Quinidine (Injection, Intramuscular, Oral)

Quinidine can be taken in a number of different ways, there are a number of side effects that can occur, below is more detailed information on what to expect whilst taking it.


If you are suffering from an abnormal heart rhythm or malaria, then your doctor may well have prescribed you Quinidine. It is worth noting that Quinidine is only accessible via a doctor's prescription and you should not try and access it on your own. Also, though it sounds similar to the medicine Quinine, it is in fact different. The two do have some similarities, but they are used to treat different ailments.

You could have been prescribed Quinidine in a few different oral formats, including as a solution, capsule or tablet. Below you can find more information regarding typical dosages for all such forms, as well as potential side effects. Do note however that your doctor is best placed to tell you how you should be using and taking Quinidine, so if you wish to change anything after having read this, then speak to your doctor first.

Conditions Treated

Type of Medicine

  • Capsule
  • Tablet
  • Tablet with extended release
  • Solution

Side Effects

All drugs can lead to a range of different side effects, some of which are more severe than others. If you experience any of the side effects as listed directly below, then you should contact your doctor immediately.

Less common:

  • Lightheadedness or dizziness
  • Fainting
  • Yellow skin or eyes and/or abdominal pain
  • Fever
  • Delirium - ringing or noises in the ear, double and/blurred vision, visual intolerance of light, disturbed color perception, confusion, and/or a headache


  • Bleeding gums or nosebleed
  • Pale skin and/or unusual weakness or tiredness
  • Fever, muscle pain, general discomfort, chest pain, joint swelling, skin rash, and/or joint pain,

As well as those, below you can find another list of side effects which, though unpleasant, are not as serious. If you are worried about them or if they are causing you unnecessary discomfort than you can still contact your doctor. They may be able to prescribe a suitable course of action to remedy the unwanted effects.

More common:

  • Vomiting or nausea
  • Loss of appetite
  • Weakness of your muscles
  • Diarrhea

If you experience any other worrying side effects whilst taking Quinidine, then do contact your doctor for advice on how to proceed.


Below you can find the average dosages prescribed for typical patients. However, do be aware that your exact prescription could vary greatly from someone else's based on your own specific medical situation. So, even if anything below is different to what you are currently doing, you should not alter your treatment. Instead, stick to the exact guideline your doctor has given you. If you would like to make any potential changes, you must first discuss this with your doctor, and only do so under their consent.

For regular tablets (short-acting) treating abnormal heart rhythm:

  • Adults. Take 200 mg to 650 mg three to four times per day.
  • Children. Take 30 mg to 40 mg per kg of body weight per day. The doctor may well then increase the dose if necessary.

For longer lasting tablets treating abnormal heart rhythm:

  • Adults. Take 300 mg to 660 mg every eight to 12 hours.
  • Children. Take 30 mg to 40 mg per kg of body weight each day. The doctor may well then increase the dose if necessary.

For injection form treating abnormal heart rhythm:

  • Adults. Take 190mg to 380 mg every two to four hours and inject into the muscle. Or this can be up to 0.25mg per kg of body weight per minute in solution from injected into a vein.
  • Children. Your dosage will be calculated by your doctor.

For injection form treating malaria:

  • Adults. Take 10mg per kg of body weight and inject in solution form into a vein over a period of one to two hours. Afterwards, 0.02mg per kg of body weight per minute should be given. Alternatively, 24mg per kg of body weight should be injected in a solution form into a vein over a period of four hours. Eight hours after that first dose, give 12 mg per kg of body weight injected in solution form in a vein over a period of four hours, then repeat every eight hours.
  • Children. Your dosage will be calculated by your doctor.

If at any time you miss a dose, take the missed dose as soon as you remember. However, if it is almost time for you to take your next dose, then simply skip the missed dose. It is important you don't double dose. However, you should try as hard as possible to never miss a scheduled dose as this will greatly impact the treatment process.

