How Long Does Mirtazapine Take to Work?

Mirtazapine, the generic name for Remeron, is an atypical tetracyclic antidepressant that’s used to treat major depressive disorder (MDD). The medicine is also sometimes prescribed off-label — that is, for conditions not FDA-approved for this medication — to help manage panic disorder, insomnia, post-traumatic stress disorder (PTSD), generalized anxiety disorder (GAD), migraines, obsessive-compulsive disorder (OCD), and social anxiety disorder. 

It’s natural to wonder how long it takes for mirtazapine to work​. Understanding as much as possible about a drug you’re taking — including timelines — helps manage expectations about your treatment plan.

How Fast Does Mirtazapine Take to Work?

Mirtazapine works by increasing noradrenaline and serotonin levels in the brain to promote mood stabilization and enhance emotional regulation. It works differently than antidepressants in the popular class of drugs known as selective serotonin reuptake inhibitors (SSRIs). In studies, mirtazapine consistently had a higher efficacy than most SSRIs, especially at the beginning of treatment. 

Mirtazapine’s onset of action varies from person to person, and some people who take it see improvement in symptoms or mood changes within a week. That said, according to research, it can take between 4 – 8 weeks or longer to experience the full benefits of the drug. This is because mirtazapine isn’t a short-acting drug — levels build with consistent use, and your body needs time to adjust to having the drug in your system.   

• Weeks 1 – 2: Some of the earliest benefits of mirtazapine can be seen and felt within the first 1 -2 weeks of use. They can include better sleep, energy, and appetite. These are significant improvements to be aware of because they suggest the medication is working for you.   
• Weeks 6 – 8 (and beyond): Mood improvements — including reduced feelings of sadness, anxiety, and irritability — might need 6 – 8 weeks or longer before they’re fully felt. Some studies indicate that mirtazapine has a faster onset of antidepressant effects compared to SSRIs during the acute phase of treatment, which can be a plus when you’re trying to decide which medication is best for your symptoms and needs.

“As a therapist, I’ve seen Mirtazapine’s sedating effects provide quick relief for sleep issues, while its mood benefits take some weeks to develop. I remind clients to be patient and use coping strategies as their medication takes full effect while collaborating with their prescriber.”

– Talkspace therapist Bisma Anwar, LPC, LMHC

Factors That Affect How Long It Takes Mirtazapine to Work

Like any drug, multiple factors can affect how long it takes mirtazapine to work. Everything from your weight and age to the dosage you take to the condition being treated can impact efficacy and the length of time it takes a drug like mirtazapine to work. Follow your doctor’s or healthcare provider’s treatment plan closely to ensure symptoms improve on schedule and unwanted side effects are avoided. 

Dosage adjustments

Mirtazapine is available in multiple forms and dosages. It comes in oral tablets ranging from 7.5 mg to 45 mg and in oral disintegrating tablets between 15 and 45 mg. It’s not uncommon for your doctor to start you on a lower dose (like 15 mg per day) and then increase if needed. Changes in dosage typically won’t happen until you’ve been taking your current dose for at least 2 weeks so there’s enough time for your body to react. 

Condition being treated

What you’re taking mirtazapine for can also impact how long it takes to work. For example, if you’re taking this drug for insomnia, you’ll likely feel the sedative effects within an hour. When taking it for depression or another mental health condition, it can take several weeks to notice improvement. 

The severity of symptoms can also play a factor. If you have severe depression, it can take longer for mirtazapine to work for you than it might for someone with mild to moderate symptoms. 

Individual factors

Individual factors play a role in the timeline for any drug to work. Genetics, weight, metabolism, and other health conditions or medications can all impact efficacy and how long it takes mirtazapine to work for your symptoms. Some research found that specific differentially expressed genes (DEGs) can alter the response to treatment when using mirtazapine. 

Interaction with other medications

Mirtazapine’s safety and efficacy can be affected if you combine this drug with other medications. You shouldn’t use mirtazapine within 2 weeks of taking any monoamine oxidase inhibitors (MAOIs). There’s also an increased risk of serotonin syndrome if you take mirtazapine with other drugs that amplify serotonin production in the brain.

