Answer:

CoQ10 supplements are generally well-tolerated, even when taken in relatively high doses. Rarely, gastrointestinal symptoms such as nausea and diarrhea have been reported, as has mild insomnia. Piperine, which is sometimes added to CoQ10 supplements to increase bioavailability, may also cause side effects, and may interact with certain medications. For more details, plus how to minimize the occurrence of CoQ10 side effects, see the Concerns and Cautions section of the CoQ10 and Ubiquinol Supplements Review.

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17 Comments

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Jennifer18161
July 29, 2019

I experience increased fatigue when I supplement with C0Q10 at doses of 100-200 mg. My dad recently started on a higher dose (500 mg) and says he also feels more tired. I've also recently noted vision problems (trouble focusing) after restarting CoQ10 after a long break. After reading numerous comments here about vision problems, I'm going to stop it again to see if energy and vision improve.

Gigi17425
January 6, 2019

I have been taking Ubiquinol from Mercola for over a year 100mg. So far I have not noticed any side effects at all.

I am on a very low dosage of blood pressure meds. Telmisartan 40mg with Diuritic 12.5 mg. So I take BP meds in the morning, then at lunch time I have my ubiquinol and 2 garlic. The Ubiquinol has not affected my sight or my general health at all.

My goal is to try to get off my meds ASAP.

Adrian17418
January 2, 2019

I take about 800 mg a day without any side effects.

David17392
December 23, 2018

I tried several times to get on a CoQ10 regimen, starting at 100mg twice daily, but even after reducing the dose to 60mg/day, after 3 or 4 days, I would develop back aches. So I would stop taking it, the back aches would subside after a week or two and I would try again and the back aches would come back . . . again.

Rob17393
December 23, 2018

I have afib at times. I’ve been taking 60 mg of COQ10 for years. I have found if I take 60 mg of COQ10 once per day Im fine, but at 90mg of COQ10 it puts me in afib.

Martin17391
December 23, 2018

Every time I started a CoQ10 regime, I got palpitations. The first time I went into a-fib and the ER doctor didn't know what I was referring to when I told her what I was taking. I thought perhaps it was something else, like a mag deficiency (probably), but then on another occasion, it happened again. ???

Harold16941
July 4, 2018

Can some of you folks that stopped taking CoQ10 due to vision problems give us a follow up on the results. Thanks

Irene17611
March 7, 2019

I am very grateful to read the comments about some kind of relationship between eye problems and coq10. I have been taking coq10 for some time now and I was having difficulties focusing when I read or watched tv. I stopped taking any form of it, and very happy to say my eyesight has returned to normal after two days. Very grateful for this information but I would love to know why? I always believed coq10 was good for you.

Diana S16688
April 8, 2018

Interesting about the possible effect on eyesight. I've been taking Ubiquinol for years to help stop muscle pain from my statin and fibromyagia. It helps a lot with that. But recently, I've noticed trouble focusing at times. Especially on street signs or indoors at night. I've had two eye exams that find no reason for it. I'm temporarily stopping the Ubiquinol to see if the fuzzy vision goes away.

JAMES18507
October 13, 2019

You may be developing cataracts. I just completed my cataract surgery; both eyes. My eye correction before surgery had not deviated much over 5-6 years but I was having trouble focusing. It was the contrast that I was rapidly losing that presented as a loss of focus. Immediately after my first C-surgery, my eyesight was miraculously restored.

noreen16683
April 7, 2018

I have been using Vitacost ubiquinol for 6-8 months, first 50 mg per day then 2 months ago increasing to 100-200mg per day. I have noticed a significant increase in presbyopia (inability to read small print) especially in the evening (I take ubiquinol in AM). I am 48 years old and assumed that I was succumbing to need for reading glasses but have now discontinued ubiquinol and will monitor vision. I also take PQQ and am wondering if that would negatively affect my vision as well.

Deborah16678
April 5, 2018

I have been using CoQ-10 with piperine for 3-4 years for neuropathy. Switched to AM dosing several months ago after reading about insomnia. Have dry eyes and focusing issues from autoimmune condition. I thought eyes were worse in AM because of a pain med. After reading this I am going to stop it and see if that helps eyes without increasing neuropathic pain. Fingers crossed.

susana16674
April 4, 2018

I have experienced insomnia since I started COQ10, so i stopped taking it.

ConsumerLab.com
April 4, 2018
Anita16668
April 4, 2018

I, too, have been experiencing reduced ability to focus since we taking CoQ10 - to the extent that I have decided to quit taking it.

Ari16663
April 4, 2018

I have been taking CoQ10 and recently notice that I have a harder time focusing when reading small print or my iPhone and iPad. Not sure if it’s related or if I am just getting older. Curious to hear about others experience.

