Long-term Effects of Remeron

Last Updated on September 19, 2026 by Diane Ridaeus

Alternative to Meds Editorial Team
Medically Reviewed by ATMC Clinical Review Team

What is Remeron?

Remeron is classed as an atypical antidepressant. Unlike SSRIs or other types of antidepressants, it is tetracyclic, having a compound of four molecules in its chemical structure. Regulators believe Remeron influences a variety of receptors in the brain — noradrenaline and some (but not all) serotonin receptors in the main, plus histamine and choline receptors. The category for Remeron is NaSSA, an acronym meaning it is a Noradrenergic, and Specific Serotoninergic Antidepressant.^1,8

What is Remeron Prescribed to Treat?

In 1996, the FDA approved Remeron to treat MDD (major depressive disorder).

Off-label uses have also become prevalent, including treating PTSD, insomnia, OCD (obsessive-compulsive disorder), panic disorder, GAD (generalized anxiety disorder), headaches and migraines, SAD (social anxiety disorder), and others.¹⁰

Mirtazapine causes sedation when first used, which explains why it is sometimes prescribed off-label to treat insomnia. However, the sedative effects commonly fade after a short time. This property was demonstrated in rat studies such as the one published in the Brazilian Journal of Psychiatry. The study showed the sedative effects of mirtazapine were highly transitory, lasting a few days at most, making it a poor choice for the long-term treatment of insomnia.¹¹
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What are Some Long-term Effects of Remeron?

While Remeron has been reported as having fewer and in some cases milder adverse reactions than other types of antidepressants, reports show a fairly consistent set of symptoms common to this antidepressant, as shown below. Some short-term effects may fade over time, while others may persist, or even worsen over long periods of time. Rare and serious adverse effects are included in the list below.^1,18-26

Long-term effects of Remeron may include:

• Suicidality, most pronounced under the age of 25
• Seizures
• Physical dependence, tolerance, brain zaps on discontinuation
• Cardiac arrest
• Worsening depression
• Panic attacks
• Heart palpitations
• Vascular headache
• Increased heart rate
• Mania
• Hallucinations
• Anxiety
• Insomnia, abnormal dreams
• Increased somnolence in the elderly
• Abnormal muscle weakness (asthenia)
• Aggressiveness, hostility
• Agitation
• Twitching
• Apathy
• Impulsivity
• Amnesia
• Cough
• Sinusitis
• Akathisia
• Weight gain, increased appetite
• Anorexia
• Edema (swelling)
• Dizziness
• Liver and kidney damage
• Dry mouth
• High cholesterol
• Hypertension, cardiovascular injury
• Lowered white blood cell count, abnormally high white blood cell count
• Agranulocytosis
• Urinary tract Infection
• Other infections
• Flu syndrome
• Fever, chills, sore throat, mucous membrane ulceration, inflamed or sore mouth
• Reactions to lactose, an ingredient in Remeron
• Serotonin toxicity, NMS (neuroleptic malignant syndrome)
• SJS (Stevens-Johnson syndrome)
• SCARS (severe cutaneous adverse reactions)
• DRESS (drug reaction with eosinophilia and systemic symptoms)
• TEN (toxic epidermal necrolysis causing blistering and peeling of the skin)

IMPORTANT NOTE:  Serotonin syndrome, neuroleptic malignant syndrome, Stevens-Johnson syndrome, DRESS, eosinophilia (elevated white blood cell count), toxic epidermal necrolysis, and SCARS are rare but life-threatening drug-induced emergencies. These conditions may present at the beginning of treatment or later in the treatment phase. Immediate transport to a medical facility is essential should any signs of these conditions occur. Skin eruptions, blistering or shedding of skin, sudden fever, confusion, coma, abnormal WBC levels, difficulty breathing or speaking, and other symptoms should be carefully and alertly monitored throughout treatment with Remeron.¹⁹
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Mechanism of Action — What We Know and Don’t Know

Drug regulators and manufacturers describe the mechanism of action of any of the currently marketed antidepressants, including Remeron, as “UNKNOWN.” Research from rat and other animal studies is drawn upon to theorize what the drug may do in the human body. As an example, cat, rat, mice, and beagle studies were done on weight gain. A one-week-long study on healthy young cats found that in the treatment-with-mirtazapine group of 10 healthy young cats, considerably more food was eaten whether the dose was high or low, as compared to the 14 cats in the placebo group who were not medicated. Results, however, were not consistent over the populations of mice, rats, beagles, cats, and other animals used in the trials.^1,9,19

Psychological assessments are also used in drug trials and other treatment settings to determine changes a drug may make to a person’s mental state. Such assessments may show if a drug is improving a person’s mental state, or not, and also show if physical changes are occurring as a result of drug therapy. The “gold standard” is the Hamilton Depression Scale, a 17-point questionnaire that is filled out by the patient and/or clinical observers on a weekly basis for 4 or 8 weeks or longer.⁷ Used in a large cohort of participants, the results are tabulated and can be used to rank a drug’s effectiveness or lack thereof, or compare drugs in head-to-head trials involving multiple medications. This information is used for various purposes. For example, these results are considered when a drug goes to regulators for approval for a license before it reaches consumers. The Hamilton scale can also help a prescriber determine if one drug might be less or more effective for a particular patient, or group of patients.

