Mirtazapine (Remeron): sleep, appetite and side effects

By the Medsmingle Team · Updated 13 November 2026

This is a prescription medicine. Only take it if it has been prescribed for you after a medical assessment, and follow your doctor’s and pharmacist’s instructions.

Mirtazapine (Remeron) is an antidepressant taken once a day at bedtime. It’s often chosen for people with depression who also have poor sleep or poor appetite.

Why it helps sleep and appetite

It blocks histamine receptors, causing drowsiness, and increases appetite. Sedation varies between people and doses. Do not change the dose to manage sleepiness without medical advice.

Side effects

• Drowsiness, especially in the first weeks
• Increased appetite and weight gain
• Dry mouth, constipation
• Dizziness

Rare but important

Mirtazapine can rarely lower white blood cells. Call your doctor for fever, sore throat, mouth sores or other signs of infection.

Important safety information

• Don’t stop suddenly; your doctor will taper the dose to avoid discontinuation symptoms
• Suicidal thoughts: Antidepressants carry a warning about suicidal thoughts or behavior in children, adolescents and young adults, especially early in treatment or after dose changes. Seek urgent medical advice for new or worsening symptoms and emergency help for immediate danger.
• Serotonin syndrome (rare): agitation, fever, fast heartbeat, muscle twitching. Get urgent help

Interactions

• Alcohol and other sedatives
• Other antidepressants, tramadol, triptans

Frequently asked questions

Is mirtazapine less likely to cause sexual side effects?

Yes, compared with SSRIs, sexual side effects are less common.

For questions about a prescription or symptoms, speak with your own doctor or pharmacist. For website enquiries, contact our team.

General information only. It isn’t a substitute for advice from your doctor or pharmacist.

Source

MedlinePlus patient medicine information. This overview does not list every warning or interaction.