Dofetilide (oral)

As an antiarrhythmic, Dofetilide is a very useful drug used to help return a patient's heartbeat back to a normal rhythm.


Dofetilide is a drug given to patients suffering from an irregular heartbeat as a result of atrial flutter or atrial fibrillation. This drug can help correct the heartbeat back to a normal rhythm. It works by slowing nerve impulses in the heart and is known medically as an antiarrhythmic.

You should not attempt to self-prescribe or access Dofetilide without a doctor's prescription. It has the ability to interact with a variety of other drugs and can cause side effects you should first be made aware of before taking.

Condition(s) treated

  • Irregular heartbeat

Type of medicine

  • Capsule

Side effects

As well as helping to remedy abnormal heart rhythms, Dofetilide does have the potential to cause other side effects which are unwanted. In some cases, these side effects are minor and will pass as your treatment progresses. However, in other cases, these side effects can be unpleasant and worrying. If you experience any of the side effects listed directly below it is imperative that you contact your doctor for medical assistance immediately.

More common

  • Fast heartbeat

Less common

  • Slurred speech

Below is a list of less serious side effects, which will likely pass as your treatment continues and your body adjusts to the medicine. However, if you do suffer any of the following and they are worrying you at all, then you can still contact your doctor. They may be able to adjust your dosage or advise on other ways to relieve the effects.

  • Sneezing

Though this list is extensive, it does not necessarily include all possible side effects. If what you are experiencing is not on this list, and you are concerned, then do contact your doctor for guidance.


Below you can find the average dosages given for those suffering from an abnormal heart rhythm. However, you should be aware that your dosage may vary greatly from that given below. This is because each patient is different and the doctor will base each prescription on a case-by-case basis.

This takes into account such things as the strength of the medication, how frequently you are to take it, as well as what other medical problems you suffer from. If you feel that you are not taking enough, or have any other questions regarding your dosages, then you should discuss this with your doctor.

  • Adults: Take 125 to 500 micrograms twice per day. Your doctor will then adjust the dosage as necessary.

If you miss a dose for any reason, then you should just skip this dose and carry on with your schedule as usual. It is important that you never double dose at any time. Do be aware that, to best help cure your condition, you should aim to never miss a dose, and set any necessary reminders for you to take the medicine at the right time.

Dofetilide is most beneficial when there is a consistent amount of it in your system. For this reason, you should stick to the twice regular dosage at the same time each day. It is important you do not miss a dose, and that you never take any more of it than prescribed. Doing so could have a big impact on any benefit you receive from the treatment.

When you are given your exact dosage, your doctor will require you to spend at least three days in the hospital. This is so they can closely monitor how you react to the medication and adjust the dose as necessary to find the optimal amount.

Your medicine will also come with a medication guide which you should read carefully. If you have any questions afterwards then you should address them to your doctor.

It is possible to take this drug either with or without food.


As like all drugs, it is possible that Dofetilide will interact with other medication you are currently taking. You should make your doctor fully aware of all drugs you are currently taking, including prescription, non-prescription, supplements and herbal remedies. They can make a judgment as to whether any drug interactions are likely to occur. If so, it may be that they will prescribe you an alternative form of medication, or will adjust what drugs you take. Directly below is a list of drugs with which it is not recommended you take with Dofetilide. Be clear in advising your doctor if you take, or begin to take any of them.

  • Amisulpride

Here is a list of drugs with which it is usually not recommended you take alongside Dofetilide. In some cases, however, it may be necessary for you to take both. Under such circumstances, your doctor may alter the dosage of one or both of the drugs in order to limit any interactions that may occur.

  • Promethazine

As well as drugs, there is also a chance that Dofetilide will interact with certain parts of your dietary intake. This includes what you eat, drink and smoke. Therefore, your doctor will likely require you to advise them on your typical dietary intake. This includes how often you smoke tobacco and drink alcohol. They may need to make adjustments to your diet so as to limit any unpleasant interactions with Dofetilide.

You may also find that other medical problems you currently have could interact with the Dofetilide you take. In particular, you should be clear in informing your doctor if you suffer from any of the following medical problems.

  • Heart rhythm problem (such as congenital long QT syndrome)


Before prescribing you with Dofetilide, your doctor will need to give you a full medical consultation to ensure against any unwanted effects. As a part of this consultation, they will need to understand any allergies you suffer from. You should advise them on all allergies you have, including those to this drug, other drugs, food, animals, dyes or preservatives.

As of writing, safety and efficacy have not yet been established for pediatric patients taking Dofetilide. This is because appropriate studies have not yet been performed into any effects it may have. Your doctor is best placed to weigh the potential risks with any benefits.

The appropriate studies that have so far been conducted have not highlighted any geriatric-specific problems that would make Dofetilide less useful for geriatric patients. However, older patients are more likely to suffer from kidney problems. If this applies to you then your doctor may exercise great caution and make certain adjustments to the prescription they give.

As of writing, it is unclear as to whether Dofetilide is properly safe for pregnant women to receive. There is a lack of clear studies highlighting any increased risks. Your doctor is the person most equipped to decide whether Dofetilide is a suitable drug to take. If whilst taking Dofetilide you become pregnant, then you should advise your doctor immediately as they may need to adjust your prescription.

Similarly, no appropriate studies have been conducted on women who are breastfeeding. Your doctor can discuss the medication with you and weigh any potential risks against the benefits of taking it.

Your doctor will schedule regular appointments with you whereby they can track your donation and see what effect the Dofetilide is having on your condition. They may need to make adjustments to your prescription to counter any unwanted effects or to further help treat your condition.

It is important that you do not take Dofetilide with dolutegravir, megestrol, prochlorperazine, trimethoprim, hydrochlorothiazide/triamterene, verapamil, ketoconazole, hydrochlorothiazide, trimethoprim/sulfamethoxazole or cimetidine. Doing so could lead to serious unwanted side effects.

Whilst you are taking Dofetilide, you should not drink grapefruit juice or eat grapefruit. Doing so will alter the amount of the medicine that can be properly absorbed into your body.

You should not take any other medicines unless they have first been cleared with your doctor. In particular, this includes those drugs which are potassium supplements, are salt substitutes that contain potassium, or are certain diuretics (such as triamterene, amiloride, or spironolactone).


You should store your Dofetilide capsules in a sealed container. They should never be allowed to freeze and should be kept away from direct sunlight, heat and moisture. Keep it safely away from children. You should never take medicine that is out-of-date, or that is no longer needed. If you do have any medicine that you need to dispose of, then you should do so in a safe and sensible manner as advised by your doctor.


If you suffer from an irregular heartbeat, then Dofetilide has the potential to be a very useful drug in helping to treat your condition. However, this will only be the case as long as you follow your doctor's prescription as closely as possible. They will first need to assess your condition to decide what dose is best suited to you. They will then provide you with a strict schedule of doses to take.

This schedule will ensure the medicine is evenly in your system at all times. There may be a period where you think the medicine is doing little to help. If this is the case then you can address any concerns with your doctor. Never increase or adjust your dosage unless told to do so by your doctor, as this can cause unwanted effects to occur. Similarly, if you are experiencing any of the harmful side effects listed previously, then you should inform your doctor immediately.