What to know about mirtazapine
Mirtazapine belongs to a group of medicines called tetracyclic antidepressants. These medications help balance the chemical messengers, or neurotransmitters, in the brain that regulate mood.
Mirtazapine is available on prescription, but not all pharmacies stock it.
In this article, we provide an overview of mirtazapine, including its uses, side effects, and interactions and how to take it.
Research suggests that mirtazapine could help treat depression, sleep problems, and poor appetite.
Image credit: Lanfear's Bane, 2008
Healthcare professionals primarily prescribe mirtazapine to treat depression.
According to a review of studies, mirtazapine is also effective in treating people with the following subtypes of depression:
- depression with anxiety
- melancholic depression
- treatment-resistant depression
- geriatric depression
- depression and anxiety relating to alcohol dependence
The authors also noted that mirtazapine could effectively help with:
- nausea after an operation
- sleep problems
- poor appetite
- pain management
How to take mirtazapine
Mirtazapine comes as either an oral tablet or a dissolvable tablet. The dosages for both types are the same.
According to the Food and Drug Administration (FDA), the recommended starting dose is 15 milligrams (mg) a day. People should preferably take it in the evening before going to bed.
The effective range of dosage for mirtazapine is between 15 mg and 45 mg a day. If necessary, with a doctor's approval, a person may increase the amount gradually after 1–2 weeks.
The tablets come in the following doses:
- 15 mg
- 30 mg
- 45 mg
Some healthcare professionals may recommend splitting the dose in two and taking one-half twice a day.
People should swallow the oral tablet whole without chewing it. If a person has difficulty swallowing pills, a healthcare professional may prescribe the dissolvable tablet instead.
To take a dissolvable tablet, the person will need to break the tablet out of the blister container, place it on their tongue, and wait for it to dissolve. It should dissolve reasonably quickly.
A person should follow their prescribed dosing and not attempt to adjust their dosage on their own or purposefully skip doses.
Side effects of mirtazapine include sweating, a dry mouth, and lightheadedness.
There are some side effects that a person may experience when taking mirtazapine. However, these side effects are generally mild, and not everyone experiences them.
Mild side effects of mirtazapine can include:
- dry mouth
- weight gain
- increased appetite
Serious side effects are rare, but they can sometimes occur. A person should tell their doctor right away if they experience:
People should get immediate medical attention or call the emergency services (911 in the United States) if they experience any of the following after taking mirtazapine:
- a fast or irregular heartbeat
- eye pain, swelling, or redness
- severe dizziness
- widened pupils
- changes in vision
In addition, although it is uncommon, people can experience allergic reactions to mirtazapine. If a reaction occurs, a person should seek emergency medical help. Some signs to look out for include:
- swelling or itching of the face, tongue, or throat
- trouble breathing
- severe dizziness
Finally, mirtazapine may very occasionally increase a person's serotonin levels. This effect could place a person at risk of developing serotonin syndrome, particularly if they are also taking other medications that can increase these levels.
People should seek emergency medical attention if they experience any of the following signs of serotonin syndrome:
- loss of coordination
- severe nausea, diarrhea, or vomiting
- fast heartbeat
- unusual agitation or restlessness
- unexplained fever
- severe dizziness
- twitching muscles
There are some precautions and warnings that a person should consider before taking mirtazapine.
Mirtazapine carries a black box warning, which is a warning label that the FDA use to signal the risk of potentially very dangerous side effects.
Suicidal thoughts or actions
Some research has linked taking the drug with increase suicidal thoughts or actions in children, teenagers, and young adults. The risk seems to reduce after the age of 24 years, and people are more prone to these effects when they first start taking the drug.
When a person starts taking mirtazapine or any other antidepressant, they should pay close attention to how they are feeling and talk to their healthcare provider about any new or sudden changes in their mood, behavior, thoughts, or feelings.
Before taking mirtazapine, a person should talk to their doctor about their history or family history of psychiatric disorders and suicidal thoughts or actions.
