Propafenone for irregular heartbeats (Arythmol)

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Propafenone is used to treat irregular heartbeats. Treatment with it will be started by a heart specialist.

Take your doses just after a meal. Swallow the tablet whole with a drink of water.

Propafenone can make you feel dizzy at first. Do not drive or use tools or machines until you know how the tablets affect you.

Type of medicineAn anti-arrhythmic medicine
Used forIrregular heartbeats
Also calledArythmol®
Available asTablets

Propafenone is used to treat arrhythmias. An arrhythmia is an irregularity in your heartbeat, which causes your heart to skip a beat, beat unevenly, or beat very fast or very slowly.

Propafenone works by correcting irregular heartbeats to a normal rhythm and by slowing an overactive heart. It will be prescribed for you by a heart specialist doctor.

Some medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before you start taking propafenone it is important that your doctor knows:

  • If you have a pacemaker fitted or if you have any heart problems other than your abnormal heart rhythm. In particular, let your doctor know if you have heart failure.
  • If you have any problems with your breathing, such as asthma or lung disease.
  • If you have been told you have low blood pressure.
  • If you have a condition causing muscle weakness, called myasthenia gravis.
  • If you are pregnant or breast-feeding.
  • If you are taking or using any other medicines. This includes any medicines you are taking which are available to buy without a prescription, such as herbal and complementary medicines.
  • If you have ever had an allergic reaction to a medicine.
  • Before you start the treatment, read the manufacturer's printed information leaflet from inside the pack. It will give you more information about propafenone and will provide you with a full list of the side-effects which you may experience from taking it.
  • Your doctor will tell you what the right dose of propafenone is for you. The dose may need to be adjusted as your symptoms become controlled, so make sure you take the tablets exactly as your doctor tells you to. Propafenone is usually taken two or three times a day, after meals. Your dose will be printed on the label of the pack to remind you about what the doctor said to you.
  • Try to take your doses around the same times of day, as this will help you to remember to take them regularly.
  • The tablet should be swallowed whole with plenty of water - do not chew or crush the tablet as it has a bitter taste. Remember to take each of your doses with a snack or just after eating a meal.
  • If you forget to take a dose, take it as soon as you remember unless it is nearly time for your next dose, in which case leave out the missed dose. Do not take two doses together to make up for a forgotten dose.
  • Try to keep your regular appointments with your doctor. This is so your doctor can check your heart rhythm and monitor your progress.
  • Treatment with propafenone is usually long-term unless you experience an adverse effect. You should continue to take it unless you are advised otherwise by your doctor.
  • If you normally drink grapefruit juice regularly, please let your doctor know about this. This is because a chemical in grapefruit juice may increase the amount of propafenone in your bloodstream.
  • If you are having an operation or any medical/dental treatment, remember to tell the person carrying out the treatment that you are taking propafenone. This is because it can interfere with some local anaesthetics and increase the risk of side-effects.
  • If you buy any medicines 'over-the-counter', always check with a pharmacist that they are suitable for you to take alongside your other medicines. A medicine called cimetidine (which is taken to reduce stomach acid) can interfere with propafenone, and some antihistamine medicines are best avoided too.

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the most common ones associated with propafenone. You will find a full list in the manufacturer's information leaflet supplied with your medicine. The unwanted effects often improve as your body adjusts to the new medicine, but speak with your doctor or pharmacist if any of the following continue or become troublesome.

Very common propafenone side-effects (these affect more than 1 in 10 people)What can I do if I experience this?
Feeling dizzyIf this happens, do not drive or use tools or machines
A feeling that your heart is beating quickly (palpitations)Let your doctor know about this
Common propafenone side-effects (these affect less than 1 in 10 people)What can I do if I experience this?
Stomach upset, tummy (abdominal) painEat simple meals - avoid rich or spicy food. Make sure you take your doses after you have eaten some food
HeadacheAsk your pharmacist to recommend a suitable painkiller. If the headache continues, speak with your doctor
Dry mouth, or a bitter taste in your mouthTry chewing sugar-free gum or sucking sugar-free sweets
Chest painLet your doctor know about this
Feeling anxious, difficulties sleeping, feeling breathless, feeling weak or tired, blurred visionIf any of these become troublesome, speak with your doctor for advice
ECG changes, changes to liver function testsYour doctor will monitor for these

If you experience any other symptoms which you think may be due to propafenone, speak with your doctor or pharmacist for further advice.

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

Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine, go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.

This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.

Do not 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.

Further reading & references

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.

Original Author:
Helen Allen
Current Version:
Peer Reviewer:
Prof Cathy Jackson
Document ID:
1479 (v24)
Last Checked:
Next Review:
The Information Standard - certified member

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