Like all medicines, mirtazapine can cause side effects, although not everyone gets them. Often side effects improve as your body gets used to the new medicine.
Suicidal behaviour
The use of antidepressants has been linked with self-harm or suicidal thoughts and behaviour. Children, teenagers, young adults and people with a history of suicidal behaviour are most at risk. This is most likely during the first few weeks of starting treatment or if the dose is changed. It is important to look out for signs of suicidal behaviour such as suicidal thoughts, self-harm, worsening of low mood, agitation or aggression. If you notice any of these signs, contact your doctor immediately.
If you need urgent help or are concerned, phone:
- Lifeline 0800 543 354 (available 24/7), or
- Healthline 0800 611 116, who can give you the phone number for your local mental health crisis line.
Other side effects
Side effects |
What should I do? |
- Feeling sleepy, drowsy, dizzy or tired
|
- Be careful when driving or using tools until you know how this medicine affects you
- Do not drink alcohol
- Take your medicine at night rather than in the morning
- Tell your doctor if troublesome
|
- Increased appetite
- Weight gain
|
- These are quite common
- It may be helpful to make changes to your diet and usual exercise.
- Tell your doctor
|
- Dry mouth, feeling faint, trouble sleeping, constipation
|
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- Suicidal thoughts, thoughts of harming yourself, or worsening depression
|
- Tell your doctor immediately or ring HealthLine 0800 611 116
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- Fever, sore throat, sores in the mouth, feeling tired and unwell especially in the first 4-6 weeks of starting mirtazapine
|
- Tell your doctor immediately or ring HealthLine 0800 611 116
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- Signs of serotonin syndrome such as feeling agitated and restless, heavy sweating, shivering, fast heart rate or irregular heartbeat, headache, diarrhoea and rigid or twitching muscles
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- You are at increased risk of serotonin syndrome if you have just started taking mirtazapine or recently increased the dose, or if you are taking other medicines that interact with mirtazapine
- Tell your doctor immediately or ring HealthLine 0800 611 116
|
Read more about medicines and side effects and reporting a reaction you think might be a side effect. |