Flecainide - side effects (feedback wanted)

Several folks here have mentioned the side effects they experienced while taking flecainide. Common ones seem to be dizziness or light-headedness, and fatigue. Those are the two primary symptoms I've experienced, though I have a few others as well.

My symptoms began two days after I started on flecainide 100mg 2x/day on May 8, 2015, the day after a successful ablation. Effects were so bad I quit the drug on June 13. Symptoms have continued on a near-daily basis since then.

What's most interesting about these side effects is that from the very beginning they have arisen shortly after I get up in the morning and then dissipate some variable number of hours later. I would like to know what others have experienced. Have your symptoms come on in the morning and then gone away later in the day?

This is important to me because I'm trying to find out why my symptoms continue. Something in the brain is affected by flecainide, and it displays the same pattern of activation as the release of histamine, which also happens upon waking.

I would appreciate any feedback you might have.

Thank you!


Last edited by

44 Replies

  • I take 50 mg twice a day, and the side effects seem mild but I do occasionally get a bit of dizziness. However, not sure if that is the flecenaide or just a normal experience

  • I had to stop taking the drug at 300mg twice a day.  Symptoms included severe leg pain, cold hands and feet, difficulty moving my eyes and arms. Went to hospital they stopped the drug.

    I would never consider the drug again. It was a scary couple of weeks.

  • 600mg a day - isnt the maximum dose 400 ??

  • Originally I was on 300mg three times a day .

  • nitial dose: 100 mg orally every 12 hours.

    Maintenance dose: May be increased in increments of 50 mg bid every 4 days until efficacy is achieved. Most patients with SUSTAINED VT do not require more than 150 mg every 12 hours (300 mg/day), and the maximum dose recommended is 400 mg/day.

  • I just did as was asked by consultant as I chronic AF WITH FAST VENTRICULAR RESPONSE

    I stopped using Flecanidr as I had to visit hospital the hospital due the neurologic problems

  • Loquitir, thanks for your reply.  Have you had any neurological issues since stopping flecainide?

  • The symptoms stopped after I ceased taking Flecanide and went on disopyramide.

    The leg pains are due to the AF.

  • Wow!, didn't realise it could ranked up more - I think I'd feel light headed with that much!

  • That's a heck of a lot, usually 100 - 200mg daily (taken at 12 hour intervals); 300mg is the 'pill in the pocket' rescue dose if in AF!!??

  • Koda, I took 2x50 and then 2x100 flecainide for over a year pre and post - ablation. I use 100 as a pip if necessary now. Prior to going onto flecainide they tried me on atenolol, Amiodarone, Soltalol and Tildiem. As such flecainide is the most helpful for my AF. I now take a daily 2.5 bisoprolol.

    My AF  is 98% improved since the ablation but I have a major problem with my mobility and wonder if the drugs may be responsible. My feet feel as though they are held in an iron grip. I cannot walk far without needing a rest and 20 mins gardening is enough. Following a rest I can start again. There is no pain but my legs don't work properly. Relim has recorded that she feels as though her feet are wrapped in cling film and she blames flecainide. Is this the same thing?

    I am to see an orthopaedic specialist (11 months wait) but have seen an osteopath recently. There is apparently nothing wrong with my knees and hips. So is it neurological?

    I'd be interested to know if anyone else recognises my problem.

  • Thanks for your reply.  I can't guess at what's causing your continuing problems, but if they weren't happening before flecainide, it's safe to assume the drug had something to do with it.  If I were in your shoes I'd be researching the neurological dynamics of mobility, with a particular interest in how it's affected by the central nervous system, which is what flecainide acts on.

  • Koda, I have been taking 2 x 100mg of Flecainide for nearly 2 years and have had no apparent side effects that I have been aware of - except the total absence of AF. 

    In the last month I have noticed mild dizziness which my GP thought was a recurrence of a viral inner ear infection.  However, the symptoms are different - not vertigo like inner ear but 'the staggers' and occurring only after getting up - for about an hour.  Fatigue comes and goes but I think is caused by ectopics - perhaps.

    I know it is easy to blame the drugs - especially Bisoprolol - for everything but I had decided to mention the dizziness to my EP next month.