Lynn16661
April 4, 2018

I used to take an expensive 100 mg capsule of CoQ10 with Ubiquinol but my blood tests always indicated a low level of CoQ10. I started taking the much cheaper supplement by Kirkland -- 300 mg with NO Ubiquinol. At last. my levels were finally above normal. I am sure a high dose of Ubiquinol would have elevated my CoQ10 levels but this would have been financially impossible for me.

Merridee16649
April 1, 2018

A month after I started taking a daily 300 mg dosage of CoQ-10, I developed an itchy rash inside my elbows, neck, eventually covering my chest. Since that was the only change in my diet, I quit taking CoQ-10, and the itching and rash subsided considerably by the end of the first week. I'm now itch-free, and will not resume taking CoQ-10.

Susan 16527
March 2, 2018

When Life Extension first introduced Ubiquinol, I tried a capsule of about 8 mg. It was too powerful and caused heart problems. Never will use Ubiquinol again.

I also found that 60 mg of Ubiquinone is the most I can take per 3-4 hours. I usually take 3-4 capsules a day spread out. If I take a 100 mg capsule, I get heart pains. The wholesale clubs sell only 100 mg and up. I feel they are doing a disservice to the public. One should start lower in milligrams and work up to what they're comfortable with. Of course, for some diseases like Parkinson's, 400 mg x 3 a day Rx by M.D. may be necessary.

CAROL ANN16521
March 1, 2018

Check your other Medication That your Doctor put you on!!!!
This happen to my Mum and it was due to the Statin her Doctor put her on......
she still takes COQ10

Mary16451
February 14, 2018

I had been taking Ubiquinol which is supposed to be the easier form to take for older people. However I had to stop as I found it made me feel spaced out and affected my eyesight.

Steven16455
February 14, 2018

Same here. I stick to regular CoQ10 100mg.

Toni16517
February 28, 2018

Mary & Steven... Would you mind sharing how Ubiquinol was adversely affecting your eyesight?

Toni16519
February 28, 2018

Hi Mary,

Would you mind sharing the specific adverse effects on your eyesight that you feel may be attributed to Ubiquinol?

Mary16550
March 8, 2018

Hello
Only just read your comment. I found that about 1 hour after taking Ubiquinol my eyesight felt as if I were peering down a narrow tube and zooming in and out of the area i was looking at. It did not go out of focus. Also made me feeling slightly disorientated and unbalanced a bit like the threat of a visual migraine .
I now take Berberine with MicroPQQ whichI find really gives me 'get up and g'o.
Mary

ConsumerLab.com
March 12, 2018

Dear Mary - Thanks for sharing your experience. We have not heard before of visual disturbances with ubiquinol like the one you reported.

ConsumerLab.com
April 3, 2018

Update: Another CL member recently reported that ubiquinol seemed to affect his vision and said that reducing the dose helped. You can find his comment in the comments section for this CL Answer: https://www.consumerlab.com/answers/are-coq10-and-ubiquinol-safe-to-take-for-a-long-period-of-time/CoQ10_long_term_safety/

Bari16664
April 4, 2018

I read these comments a few weeks ago and wondered if CoQ10 could explain the fuzzy vision problems I"ve been having.
I've been taking Qunol, both liquid--previous formulation--and capsules for over a year now, maybe longer. I started really noticing this about a year ago, but because I was scheduled for cataract surgery, I assumed it was the cataracts. However, after surgery, this never changed.
I've returned for several eye exams and they say my eyes are fine and vision, too. I can't get across about this "fuzziness". It feels like it's around the edges of my eyes.
As I also have dry eyes, they attribute the fuzziness to that. Anyway, I'm stopping the Coq10 for awhile to see if that makes any difference.
Thank you for publishing these comments and for alerting us to this possiblility.

ConsumerLab.com
April 4, 2018

You're welcome Bari, and thank you for sharing your experience! Please let us know if you notice a difference.

Steven16677
April 4, 2018

I wish we could get emails alerts when someone responds to our posts.
It didn't affect my eyesight, just made me fatigued while regular CoQ 10 doesn't

JR17396
December 26, 2018

First time I've ever seen anyone comment on "visual migraine". I get them about once a month and didn't know for years what they were. Finally found a good reference on the net. It's a shimmering arc of light that slowly crosses my visual field for about 15 minutes then disappears. I just live with it, but would like to find if there is a trigger that causes it. I'm a 75 year old male.

Tom17413
December 30, 2018

I get these same visual flashing episodes about twice a month at different times of day and different places indoors and out. I've kinda ruled out stress and tiredness. It happened to me today when I was shopping at a large chain grocery store. I remembered I had the same experience at this store a few months ago. I also had this same thing happen at a Walmart store. I'm almost convinced its the overhead florescent lighting. Bright sunshine
seemed to cause it a couple of times. I do take a variety of nutrients.

Tom17414
December 30, 2018

I'm an 80 year young male . The flashing lasts about ten minutes. I also have macular degeneration that is being controlled with injections.

Dennis18508
October 13, 2019

Have you had your retinas checked?

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