Always share every drug, medication, or supplement you’re using (both prescribed and over-the-counter) with your doctor or healthcare provider before you take mirtazapine. 

How to Know if Mirtazapine is Working

There are several indications that mirtazapine is working for you. The first is apparent changes or improvements in symptoms and general well-being. Other key, specific daily life indicators are explored below. 

Improved sleep patterns

Mirtazapine has known sedative properties that can lead to better sleep patterns, often within the first week or two of taking it. You might find that you can fall asleep faster and wake up fewer times throughout the night once you start mirtazapine. If you experience reduced insomnia-related issues after starting mirtazapine, it’s a good sign the drug is working for you. 

Increased energy levels

As your brain responds to the changes brought by mirtazapine, you might experience an increase in your energy levels. As your depression lifts, you’ll likely feel more energetic, motivated, and engaged in your daily activities and responsibilities. The reduction in fatigue and your newfound ability to start and complete tasks you previously struggled with or felt overwhelmed by can clearly show the drug is working. 

Better appetite

If you’ve been unable to eat or have lost weight due to your depression, mirtazapine is known to stimulate appetite. When the medication works, you might notice an increase in hunger and an improved interest in and enjoyment of food. 

Stabilized mood

Reduced mood swings and enhanced emotional stability indicate that mirtazapine is gradually having a positive impact on your symptoms. Look for fewer extreme or intense sadness episodes, and take note if you’re starting to feel more balanced overall. 

Enhanced motivation

When you feel good, you’re more likely to be willing to engage in work, social activities, and hobbies. Part of depression is the loss of interest in things you once enjoyed — regaining that spark for previously neglected passions can renew your sense of purpose and direction. 

Feedback from others noticing positive changes

It’s easy to get lost in your emotions and feelings, which can sometimes make it difficult to see your progress toward improving mental well-being. Notice if family members and friends start to remark on your mood or behavior. They might notice that you’re more positive, upbeat, or beginning to engage socially again before you do — all of these are signs that mirtazapine is working for you. 

“Clients should have realistic expectations by distinguishing Mirtazapine’s true effects from placebo responses. Early improvements in sleep or anxiety often stem from its sedative properties, while lasting mood benefits take weeks to develop. Clients should track changes over time and discuss concerns with their prescriber.”

– Talkspace therapist Bisma Anwar, LPC, LMHC

What to Do If Mirtazapine is Not Working

If you’ve been taking mirtazapine for several weeks but aren’t noticing any improvement in symptoms, you should talk to your doctor or a mental health professional. Despite being effective in studies, not all medications work the same way for everyone. Your doctor will likely discuss the following with you before deciding on next steps:

• Review your dosage to ensure it’s optimized for you
• Allow more time — remember that some people take longer to respond
• Assess adherence to your prescribed treatment plan
• Check for potential interactions with other medications or substances
• Consider mirtazapine alternatives
• Combine mirtazapine with other drugs and/or therapy for improved outcomes

If mirtazapine isn’t working as you hoped, do not stop taking the medication suddenly. Talk to your doctor first before stopping any medication to avoid the risk of mirtazapine withdrawal.

Get Personalized Mental Health Treatment with Talkspace

To find the most effective treatment for your depression or any other mental health condition, you should work with a healthcare provider or licensed mental health professional. The same plan might not work the same way for two different people — so the best way to ensure you get on the right path is by partnering with someone who’s experienced and you trust. 

When you work with Talkspace, you’ll be connected to online psychiatric providers who can prescribe mirtazapine online, adjust dosages when necessary, and offer guidance for your mental health treatment. Whether you’re just starting your journey or looking for ongoing support, Talkspace provides a convenient and confidential way to receive care online.

Connect with an online Talkspace psychiatrist today to explore personalized treatment options and get expert medication management, including prescriptions for mirtazapine (Remeron).