The Hamilton scale ranks the presence or absence of the most common symptoms that occur with antidepressant use, such as thoughts about suicide, insomnia, fatigue, loss of interest in usual activities, physical aches and discomforts, whether time spent at work or other activities has decreased or increased, sexual symptoms, and others. Each is weighted numerically, with a higher number for more severity, and a lower number for lower severity or absence of a symptom. The frequency and duration of symptoms are also rated. While providing some observational data, such an assessment has structural limitations due to its brevity and is highly dependent on the acuity of the participant and of the observer for accuracy in reporting. It is largely a “one-size-fits-all” approach that may not be detailed enough to cover the unique characteristics of drugs or of the individuals who are taking them. For example, the scale ranks weight loss and its severity which may be relevant to a drug like Prozac but does not rank weight gain, which would be more relevant for mirtazapine. No lab tests are involved, which would be necessary for determining injury to the liver, heart, or other drug-induced complications. Another limitation is that the typically short time of observation precludes the reporting of mirtazapine’s long-term effects or those of other drugs generally.

While there have been attempts to discover mechanisms of how mirtazapine works, there is much that remains unknown.

Remeron and Pregnancy and Breastfeeding — Are There Risks?

Remeron has been designated in the US as a Class C drug in regard to pregnancy, meaning that the drug should not be prescribed unless there is a medically justifiable reason to do so. Some fetal injury was noted in animal studies and documented in post-marketing clinical reports.^19,27

The drug manufacturer cautions that the following have occurred in infants as soon as immediately after birth, and may either stem from toxic drug adverse reactions or from discontinuation syndrome in the infant:

• Respiratory distress
• Seizures
• Tremors
• Cyanosis (blue skin due to lack of oxygen)
• Hypoglycemia (low blood sugar)
• Hypotonia (decreased muscle tone from neurological damage, can be lifelong)
• Temperature instability
• Jitteriness
• Constant crying
• Irritability
• Vomiting
• Difficulty feeding
• Apnea (temporary cessation of breathing)

Based on clinical reports it has been shown that Remeron, especially when taken late in pregnancy, may also cause discontinuation symptoms in the infant, requiring long-term medical care. Remeron was not safety tested for pregnancy prior to it being marketed. Safety data for human pregnancy and breastfeeding is largely absent in the medical literature, but enough to warrant avoiding taking tetracyclic medications during and especially in the late stages of pregnancy.^17,19

Physical Dependence, Tolerance, and Remeron

Over time, dependence on Remeron may develop. Tolerance may also develop, and discontinuation syndrome may likely occur when the drug is stopped. Gradual discontinuation is recommended to avoid these harsh effects and should be supported with adjunctive therapies and adequate support for a successful recovery.

Should You Drink Alcohol While Taking Remeron?

Alcohol is a depressant, and so is mirtazapine. Taking them together can cause extraordinary drowsiness and sedation and other additive effects, and therefore should be avoided.^18,19

Long-term Effects of Remeron vs Non-pharmacological Treatment?

According to published research, less than 50% of patients treated with an antidepressant achieve remission success. and more than 50% experience one or more drug adverse reactions.^15,19

The lack of success with one drug often leads to increasing the dosage or adding other drugs to the daily regimen. Sometimes the long-term effects of Remeron (or any drug) may become impossible to tolerate. Discontinuation and switching drugs entail their own potential consequences, including those reactions associated with stopping, including brain zaps, agitation, anxiety, insomnia and others. Adverse reactions can also present when titrating a newly introduced drug, especially prevalent when an inadequate wash-out period has elapsed before introducing a new drug.

In contrast, studies have shown that evidence-based non-pharmacologic treatments for depression have equal or better results than medication-based treatment, without the liabilities of antidepressant long-term adverse effects. Evidence-based interventions for depression and other psychiatric symptoms can include CBT and other forms of talk therapy, herbal supplements such as passiflora, lavender, valerian, lemon balm, and many others (excluding St Johns Wort), and a vast range of nutritional treatments and lifestyle changes.^16,19,24,25

Recovery of Long-term Effects of Remeron at Alternative to Meds Center

At Alternative to Meds Center, we first investigate for root causes of symptoms. A lot of time and energy can be spent without relief, by blindly switching to one or another drug, and neglecting to discover what may be at the root of the problem. In contrast, we use lab testing and other assessments to reveal contributing factors that are treatable in a logical way for authentic relief.

Nutritional deficiencies can be discovered and treated with orthomolecular medicine. Safe and gentle discontinuation with medical oversight can be an important segment of the healing process, especially where long-term effects have developed. Neurotoxicity may show up on testing, and neurotoxin removal may offer true relief of symptoms. Non-drug treatments are given to assist the body in neurotransmitter rehabilitation, another essential step in the healing process.

There are many holistic, evidence-based therapies and treatments that are used in the program at Alternative to Meds Center, including safe, holistic detox, Equine therapy, exercise, Qi Gong, colon hydrotherapy, IV therapy, and many others that can be studied in greater detail on our services overview pages. We invite you to dive in and discover an amazing array of treatments available during your stay with us. Our facility is pristine, located in a beautiful location perfect for hiking, biking, photo opportunities, and many other outdoor activities. Our welcoming facility features over 50 dedicated medical and support staff, and highly popular peer support programs. Please contact us for more information about how our program may help you or a loved one regain natural mental health and recover after suffering the long-term effects of Remeron.

for Help with Remeron’s Long-Term Effects

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27. NIH Patient Information Hypotonia published online [cited 2022 Dec 1]

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Originally Published December 2, 2022 by Diane Ridaeus