Be sure to stick to your prescribed dosages that your doctor gave you. Do not alter from that treatment, and do not miss doses wherever possible.

If you suffer from an upset stomach after taking Quinidine, taking it on a full stomach may help lessen the effects.

If you are taking the slow-release tablet version of Quinidine, then below is some further guidance on how to take them.

  • Quinn-Release or Quinaglute Dura-Tabs. You can break these in half before swallowing. However, it is important you do not chew or crush them at all.
  • Biquin Durules or Quinidex Extentabs. You must not break, chew or crush these tablets, but instead swallow them whole. With Biquin Durules tablets, you may find that there is a whole tablet in your stool. In actual fact, this is just the casing for the medication, and the medicine itself has already been absorbed into the body.


Quinidine is known to interact with a variety of different things, including a number of different drugs. Directly below you will find a list of drugs with which it is not recommended you take simultaneously with Quinidine. It is important that you are honest with your doctor about all drugs you are currently taking, including prescription, non-prescription, supplements and any herbal remedies. Based on what you are taking, they may advise you change either one of the medications or alter the dosages to avoid unwanted interactions.

  • Ritonavir
  • Saquinavir
  • Amisulpride
  • Cisapride
  • Fingolimod
  • Fluconazole
  • Sparfloxacin
  • Piperaquine
  • Aurothioglucose
  • Itraconazole
  • Ketoconazole
  • Levomethadyl
  • Posaconazole
  • Terfenadine
  • Mesoridazine
  • Bepridil
  • Voriconazole
  • Mifepristone
  • Colchicine
  • Pimozide
  • Ziprasidone
  • Thioridazine
  • Tipranavir
  • Vernakalant
  • Dronedarone
  • Nelfinavir
  • Amifampridine
  • Grepafloxacin

Below here you will find a further list of drugs which, though it is not recommended you use alongside Quinidine, it may inevitable that you do so. Your doctor is best placed to advise you on the correct steps to take.

