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What is mirtazapine used for?

Mirtazapine is used in various different conditions including:

• Depression
• Depression associated with bipolar disorder
• Anxiety disorders like post traumatic stress disorder and panic disorder
• Sleep disorders (insomnia)

Your doctor may be using this medication for another reason. If you are unclear why this medication is being prescribed, please ask your doctor.

How does mirtazapine work?

Mirtazapine increases the activity of certain chemicals in the brain called norepinephrine and serotonin. It is believed that some brain chemicals, such as norepinephrine and serotonin, are not working well in people who are depressed. The exact way that mirtazapine improves the symptoms of depression is still not fully known.

Mirtazapine in children and adolescents

Mirtazapine is mainly used in adults, but in certain cases, may be used with children and adolescents. Like many medications used to treat childhood disorders, mirtazapine has not been approved by Health Canada for use in children and adolescents.

When the potential benefits (e.g., reducing your symptoms) of using mirtazapine outweigh the potential risks (e.g., the side effects), many doctors may prescribe it.

How should mirtazapine be taken?

Mirtazapine is available either as a regular tablet or a tablet that dissolves in your mouth (Remeron SolTab®). It is usually taken once a day with or without food.

This medication should be taken at the same time each day (usually bedtime) as directed by your doctor. Try to connect it with something you do everyday (like brushing your teeth) so that you don’t forget. Try to avoid alcohol while taking mirtazapine.

If you are taking the dissolving tablets, follow these directions. Since this medication comes in a “blister pack” (not a bottle), you have to carefully take the medication out of the blister each time.

• Use dry hands to peel off the foil from the back of the blister before removing the tablet (wet hands can cause the medication to melt in your hands). Do not push the thin wafer through the foil.
• Place the tablet on your tongue. The tablet will dissolve quickly and may be swallowed with or without water. Try not to chew the tablet.

Usually, your doctor will start with a low dose of mirtazapine. Then, the dose will be gradually increased over several days or weeks based on how you respond to it. You and your doctor can then discuss the best dosage to stay on based on how well you tolerate this medication (how well the medication is working and how you are doing with the side effects of the medication) and how well it helps to decrease your symptoms.

When will mirtazapine start working?

Mirtazapine must be taken for 3 to 6 weeks before you begin to feel better. Different symptoms start to improve at different rates. For example, improvements in sleep, appetite and energy may be seen within the first 2 weeks.

Sometimes, others will notice improvements in you before you do. Full beneficial effects may take up to 4 to 8 weeks (or longer). Since this medication takes time to work, even if you are feeling better, do not increase, decrease or stop it without discussing with your doctor first.

If you are not feeling better within 6 to 8 weeks, your doctor may recommend you take a different medication. There is a small chance that your depressive symptoms may worsen or that you may experience increased thoughts of self harm during the first couple months of taking this medication (see section on side effects). If this happens, tell your doctor IMMEDIATELY.

How long do I have to take mirtazapine?

This depends on the symptoms you have, how frequently they occur and how long you have had them. Most people need to take this medication for at least 6 months. This allows time for your symptoms to stabilize and for you to regain functioning. After this time, you and your doctor can discuss the benefits of continuing treatment.

If you have had several episodes of severe depression and you tolerate this medication well, you may be asked to take this medication for an indefinite amount of time. By continuing to take this medication, you significantly decrease the chance that you may have another episode of depression. Do NOT stop taking this medication (even if you are feeling better) without discussing it with your doctor first. If you stop taking this medication suddenly, it is possible that your symptoms may return or you may have a bad reaction.

Once you have started taking this medication, you and your doctor will need to monitor for both the beneficial and unwanted effects. Your doctor will check your progress and discuss changes in symptoms during the next 3 months

to confirm that the medication is working properly and that possible side effects are avoided. At this time, you can discuss how long you might need to take this medication.

Is mirtazapine addictive?

No, mirtazapine is not addictive. You will not have “cravings” for it like some people do with nicotine or street drugs.

If you and your doctor decide it is best for you to stop taking mirtazapine, your doctor will explain how to safely lower the dose so you won’t feel any unpleasant “flu-like” effects (chills, nausea, vomiting, dizziness, tingling in hands and feet, muscle aches, fever and electrical sensations) as your body adjusts to being without this medication.

