Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes Tambocor (Flecainide). If you are concerned about side effects, discuss the risks and benefits of Tambocor (Flecainide) with your doctor.

The following side effects have been reported by at least 1% of people taking Tambocor (Flecainide). Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• abdominal pain
• blurred vision
• Constipation
• cough
• dizziness
• Dry Mouth
• fatigue
• flushing
• headache
• muscle or joint pain
• nausea
• nervousness
• rash
• sweating
• tingling sensation
• tremor

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• new or increased symptoms of irregular heartbeat (e.g., shortness of breath, chest pain, racing or pounding heart beat, fainting, fatigue)
• symptoms of liver problems, i.e.:
• abdominal pain
• dark urine
• light-coloured stools
• nausea
• vomiting
• yellowing of the skin or eyes
• vision problems (e.g., seeing double, sensitivity to light)
• worsening symptoms of Congestive Heart Failure, e.g.:
• cough
• fast heartbeat
• fatigue
• swollen feet or ankles

Stop taking the medication and seek immediate medical attention if any of the following occur:

• chest pain
• signs of a serious allergic reaction, e.g.
• difficulty breathing
• Hives
• swelling of face or throat

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking Tambocor (Flecainide).

Do not take Tambocor (Flecainide) if you:

• are allergic to Tambocor (Flecainide) or any ingredients of the medication
• have certain types of heart problems not managed by a pacemaker (second- or third-degree atrioventricular block, or bifascicular or trifascicular bundle branch block)

Tambocor (Flecainide) should not be given to people who are in cardiogenic shock.

There may be an interaction between Tambocor (Flecainide) and any of the following:

• Abiraterone
• Alfuzosin
• amantadine
• Amiodarone
• other antiarrythmics (e.g., amiodarone, Disopyramide, procainamide, Propafenone, quinidine)
• antihistamines (e.g,. cetirizine, doxylamine, Diphenhydramine, Hydroxyzine, Loratadine)
• antipsychotics (e.g., Chlorpromazine, Clozapine, Haloperidol, Olanzapine, Quetiapine, Risperidone)
• Apomorphine
• asunaprevir
• "azole" antifungals (e.g., itraconazole, ketoconazole, Voriconazole)
• beta-blockers (e.g., Atenolol, Metoprolol, Propranolol)
• Bupropion
• Capecitabine
• carbonic anhydrase inhibitors (e.g., Acetazolamide, Brinzolamide, Dorzolamide, Topiramate)
• Carbamazepine
• Celecoxib
• Ceritinib
• chloral hydrate
• chloroquine
• Cimetidine
• Cinacalcet
• Cobicistat
• Darifenacin
• Digoxin
• Domperidone
• Dronedarone
• etravirine
• Famotidine
• Fingolimod
• formoterol
• Galantamine
• Hepatitis C antivirals (e.g., ombitasvir, paritaprevir, ritonavir, dasabuvir, )
• HIV non-nucleoside reverse transcriptase inhibitors (NNRTIs; e.g., delavirdine, efavirenz, etravirine, nevirapine)
• HIV protease inhibitors (e.g., atazanavir, indinavir, ritonavir, saquinavir)
• hydroxychloroquine
• Indapamide
• isoniazid
• Ivabradine
• lithium
• lopearamide
• macrolide antibiotics (e.g., clarithromycin, erythromycin)
• Maprotiline
• Mefloquine
• Methadone
• Metoclopramide
• Metronidazole
• mifepristone
• Mirabegron
• Octreotide
• olodaterol
• pentamidine
• Phenobarbital
• Phenytoin
• Pindolol
• Primaquine
• probucol
• protein kinase inhibitors (e.g., Dasatinib, imatinib, Nilotinib, Sunitinib)
• Romidepsin
• quinine
• quinolone antibiotics (e.g., ciprofloxacin, Norfloxacin, Ofloxacin)
• romidepsin
• salmeterol
• selective serotonin reuptake inhibitors (SSRIs; e.g., Citalopram, Fluoxetine, Paroxetine, Sertraline)
• serotonin antagonists (anti-emetic medications; e.g., Granisetron, Ondansetron)
• serotonin/norepinephrine reuptake inhibitors (SNRIs; e.g., Desvenlafaxine, Duloxetine, Venlafaxine)
• simeprevir
• sodium bicarbonate
• Solifenacin
• Sotalol
• sulfamethoxazole
• Tacrolimus
• Tamoxifen
• terbinafine
• Tetrabenazine
• Ticlopidine
• Tizanidine
• Tolterodine
• Tranylcypromine
• Trazodone
• Trimethoprim
• tricyclic antidepressants (e.g., Amitriptyline, Clomipramine, Desipramine, Trimipramine)
• Vardenafil
• vilanterol

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with Tambocor (Flecainide). Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the Nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.

Before you begin taking a medication, be sure to inform your doctor of any medical conditions or Allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should take Tambocor (Flecainide).

Abnormal heart rhythms: Certain medications used to treat abnormal heart rhythms, including Tambocor (Flecainide), may cause new abnormal heart rhythms or worsen existing ones. Your doctor will monitor you closely while you are taking Tambocor (Flecainide). If you experience a fast, slow, or irregular heartbeat; fainting; heart palpitations; or dizziness while taking Tambocor (Flecainide), contact your doctor immediately.

Drowsiness/reduced alertness: Tambocor (Flecainide) may cause blurred vision, dizziness, and fatigue. Do not drive or operate machinery until you know how Tambocor (Flecainide) affects you.

Heart failure: Tambocor (Flecainide) can cause or worsen heart failure and should not be used by people with severe or untreated heart failure. If you have heart failure and are taking Tambocor (Flecainide), your doctor will monitor you closely during treatment. If you notice shortness of breath, weight gain, or swelling in the hands, feet, or lower legs while taking Tambocor (Flecainide), contact your doctor immediately. People who have had a Heart Attack may also develop these symptoms.

Kidney function: Decreased kidney function or Kidney Disease may cause Tambocor (Flecainide) to build up in the body, causing side effects. If you have decreased kidney function, discuss with your doctor how Tambocor (Flecainide) may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Tambocor (Flecainide), and whether any special monitoring is needed.

Liver function: Decreased liver function or liver disease may cause Tambocor (Flecainide) to build up in the body, causing side effects. If you have decreased liver function, discuss with your doctor how Tambocor (Flecainide) may affect your medical condition, how your medical condition may affect the dosing and effectiveness of Tambocor (Flecainide), and whether any special monitoring is needed.

Pregnancy: Tambocor (Flecainide) should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking Tambocor (Flecainide), contact your doctor immediately.

Breast-feeding: Tambocor (Flecainide) passes into breast milk. If you are a breast-feeding mother and are taking Tambocor (Flecainide), it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of using Tambocor (Flecainide) have not been established for children.