  • Amoxapine
  • Afatinib
  • Conivaptan
  • Acetazolamide
  • Alfuzosin
  • Amiodarone
  • Amitriptyline
  • Ciprofloxacin
  • Citalopram
  • Clarithromycin
  • Amprenavir
  • Arbutamine
  • Azithromycin
  • Anagrelide
  • Aripiprazole
  • Golimumab
  • Eluxadoline
  • Artemether
  • Asenapine
  • Astemizole
  • Dasabuvir
  • Dasatinib
  • Decamethonium
  • Atazanavir
  • Atracurium
  • Apomorphine
  • Aprindine
  • Bedaquiline
  • Blinatumomab
  • Boceprevir
  • Brexpiprazole
  • Buserelin
  • Ceritinib
  • Chloral Hydrate
  • Chloroquine
  • Clomipramine
  • Clozapine
  • Cobicistat
  • Cyclobenzaprine
  • Dabigatran Etexilate
  • Dabrafenib
  • Degarelix
  • Delamanid
  • Delavirdine
  • Desipramine
  • Deslorelin
  • Digitoxin
  • Digoxin
  • Crizotinib
  • Ajmaline
  • Alefacept
  • Donepezil
  • Doxepin
  • Doxorubicin
  • Ondansetron
  • Paliperidone
  • Doxorubicin Hydrochloride Liposome
  • Sodium Phosphate
  • Zolmitriptan
  • Zuclopenthixol
  • Droperidol
  • Efavirenz
  • Eliglustat
  • Isoflurane
  • Gemifloxacin
  • Enzalutamide
  • Erythromycin
  • Escitalopram
  • Etravirine
  • Flecainide
  • Fosamprenavir
  • Foscarnet
  • Gatifloxacin
  • Infliximab
  • Isavuconazonium Sulfate
  • Gonadorelin
  • Goserelin
  • Granisetron
  • Halothane
  • Histrelin
  • Hydroxyzine
  • Ibutilide
  • Idelalisib
  • Imipramine
  • Triptorelin
  • Sotalol
  • Lapatinib
  • Isradipine
  • Ivabradine
  • Lanreotide
  • Leuprolide
  • Levofloxacin
  • Lidocaine
  • Hydroxychloroquine
  • Lopinavir
  • Lorcainide
  • Lumacaftor
  • Lumefantrine
  • Mefloquine
  • Methadone
  • Sodium Phosphate, Dibasic
  • Mexiletine
  • Morphine
  • Morphine Sulfate Liposome
  • Moxifloxacin
  • Enflurane
  • Nebivolol
  • Nilotinib
  • Norfloxacin
  • Nortriptyline
  • Octreotide
  • Ofloxacin
  • Ombitasvir
  • Paritaprevir
  • Arsenic Trioxide
  • Nafarelin
  • Pancuronium
  • Pimavanserin
  • Vardenafil
  • Panobinostat
  • Nalidixic Acid
  • Pasireotide
  • Pazopanib
  • Pentamidine
  • Perflutren Lipid Microsphere
  • Vasopressin
  • Vecuronium
  • Vemurafenib
  • Venetoclax
  • Pirmenol
  • Pitolisant
  • Pixantrone
  • Lidoflazine
  • Hydroquinidine
  • Prilocaine
  • Probucol
  • Procainamide
  • Prochlorperazine
  • Quetiapine
  • Quinidine
  • Salmeterol
  • Secukinumab
  • Disopyramide
  • Dofetilide
  • Dolasetron
  • Propafenone
  • Protriptyline
  • Domperidone
  • Sevoflurane
  • Siltuximab
  • Sodium Phosphate, Monobasic
  • Solifenacin
  • Sorafenib
  • Trimipramine
  • Spiramycin
  • Succinylcholine
  • Vincristine Sulfate Liposome
  • Quinine
  • Telithromycin
  • Sulpiride
  • Vincristine
  • Sunitinib
  • Tacrolimus
  • Telaprevir
  • Telavancin
  • Tetrabenazine
  • Tizanidine
  • Topotecan
  • Sulfamethoxazole
  • Trazodone
  • Trifluoperazine
  • Toremifene
  • Ranolazine
  • Trimethoprim
  • Tubocurarine
  • Ulipristal
  • Vandetanib
  • Vilazodone
  • Halofantrine
  • Haloperidol
  • Vinflunine
  • Vortioxetine
  • Metronidazole
  • Simeprevir

Finally, here are some more drugs which do lead to an increased risk of a number of different side effects. However, it is often the case that they must be used alongside each other, albeit in reduced dosages.

  • Magaldrate
  • Verapamil
  • Dalfopristin
  • Amiloride
  • Tolterodine
  • Tramadol
  • Dextromethorphan
  • Abarelix
  • Galantamine
  • Dicumarol
  • Magnesium Hydroxide
  • Atenolol
  • Magnesium Trisilicate
  • Fosphenytoin
  • Magnesium Carbonate
  • Propranolol
  • Cimetidine
  • Nifedipine
  • Magnesium Oxide
  • Quinupristin
  • Nisoldipine
  • Paroxetine
  • Phenobarbital
  • Phenytoin
  • Rifapentine

Though this list of drug interactions is significant and extensive, it is not necessarily all-inclusive. You must, therefore, notify your doctor of any other drugs you are on. Similarly, if you start taking any other new drugs whilst still using Quinidine, you should notify your doctor right away as they may need to adjust your dose slightly.

As well as other medications, there are certain foods, drink and tobacco that you shouldn't consume whilst taking Quinidine. Your doctor will ask for a rundown of your diet before prescribing you this drug, you should be as accurate as possible for them to identify whether or not you can expect any interactions to occur. As with the drugs, they may need to adjust your diet slightly in order to minimise the chance of unwanted side effects from occurring.

In particular, using Quinidine with grapefruit juice is expected to cause more side effects to occur. Your doctor will advise you on whether you should cut this out of your diet entirely or not.

