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Review: Methylcobalamin side effects

In this review, we analyze Methylcobalamin side effects by the time on the drug, gender and age (0-60+) of the people who have side effects while taking Methylcobalamin. The review is based on 55 people who have side effects while taking Methylcobalamin from FDA and social media, and is updated regularly.

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What is Methylcobalamin

Methylcobalamin (latest outcomes from 63 users) has active ingredients of vitamin b12. It is often used in anaemia vitamin b12 deficiency.

It can also be called: B12, B-12, B Complex Vitamin, Bedumil, Cobamin, Cobalamin, Cyanocobalaminum, Cycobemin, Hydroxocobalaminum, Hydroxocobemine, Idrossocobalamina, Vitadurin.

On Sep, 2, 2014: 55 people who reported to have side effects when taking Methylcobalamin are studied


Most common side effects over time * :

< 1 month1 - 6 months6 - 12 months1 - 2 years2 - 5 years5 - 10 years10+ yearsnot specified
Feeling ColdAsthmaGamma-glutamyltransferase IncreasedPneumoniaCerebral Haemorrhagen/aTaste DisturbanceInterstitial Lung Disease
Visual ImpairmentVomitingTachyarrhythmiaRenal ImpairmentBlood Pressure IncreasedWhite Blood Cell Count Decreased
Altered Visual Depth PerceptionJudgement ImpairedHeart Rate DecreasedSubdural HaematomaAcne
Slow Heart BeatIrritabilityBlood Alkaline Phosphatase IncreasedWhite Blood Cell Count DecreasedPyrexia
Lip DryPartner StressBlood Lactate Dehydrogenase IncreasedMulti-organ FailureDecreased Appetite
IncontinenceAggressionBlood Pressure DecreasedGastric Ulcer HaemorrhageCough
MydriasisJudgement ImpairedDisseminated Intravascular CoagulationIleus
Abnormal BehaviourMydriasisDuodenal Ulcer HaemorrhageVomiting
Drug DependenceIrritabilityFallPruritus
Personality ChangeAggressionMalaiseLiver Disorder

Most common side effects by gender * :

VomitingInterstitial Lung Disease
Blood Pressure IncreasedPyrexia
White Blood Cell Count DecreasedAcne
Cerebral HaemorrhageWhite Blood Cell Count Decreased
PneumoniaDecreased Appetite
Skin UlcerMalaise
Subdural HaematomaIleus
Renal ImpairmentLiver Disorder
OsteoporosisPlatelet Count Decreased

Most common side effects by age * :

n/an/aGrand Mal ConvulsionConvulsionBlood Alkaline Phosphatase IncreasedPsychotic DisorderCutaneous Lupus ErythematosusInterstitial Lung Disease
VomitingLeukoencephalopathyCytomegalovirus InfectionDelusionNeutrophil Count DecreasedAcne
PyrexiaDysstasiaLarge Intestinal UlcerAbnormal DreamsAntinuclear Antibody PositiveWhite Blood Cell Count Decreased
ConstipationDysarthriaGastrointestinal InfectionSomnambulismPainDecreased Appetite
Gastrooesophageal Reflux DiseaseParaplegiaHeart Rate DecreasedAggressionSkin LesionVomiting
Weight DecreasedSpeech DisorderTachyarrhythmiaRestlessnessLymphocyte Count DecreasedCough
Gastrointestinal DisorderVisual ImpairmentBlood Pressure DecreasedOverdoseHaematocrit IncreasedMalaise
Eating DisorderNystagmusGamma-glutamyltransferase IncreasedUrinary IncontinenceErythemaPlatelet Count Decreased
White Blood Cell Count DecreasedAreflexiaBlood Lactate Dehydrogenase IncreasedAbnormal BehaviourWhite Blood Cell Count DecreasedPyrexia
ConvulsionMemory ImpairmentVisual ImpairmentHallucinationSjogren's SyndromePleural Effusion

* Some reports may have incomplete information.

Browse Methylcobalamin side effects from A to Z:

Comments for this study:

BUNNY (6 months ago):

At one point, I think you stated that cyannocobalamin(CB) is another name for methylcobalamin (MB). But read that MB is produced naturally by the body if there are normal conditions, and CB is a synthetic form of vitamin B-12.
The distinction is important: On CB, one female had rapid, pounding heart beat w/chest pain and malaise. But on MB, no side effects. Important because she has pernicious anemia and needs B-12 supplementation.
Any other experiences like this?
Reply the comment

How to use the study: print a copy of the study and bring it to your health teams to ensure drug risks and benefits are fully discussed and understood.

Are you taking Methylcobalamin?

Comments from related studies:

  • From this study (5 days ago):

  • I lost a lot of time during a 9 month period, I can't remember what I said or did. I'm being brought up on charges of writing prescription medications after my Controlled License expired. I forgot to renew it. My husband thinks that I've lost it. I couldn't remember how to do the simplest things. I thought it was my thyroid. It is enlarged but my labs came back back normal. I finally found some relief after reading an article in AARP a couple of weeks ago about drugs that can cause memory loss. I stopped taking the carvedilol right away. I'm feeling better already but I hope it clears more. I was looking for information. Many of the sites about carvedilol and memory loss are gone. It appears that there is a cover up concerning this drug. Many doctors won't admit that it can cause memory loss. The drug sites say nothing about memory loss. And a couple of sites just state that memory loss is not a side affect of carvedilol. Any help I can get would be greatly appreciated.


  • From this study (1 month ago):

  • I have continuously had the almost identical nightmare over and over again. I wake up scared, feeling like it actually happened, and I am then afraid to go back to sleep.


    sunny red on Jul, 21, 2014:

    29, male, African American... what u had was called sleep paralysis a.k.a hypnofogic sleep. Ur ur eyes and brain woke up during r.e.m sleep, but ur body remained sleeping. Very scary as the images can be seen, felt, smelled, and heard... I have it at times


  • From this study (3 months ago):

  • I was at the time of onset of health issues on a high-fat, low-carb vegan diet. Previously I had been on a no-fat, starch-based vegan diet, and in all those years never suffered any health issues, but wishing to bulk-up, switched to the high-fat approach. One day while sitting in my car reading I lost the ability to focus in on individual words. My eyes just couldn't (and still can't to a large degree) focus in on a small area. This did not occur gradually but all at once in one day. The next day, while reading a magazine in a waiting-room at a doctors office, I went completely blind in the center of my vision. I could make out forms, and shapes in the broad view, but had completely unable to make out individual areas. I was so alarmed I jumped up and immediately sped to the nearby ER, abandoning my cousin at her appointment. There the condition rapidly deteriorated, my vision further degrading to the point I thought I would be totally blind. When I went to the back, my first stop was a nurse who gave me a blood-pressure test. She said it was high. How high, I can't remember. The doctor performed an eye exam, but said he couldn't see anything wrong. He said it may be (just guessing) a diabetic issue, which was astounding to me, because at the time I consumed no carbs (far less than 100g a day), but was told that may have been inconsequential. I started taking the b12 and multivitamins AFTER symptoms developed.


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NOTE: The study is based on active ingredients and brand name. Other drugs that have the same active ingredients (e.g. generic drugs) are NOT considered.

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