What are the side effects of mirtazapine and what should I do if I get them?

As with most medications, side effects may occur when taking mirtazapine. Most side effects are mild and temporary. Side effects may occur before any of the beneficial effects. It is possible for some individuals to experience side effects that they feel are serious or long lasting. If this occurs, speak to your doctor about ways to manage them.

Below are some of the common side effects and potentially serious side effects of taking this medication, and in brackets are suggested ways to lessen these effects.

Common side effects

Side effects may be more common when starting a medication or after a dose increase. If any of these side effects is too troublesome for you, please discuss them with your doctor, nurse or pharmacist.

• Constipation (increase exercise, fluids, vegetables, fruits and fiber intake)
• Drowsiness and tiredness (take the dose at bedtime; this usually lessens over time)
• Dry mouth (try chewing sugarless gum, sour candies, ice chips, or popsicles)
• Dizziness (try getting up slowly from a sitting or lying down position)
• Energized/agitated feelings (avoid caffeine from energy drinks, colas and coffee)
• Increased hunger (avoid high calorie foods)
• Stomach aches or nausea (try taking the mirtazapine dose with food)
• Unusually vivid dreams
• Weight gain (monitor your food intake, increase your exercise)

Uncommon side effects (e.g., those that occur in less than 5% of patients)

Contact your doctor IMMEDIATELY if you have any of these side effects:

• A switch in mood to an unusual state of excitement, irritability or happiness
• Skin rash, itchy skin or hives
• Thoughts of self harm, hostility or suicide
• Uncomfortable sense of inner restlessness or agitation

What precautions should my doctor and I be aware of when taking mirtazapine?

Tell your doctor or pharmacist if you:

• Are lactose intolerant (mirtazapine tablets contain lactose)
• begin taking any other new medication (prescription or non-prescription), since several other medications
• can interact with mirtazapine
• feel drowsy, dizzy or slowed down. Mirtazapine can make some individuals experience these temporary
• side effects. Mirtazapine may increase the effects of alcohol, resulting in more sedation or dizziness.
• if you feel this way, it is important to avoid operating heavy machinery or driving a car.
• have a history of diabetes, heart disease, thyroid disease, kidney or liver disease or seizures
• have any allergies or have experienced a reaction to a medication
• have any changes in mood or thoughts of self harm
• if you develop any new medical problem while you are taking mirtazapine
• miss a period, become pregnant or are trying to become pregnant or are breast-feeding

What special instructions should I follow while using mirtazapine?

• Keep all appointments with your doctor and the laboratory.
• Do not allow anyone else to use your medication.
• It is a good idea to have a visit or telephone call with your doctor within 1-2 weeks after you start taking mirtazapine, and then periodically after that to see how well the medication is working, how well you are tolerating the medication, and to discuss any problems you may have.

What should I do if I forget to take a dose of mirtazapine?

If you take mirtazapine only at bedtime and you forget to take it, do not take the missed dose and continue with your regular dosing schedule the next day. Do NOT double your next dose. If you take mirtazapine more than once a day, take the missed dose as soon as possible. However, if it is almost time for your next dose (e.g., within 4 hours), do not take the missed dose and continue with your regular dosing schedule. Do NOT double your next dose.

What storage conditions are needed for mirtazapine?

• Keep this medication in the original container, stored at room temperature away from moisture and heat (e.g., not in the bathroom or kitchen).
• Keep this medication out of reach and sight of children.

Share this information

You may wish to share this information with your family members to help them to understand your treatment options. Since every person's needs are different, it is important that you follow the advice provided to you by your own doctor, nurse and/or pharmacist and speak to them if you have any questions about this medication.

About this document

Special thanks to the Kelty Centre for Mental Health for permission to adapt this document. The original document was developed by health professionals of BC Mental Health and Addiction Services, and reviewed by the staff of the Kelty Mental Health Centre. French translation provided courtesy of the Ontario Centre of Excellence for Child and Youth Mental Health.

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Disclaimer

Information in this pamphlet is offered ‘as is' and is meant only to provide general information that supplements, but does not replace the information from your health provider. Always contact a qualified health professional for further information in your specific situation or circumstance.