Medication Information Leaflet

What is this medication for?

This medication is used to suppress and prevent the recurrence of an abnormal heart rhythm. It works by slowing an overactive heart and correcting irregular heartbeats to a normal rhythm so that the heart works properly to pump blood.

How should I take/use this medication?

  • Do not stop taking your medication without checking with your healthcare professional.
  • You should take this medication with food.
  • Swallow the tablet whole with a full glass of water or other liquids in an upright position.
  • The doctor may adjust the dose based on your condition. Do not take this medication more often than directed and do not stop unless instructed by your doctor.

What should I do if I forget to take/use this medication?

If you forget to take a dose, take it as soon as you remember. Then take your next dose at the usual time. Do not take two doses to make up for the missed dose

What precautions should I take?

Inform your healthcare professional if:

  • You are allergic to this medication or any of the other ingredients of this medication
  • You are pregnant, planning to become pregnant, or breastfeeding.
  • You are taking any other medications, including supplements, traditional medications and herbal remedies.
  • You have kidney or liver disease.
  • You have a heart condition known as heart failure, or recently had a heart attack.
  • You have a pacemaker or defibrillator.

What are some common side-effects of this medication?

  • Dizziness and lightheadedness
    • This may occur especially when you get up quickly from lying or sitting down. Getting up slowly or changing posture slowly may help. Take a rest by sitting or lying down if you feel dizzy
  • Stomach upset, nausea or vomiting
  • Feeling nervous and excitable.
  • Changes in balance or body coordination, unsteady movement, seizures or tremors

What are some rare but serious side-effects that I need to seek medical advice immediately?

It is very important that you are on regular follow-up with your doctor to monitor for any possible side-effects. Inform your healthcare professional if you have any of the following side-effects.

This medication may worsen an existing abnormal heart rhythm, or cause new irregular heartbeats. Symptoms of abnormal heart rhythm include one or more of the following:

  • Irregular heartbeat e.g. slowed heartbeat or palpitations (having a fast heartbeat or ‘racing heart’)
  • Severe dizziness or fainting spells
  • Difficulties in breathing or chest pain

Very rarely, mexiletine may cause liver problems. These symptoms of liver injury may include dark coloured urine, light coloured stools, nausea, vomiting, loss of appetite, yellowing of skin or eyes

Mexiletine may also cause low blood cell counts in rare cases. Symptoms might include unexplained bruising or bleeding; signs of infection like fever, chills or sore throat; feeling very tired or weak.

The symptoms of a drug allergy include one or more of the following:

  • Swollen face/eyes/lips/tongue
  • Difficulty in breathing
  • Itchy skin rashes over your whole body

If you experience any of these symptoms, you should stop your medication and see your healthcare professional immediately.

What food or medication should I avoid when I take this medication?

Avoid or limit drinking alcohol to less than no more than 2 standard drinks a day for men and no more than 1 for women. Drinking too much alcohol may raise your chance of liver disease.

It is recommended to reduce your caffeine intake while on treatment with mexiletine as the medicine can increase caffeine levels in your blood.

This medication may interact with other medications. If you intend to take any over the counter medication, supplements, herbal remedy or traditional Chinese medicine, consult your doctor or healthcare professional first to confirm that it is safe to take with Mexiletine.

How should I store this medication?

Store in a cool and dry place, away from direct sunlight. Keep this medication away from children.

How should I throw away this medication safely?

Pack this medication into a black trash bag and seal it tightly before throwing it into the rubbish chute or bin.


Please take note that the above is not a complete list of all possible side effects. If you have any concerns about your medication or if you have other side effects that you think are caused by this medication, please consult your doctor or pharmacist.

If you take more than the recommended dose, please seek medical advice immediately. The information provided on this page does not replace information from your healthcare professional. Please consult your healthcare professional for more information.

This article is jointly developed by members of the National Medication Information workgroup. The workgroup consists of cluster partners (National Healthcare Group, National University Health System and SingHealth), community pharmacies (Guardian, Unity and Watsons) and Pharmaceutical Society of Singapore. The content does not reflect drug availability and supply information in pharmacies and healthcare institutions. You are advised to check with the respective institutions for such information.

Last updated on May 2023

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