Finally, there is also a chance that Quinidine could interact with other medical problems you currently have. Though you should advise them on the full extent of your medical state, be extra careful to lay out any of the following, which are known to interact more severely with Quinidine.

  • A history of heart disease
  • A history of kidney disease
  • Any electrolyte disorder (Quinidine may make any heart rhythm problems worse)
  • Myasthenia gravis (Quinidine may make this worse)
  • A history of liver disease (It will take your body longer to process the removal of Quinidine, which would prolong the effects it has)


Before prescribing you Quinidine, your doctor will first need to assess whether it is a suitable drug for you to take. One key step in identifying your suitability is seeing what allergies you hold. These allergies could be in relation to foods, dyes, preservatives, animals and other drugs. Be upfront and honest with your doctor about any such allergies you have, as they may need to prescribe you a different medicine instead to avoid any unwanted side effects.

Though Quinidine is used quite widely amongst pediatric patients, there haven't been very many studies performed into how it is known to react. However, in many cases, children are able to take a higher dose than adults and experience fewer side effects as a result. Your doctor will give your child a thorough examination before deciding whether or not to prescribe Quinidine. They are most up to date with any potential risks associated with children using it.

As of writing, there have not been significant studies performed on the usefulness of Quinidine in geriatric patients. However, based on previous prescriptions, there is not necessarily a cause for concern highlighting more side effects than those experienced in children. However, one thing to note is that older patients tend to be slower at processing Quinidine out of their system, so will experience the effects of the drug for longer. For this reason, and following a thorough examination, your doctor may likely prescribe a lower dosage to be taken.

With regards to pregnant women, there have, as of writing, not been enough studies performed on the usefulness of effects of Quinidine on pregnant women. If you are worried at all that it may have an adverse effect on your or your child, then the doctor is best placed to weigh any potential risks with the side effects. If however, whilst taking Quinidine, you become pregnant, do advise your doctor straight away, as they may need to adjust your prescription.

Finally, studies performed on breastfeeding woman using Quinidine have found that the drug poses minimal risk to the child. Your doctor can best discuss this with you before prescribing the drug.

Your Doctor will likely establish some routine appointments for you to visit. These are important as they offer the chance to monitor your condition and make any necessary changes to your dosage, so be sure to attend all of them.

Under no circumstances should you stop taking your medication, unless told to do so by your doctor. If you do, then this will lessen any benefits you can expect to receive.

If you have to undergo any other form of medical treatment or dentistry whilst taking Quinidine, then make them aware beforehand that you are using it. It is possible you will experience lightheadedness or dizziness whilst taking Quinidine. It will likely occur if you sit up too quickly, so move slowly.

There is also a chance you may faint, so do not drive or do any other activity that will be dangerous if you were to faint. If you do faint, or experience any other worrying side effects whilst on Quinidine, then inform your doctor immediately.

There is the possibility your doctor will ask you to carry around a medical ID card or bracelet for the period you are taking Quinidine.


You must keep your Quinidine stored in a sealed container at room temperature. Be sure to keep it away from direct sunlight, moisture, heat as well as keeping it from freezing. Keep it away from the reach of children as it can be dangerous. Once you have finished your cycle, dispose of any remaining medication in a safe a sensible way as instructed by your doctor. Never take any medication that you can see is out-of-date.


If you are suffering from an abnormal heart rhythm, or from malaria, then by taking Quinidine you should hopefully start to see some improvement in your condition. Depending on your exact medical situation, the dosage you are prescribed may vary greatly compared to others but always stick to your exact prescription. If you were to do so, you are putting yourself at increased risk of a number of complications.

Be sure to maintain all scheduled appointments with your doctor, as these are necessary for you to discuss your treatment, and to make any suitable adjustments. If at any time you experience any of the worrying side effects as listed, you should contact your doctor immediately. If the side effects are particularly severe, then you may want to contact emergency medical assistance.


Last Reviewed:
January 31, 2018
Last Updated:
April 05, 2018