3. Mirtazapine

Mirtazapine

  • It may take four weeks before you feel better although you may feel some improvement earlier than this.
  • You may find it helpful to tell a relative or close friend that you are depressed. Tell someone straight away if you are having thoughts about harming yourself.
  • You must keep your regular appointments with your doctor who will monitor your progress.
  • Mirtazapine can cause drowsiness and light-headedness.
  • Do not stop taking mirtazapine without speaking to your doctor first as this may cause problems.
Type of medicine Antidepressant
Used for Depression in adults
Also called Zispin SolTab®
Available as Tablets, orodispersible (melt-in-the-mouth) tablets, oral solution

Noradrenaline and serotonin are chemicals in the brain which, when released, act to improve mood. Depression is thought to involve a decrease in the amount of these chemicals. Mirtazapine works in the brain to increase the amount of noradrenaline and serotonin in order to lift mood and help relieve depression.

Before taking mirtazapine make sure your doctor or pharmacist knows:

  • If you have liver, heart or kidney problems.
  • If you have hypotension (low blood pressure), glaucoma or diabetes.
  • If you have ever had epilepsy.
  • If you have been experiencing difficulty passing urine.
  • If you have a history of psychiatric disorders such as schizophrenia or bipolar depression.
  • If you have an intolerance to sucrose or have a condition called phenylketonuria.
  • If you are pregnant, trying for a baby or breast-feeding.
  • If you are taking other medicines, including those available to buy without a prescription, herbal or complementary medicines.
  • If you have ever had an allergic reaction to this or any other medicine.
  • Before beginning treatment, read the manufacturer's printed information leaflet.
  • Take mirtazapine exactly as directed by your doctor.
  • Tablets should be swallowed whole with a glass of water. Do not not chew or crush the tablets.
  • Orodispersible (melt-in-the-mouth) tablets should be removed carefully from the packaging by peeling off the foil then placed on the tongue where they will dissolve. They can then be swallowed without water.
  • Try to take mirtazapine at the same times each day to avoid missing any doses. It is usually taken at bedtime.
  • If you forget to take a dose, do not worry, just remember to take the next dose when it is due. Do not take two doses together to make up for a missed dose.
  • It may take up to four weeks before you feel the full benefit of this treatment although some improvement is often felt earlier than this. Do not stop taking mirtazapine thinking that it is not working.
  • Suicidal thoughts may be associated with depression and the medicines used to treat it. You may be at risk of such thoughts early in your treatment, or soon after stopping if you have previously thought about harming yourself, or if you are a young adult. Tell your doctor straight away if you are having any thoughts of harming yourself.
  • You must keep your regular appointments with your doctor who will want to check on your progress. If you do not feel any better after taking mirtazapine for 4 weeks, let your doctor know.
  • Mirtazapine should usually be stopped gradually over a few weeks to avoid withdrawal symptoms which may include dizziness, anxiety, headache, feeling sick and agitation. For this reason, do not stop taking mirtazapine without speaking to your doctor first.

Along with their useful effects, all medicines can cause unwanted side-effects although not everyone experiences them. These usually improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following side-effects continue or become troublesome.

Mirtazapine side-effects What can I do if I experience this
Drowsiness Make sure your reactions are normal before driving, operating machinery or doing any other jobs which could be dangerous if you were not fully alert. Try to avoid alcohol as it will increase drowsiness
Light-headedness or dizziness when getting up from a sitting or lying position Getting up slowly should help. If you begin to feel dizzy, lie down until the feeling passes, then sit for a few minutes before standing. If this becomes a problem speak with your doctor
Increased appetite and weight, dry mouth, swollen feet and ankles, tiredness, shakiness, vivid dreams or difficulty sleeping, agitation, pain in the joints or muscles, and feelings of hostility such as anger If any of these become troublesome, speak with your doctor

Important: if you develop any of the following, contact your doctor straight away:

  • Jaundice (yellowing of the skin and whites of the eyes).
  • Fever, sore throat, or a swollen and sore mouth.
  • Swelling of the lips, face or tongue.

If you experience these or any other worrying symptoms which you think may be due to this medicine, discuss them with your doctor or pharmacist.

  • Keep all medicines out of the reach and sight of children.
  • Store in a cool, dry place, away from direct heat and light.

  • Keep all medicines out of the sight and reach of children.
  • Make sure that the person prescribing this medicine knows about any other medicines that you are taking. This includes medicines you buy and herbal and homeopathic medicines.
  • If you buy any medicines check with a pharmacist that they are safe to take with your other medicines.
  • Before taking this medicine tell your doctor if you have ever had an allergic reaction after taking any medicine.
  • Never take more than the prescribed dose. If you suspect that you or someone else has taken an overdose of this medicine go to the accident and emergency department of your local hospital at once. Take the container with you, even if it is empty.
  • If you are having any treatment like an operation or dental treatment tell the person carrying out the treatment which medicines you are taking.
  • Always read the printed information leaflet that comes with your medicine.
  • This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.
  • Never keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.
  • If you have any questions about this medicine ask your pharmacist.
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Further reading & references

  • British National Formulary; 59th Edition (March 2010) British Medical Association and Royal Pharmaceutical Society of Great Britain, London.
  • Manufacturer's PIL, Mirtazapine 15 mg and 45 mg Tablets, Actavis UK Ltd, electronic Medicines Compendium. Dated October 2010.
  • Manufacturer's PIL, Zispin SolTab®; Manufacturer's PIL, Zispin SolTab®, Organon Laboratories Limited, electronic Medicines Compendium. Dated October 2010.
Original Author: Helen Allen Current Version: Peer Reviewer: Prof Cathy Jackson
Last Checked: 15/12/2011 Document ID: 1081  Version: 24 © EMIS

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

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