Levomilnacipran XR Side Effects: What You Need to Know

Every medication comes with potential side effects, and Levomilnacipran XR (brand name Fetzima) is no exception. The good news: most side effects are mild, predictable, and often improve within the first few weeks of treatment. But some are serious enough that you need to know what to watch for.

This guide covers the common and serious side effects of Levomilnacipran XR based on FDA labeling, who may be at higher risk, and practical tips for managing them.

What Is Levomilnacipran XR?

Levomilnacipran XR is an SNRI (serotonin-norepinephrine reuptake inhibitor) approved for major depressive disorder (MDD) in adults. It works by increasing levels of both serotonin and norepinephrine in the brain, with a notably stronger effect on norepinephrine compared to other SNRIs. This unique profile gives it certain benefits — but also shapes its side effect pattern, particularly around heart rate, blood pressure, and urinary symptoms.

Common Side Effects

These are the side effects that occur most frequently in clinical trials. They're generally mild to moderate and often decrease over time:

• Nausea — The most commonly reported side effect. Usually worst during the first 1-2 weeks and improves as your body adjusts. Taking Levomilnacipran XR with food can help.
• Constipation — Affects a significant percentage of patients. Staying hydrated, eating fiber-rich foods, and staying active can help prevent it.
• Excessive sweating (hyperhidrosis) — More common than with some other antidepressants. Can happen during the day or at night.
• Increased heart rate (tachycardia) — Levomilnacipran XR's strong norepinephrine activity can increase heart rate by 5-10 beats per minute on average. Your doctor should monitor this.
• Palpitations — A feeling that your heart is racing, pounding, or fluttering. Related to the norepinephrine effect.
• Erectile dysfunction — Common in men taking SNRIs.
• Ejaculation disorder — Including delayed ejaculation. Reported more frequently with Levomilnacipran XR than with some other antidepressants.
• Decreased libido — Can affect both men and women.
• Vomiting — Less common than nausea but can occur, especially when starting the medication.
• Urinary hesitation — Difficulty starting or maintaining urine flow. This is more specific to Levomilnacipran XR's norepinephrine-dominant profile.

Serious Side Effects

These are less common but require immediate medical attention:

Suicidal Thoughts and Behavior (Boxed Warning)

Like all antidepressants, Levomilnacipran XR carries an FDA boxed warning about an increased risk of suicidal thinking and behavior in children, adolescents, and young adults (ages 18-24) during the first few months of treatment. This doesn't mean the medication causes suicidal thoughts in most people — but it means you should be closely monitored, especially early on.

Call your doctor or 988 (Suicide & Crisis Lifeline) immediately if you experience new or worsening suicidal thoughts, agitation, or unusual changes in behavior.

Serotonin Syndrome

A potentially life-threatening condition that can occur when too much serotonin builds up in the body. The risk is highest when Levomilnacipran XR is combined with other serotonergic medications. Symptoms include:

• Agitation, restlessness, confusion
• Rapid heartbeat, high blood pressure
• Dilated pupils
• Muscle twitching, stiffness, loss of coordination
• High fever, sweating, diarrhea

Seek emergency care immediately if you experience these symptoms.

Elevated Blood Pressure

Levomilnacipran XR can raise both systolic and diastolic blood pressure due to its norepinephrine activity. Your doctor should check your blood pressure before starting and regularly during treatment. If you already have high blood pressure, it needs to be well controlled before beginning this medication.

Abnormal Bleeding

SNRIs including Levomilnacipran XR can interfere with platelet function, increasing the risk of bruising and bleeding. This risk is higher if you also take NSAIDs (like ibuprofen), aspirin, or blood thinners.

Angle-Closure Glaucoma

Levomilnacipran XR can trigger an episode of angle-closure glaucoma in people with anatomically narrow angles. Symptoms include eye pain, vision changes, and swelling or redness around the eye. This requires emergency treatment.

Hyponatremia (Low Sodium)

SNRIs can cause dangerously low sodium levels, especially in older adults and people taking diuretics. Symptoms include headache, difficulty concentrating, memory problems, confusion, weakness, and unsteadiness.

Seizures

Rare but possible. People with a history of seizures should discuss the risks with their doctor before starting Levomilnacipran XR.

Mania or Hypomania

Levomilnacipran XR can trigger manic episodes in people with bipolar disorder, which is why screening for bipolar disorder is important before starting any antidepressant.

Discontinuation Syndrome

Stopping Levomilnacipran XR abruptly can cause withdrawal-like symptoms including dizziness, nausea, headache, irritability, and "brain zaps" (electric shock sensations). Never stop taking Levomilnacipran XR without your doctor's guidance. Your doctor will taper your dose gradually.

Side Effects in Specific Populations

Older Adults

Elderly patients are at higher risk for hyponatremia (low sodium) and may be more sensitive to the cardiovascular effects like increased heart rate and blood pressure. Doctors should monitor these patients more closely.

People with Kidney Problems

Levomilnacipran XR is cleared through the kidneys, so dosing adjustments are needed for patients with renal impairment. The maximum dose is 80 mg/day for moderate kidney problems and 40 mg/day for severe kidney problems.

Pregnant and Breastfeeding Women

Levomilnacipran XR should only be used during pregnancy if the potential benefit justifies the potential risk. Babies exposed to SNRIs late in pregnancy may experience complications after delivery. Discuss the risks and benefits carefully with your doctor.

How to Manage Common Side Effects

• Nausea: Take with food. Start at the lowest dose (20 mg) and increase gradually as directed.
• Constipation: Drink plenty of water, eat high-fiber foods, and stay physically active. An over-the-counter stool softener can help if needed.
• Sweating: Wear breathable fabrics, stay cool, and talk to your doctor if it's severe. Some patients find antiperspirant products designed for hyperhidrosis helpful.
• Heart rate changes: Your doctor should monitor your heart rate at regular visits. Avoid excessive caffeine, which can make this worse.
• Sexual side effects: Talk openly with your doctor. Dose adjustments or adding another medication may help. Don't stop the medication on your own.
• Urinary hesitation: Give yourself time and don't strain. If this becomes bothersome, let your doctor know — dose adjustment may help.

Most common side effects improve within 2-4 weeks. If they persist or become intolerable, your doctor can adjust your dose or discuss alternative medications.

Final Thoughts

Levomilnacipran XR is generally well-tolerated, and many patients find the side effects manageable — especially as their body adjusts over the first few weeks. The key is knowing what's normal, what's not, and when to call your doctor.

Keep all follow-up appointments, especially in the first few months. Report any new or worsening symptoms promptly. And never stop or change your dose without medical guidance.

If you're currently taking Levomilnacipran XR and need help finding it in stock or saving money on your prescription, Medfinder can help.