    Thank you for starting this discussion - I am very interested in others' comments.

  • Thanks, Finvola.  My dizziness is also not like vertigo, which I've had for over 40 years.  I'd describe it as feeling like I just drank a half-pint, give or take a few ounces.  I rate staggering a level 9 on a 1-10 scale (6=weaving, 7=wobbling, 8=stumbling, 10=falling down).  I doubt highly your fatigue has to do with ectopics.  The body recovers almost immediately from missed beats.  My guess is that you and I have similar symptomatology.

    Do your symptoms show a daily cycle?  I.e., do they start after you get up in the morning and are they done some time later in the day?

    I suggest you mention your dizziness to a neurologist.  And please keep me posted.  I'm very interested in what you find out.

  • I was taking Flecanide daily for a month but had to stop as it made me feel so ill in the evening. It seemed like a severe digestion problem but I wonder now whether it was constant ectopic beats.

  • I take bisoprolol and also get the dizziness and balance problems. I have other possible reasons, damaged inner ear, and postural hypotension. 

  • Bisoprolol is a beta-blocker that keeps heart rate down.  That's what's causing your issues.  Your heart isn't pumping enough to supply your body and brain with the oxygen it needs, so you end up in a partial faint.  That happened to me while taking metoprolol.  I stopped the drug and I could function again.  Postural hypotension should resolve quickly, especially if your heart isn't artificially held down.

  • I agree, I breathe very shallow to the point where I am asked if I am holding my breath as I have my BP taken. However the oxygen level is normally about 97%. Thanks for that, it's given me more questions to ask. 

  • haha, and I thought it was just me that held my breath during BP test or ECG.

  • That's the thing though, I'm not holding my breath. I always tend to breathe that way and every now and again I gasp deeply. I've even had breathing tests but nothing was found to be wrong. 

  • deep concentration. A customer asked me when I planned to breath whilst fixing her computer. I just laughed, at least I did not have my tongue out at the time.

  • I take  One 50mg flecainide tablet three times a day ie one every 8 hours.  I experience all of your symptoms but because I also take 25mg atenolol and a blood pressure tablet Felidopine I think it is the combination of all my meds? I am not sure whether it is just the flecainide or the drug combination? I am fed up of feeling dizzy etc though.

  • I take 2*50mg of Flec and cannot take ANY dose of beta blocker without me feeling appalling - I have no side effects on the Flec on its own.

  • I know what you mean unfortunately my meds are the only things in combination that control the AF. 

  • Isn't Flec supposed to be taken with a beta blocker or something similar?  Flec on its own not recommended?  Not sure...

  • have heard that but my cardio quite happy with me taking this +losartan for BP .

  • "Like" really means "unlike."  It's awful, isn't it?  Please tell me, do your symptoms show a daily cycle? I.e., do they start after you get up in the morning and are they done some time later in the day?  If so, you and I may have a similar problem.

    I suggest you look up flecainide on drugs.com and look for interactions with the other meds you're on.  Some other drugs, like diltiazem, increase the amount of serum flecainide, and it can be mutual.

  • My symptoms vary from day to day.  I have good days and bad ptdays.  I find if I am very tired then the syptoms are worse.  The Cardiologist says my meds are the right combination for my particular AF which I have had for 13 years. I have regular reviews of my meds.  My pulse is always quite slow at around 45 and sometimes lower.

  • Please advise, is flecanide used in the UK? I am only on bisoprolol 10mg and not been offered anything else. Maybe it's because of my other medications of which there are quite a few. Thanks. 

  • I take 2*50mg daily - no side effects , but if I up dose to 200 get dizzyspells and feeling woozy been on Flec for 6 years having reduced the doses to the present level.

  • dmac how did you manage the reduction from the higher dose?  When I tried to go down to 50/100 then 50/50 I had such severe PVC's and felt so awful that My EP said to go back up again.

  • exercise and trial and error

  • Do your symptoms show a daily cycle? I.e., do they start after you get up in the morning and are they done some time later in the day?

  • Yes , almost always when I am out walking and try to go uphill.