Mirtazapine may increase the risk of a person developing a condition called QT prolongation, which affects the rhythm of the heart. In rare cases, QT prolongation can cause:
- extremely fast or irregular heartbeat
Sleepiness or dizziness
Mirtazapine can cause sleepiness or dizziness. For this reason, a person should avoid using heavy equipment or driving after taking mirtazapine.
A person should not stop taking mirtazapine suddenly. Abruptly stopping this medication can lead to the following symptoms:
- tingling or prickling sensations
- nausea or vomiting
People who are stopping their use of the drug should work with their healthcare provider to come off it gradually.
Women should only use mirtazapine if they have no other options during pregnancy. When a woman uses it during the last few months of pregnancy, it is possible that the newborn may experience:
- trouble feeding
- difficulty breathing
- muscle stiffness
- uncontrollable crying
Researchers do not know whether mirtazapine passes through breast milk. Anyone who is breastfeeding should talk to their doctor before using this medication.
- If you know someone at immediate risk of self-harm, suicide, or hurting another person:
- Call 911 or the local emergency number.
- Stay with the person until professional help arrives.
- Remove any weapons, medications, or other potentially harmful objects.
- Listen to the person without judgment.
- If you or someone you know is having thoughts of suicide, a prevention hotline can help. The National Suicide Prevention Lifeline is available 24 hours a day at 1-800-273-8255.
Mirtazapine interacts with several different drugs. Drug interactions can prevent the medication from working in the usual way, and they can lead to dangerous side effects.
To help avoid these, a person should discuss all their medications, including both over the counter and prescription drugs, with their healthcare provider before starting mirtazapine. They should also make them aware of any vitamins or other supplements that they are taking.
Certain medications increase the risk of a person developing serotonin syndrome. A person should not take any of the following when taking mirtazapine:
- monoamine oxidase inhibitors (MAOIs)
- intravenous methylene blue
- an antibiotic called linezolid (Zyvox)
Other medications can cause or increase the risk of side effects, including the following:
- lithium, triptan, and serotonergic medications may increase a person's risk of developing serotonin syndrome
- benzodiazepines may promote drowsiness
- warfarin may increase the risk of heavy bleeding
- any medication that affects the heart's rhythm, including some antipsychotics or antibiotics, can worsen side effects
Other medications may increase the amount of mirtazapine in a person's body. These include:
- phenytoin (Dilantin)
- carbamazepine (Tegretol)
In other cases, medications may increase the body's exposure to mirtazapine, which can cause more side effects for the person. If a person takes one or more of the following, their healthcare provider may decrease the amount of mirtazapine that they take:
- protease inhibitors for HIV
- cimetidine (Tagamet)
If a person does not have insurance to cover the cost of mirtazapine, they could consider a prescription discount card.
The cost for mirtazapine will vary depending on a person's insurance coverage. A doctor typically needs to get approval from an insurance company before prescribing the medication.
Following approval, a person will pay their typical medication rates for a 30 day supply.
Those without insurance should consider using a prescription discount card to make the purchase as it could save them some money off the retail price.
Mirtazapine vs. related drugs
Medications work differently for different people. A person may respond very well to mirtazapine and not do well on other antidepressants. It is best to discuss any concerns with a healthcare professional who can offer advice on what medication may work best.
Mirtazapine is a tetracyclic antidepressant that healthcare professionals prescribe to treat depression. Some people find that taking this medication can help relieve symptoms and improve their quality of life.
People can speak to a healthcare professional about any side effects of mirtazapine. Everyone responds differently to antidepressants. Some people may find that a different dosage or an alternative medication works better for them.
Doctors do not usually prescribe mirtazapine to children and teenagers because they are more likely to experience suicidal thoughts or actions as a side effect.
Before taking mirtazapine, a person should make their healthcare provider aware of all of the medications, vitamins, and supplements that they are taking. People should take mirtazapine according to their doctor's instructions. It is essential to always speak to a doctor before stopping taking the drug.