jilani TN, Gibbons JR, Faizy RM, Saadabadi A. Mirtazapine. 2022 Sep 7. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan–. PMID: 30085601.


PubChem [Internet]. Bethesda (MD): National Library of Medicine (US), National Center for Biotechnology Information; 2004-. PubChem Compound Summary for CID 4205, Mirtazapine; [cited 2023 Aug. 10]. Available from:


Almazroo OA, Miah MK, Venkataramanan R. Drug Metabolism in the Liver. Clin Liver Dis. 2017 Feb;21(1):1-20. doi: 10.1016/j.cld.2016.08.001. Epub 2016 Oct 15. PMID: 27842765. Available from:


The  Food and Drug Administration (FDA). HIGHLIGHTS OF PRESCRIBING INFORMATION. REMERON® (mirtazapine) tablets, for oral use. Available from:,%20021208s019lbl.pdf

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