  • I was on 100mg twice a day and got bad headaches breathless and not feeling at all well but after lunch for two hours OK. I cut down to 50mg i  the morning and 100mg at night and this suited me alot more and i was also given amitripyline a small dose at night to help the headaches. Everything went well but now I am back in AF and will have to think about how to take an increase dose.

  • I could not take Flec it stopped my heart and caused me to have a pacemaker.  I have taken Sotalol for 5 years.  The episodes of Afib came back after 2 years on the drug, suffered 9 hospital stays then had an ablation last May. A cyroablation.  No Afib but when I tried to get off of it the heartbeats went and stayed well over 100.  Have to be on it 

  • I take 50mg of Flec twice a day and 20 mg of Nadolol once a day.  First 3 days I was okay but on the fourth day I started getting dizzy at around noon.   I was sitting then and when I got up I passed out and went to the floor.   I was able to get up immediately but felt dizzy and  nauseous for about 2 more hours.  Day 5 - the same dizziness and nausea.   It is 10 days later now and I am not feeling dizzy or nauseous.  The pharmacist did caution me about possibly  feeling dizzy and passing out within the first few days when taking Flec until the body adjusts to it.  The Flec seems to be helping with the AFIb.

  • As well as the common ones you mention i also have nystagmus when looking into bright light and especially when looking to the side without moving my head. All of these are worse in the morning but I have another which is only obvious when coming from dark to light at night. I can see multiples of whatever Im looking at in my peripheral vision eg lots of doorframes,window frames,llines round the outside of the t.v. picture frames etc . However it doesnt happen going from light to dark. When I came off flecanide to see if my ablation had worked, all the symptoms disappeared. 

    Hope this is helpful.

  • I had the same thing while on flecanide, auditory hallucinations....scared the heck out if me. This was after my ablation when they increased it to 300mg from 200mg...after one week of it I decreased it and then stopped altogether after being terribly sick for month taking it post ablation to point of not being able to eat.  I was also taking the calcium channel blocker which I read even increases the serum level of both dugs when combined.  Awful.

  • Had some visual disturbance, but stopped when discontinued daily use.

  • I take 300 mgs daily and don't feel very well. Flecanaide is the only drug I take. I feel dizzy, pain in eyes and lots of pain in my legs and feet. I scheduled a consultation with a Neurologist to get his opinion. In the meantime, I have filled a prescription for Pradaxa and will start taking Flecanaide as PIP. This was my decision and my EP has gone along with it. I have been told my EP that when I stop taking the daily dosage I will experience lots of palpitations. At this point, as long as I'm protected from stroke I would rather experience symptoms that the horrible side effects of Flecanaide. I will let you know if the symptoms of the medication go away. Gracey 

  • Gracey, thanks for sharing.  You might want to look into the relationship between microglia and neuropathy.  Flecainide suppresses microglial cells, the brain's primary immune system.  With the immune cells disabled you can have all sorts of problems.  I hope that isn't the case.  I feel as you do, I'd rather have arrhythmias than this cursed autoimmune disorder.

    Please share your experience with the neurologist.

  • Kodaska, I see Neurologist on May 5 and will share what hesays. I don't have much faith that I will get the answers but will keep searching. Will go off the Flecanaide and see if there are any improvements. Keep you posted! Gracey 

  • I get numerous symptoms associated with my head/consciousness, viz:

    A feeling of pressure in my head like you get when you hang upside down or have a ligature around your neck.

    A feeling similar to drunkenness: difficulty focusing my mind, thinking, concentrating, handwriting comes out as a scrawl, typing slow and full of errors.

    Partial paralysis of my fingers when I got in from a bike ride and couldn't write my name on a registration form at a reception desk.

    Arms feeling so heavy and leaden that it takes an extreme level of exertion to lift them to wash my hair in the shower.

    Low blood pressure feeling, with the lights dimming.

    Feeling nauseous when I watch moving objects on the TV.

    Ocular migraines.

    Tingling in my tongue similar to a dental anaesthetic wearing off, or touching the terminals of a battery.

    They all get worse when I resume training, and abate when I quit, but they were all present long before I started the meds (Flecainide and Diltiazem). I can mitigate the drunk feeling by eating more, but at the expense of gaining weight.

You may also like...