CoQ10 Side Effects

There’s a lot of info on this site about the powerful antioxidant CoQ10, but I’ve gotten some questions concerning CoQ10 side effects and if there’s anything to worry about.  The short answer is, not really.  But let me go into detail for you.

As a quick reminder, Co Q10 is a vital substance created by the body and supplemented by the diet that is used in energy metabolism and as anitoxidant protection, particularly in the energy generators of the cells (called the mitochondria).  It’s especially important for those taking cholesterol-lowering statin drugs (which deplete the body of CoQ10- more on this topic in this article on CoQ10 and statins), but is also taken by athletes, for anti-aging purposes, and for overall health.  Some other promising areas of CoQ10 use are in cancer (to reduce the side effects of chemotherapy) and to reduce the symptoms of heart failure.

CoQ10 Side Effects

Okay, that’s all great, but can it hurt you?  Again, the short answer is no.  This is a substance that is created by the body, so in and of inself, it is obviously non-toxic.  At typical doses (30 to 200 mg/day), side effects are very rare.  There’s some report of insomnia for those taking over 100 mg/day, but I’ve never seen it or even heard any such report from any other practictioner using CoQ10.  In other words, really rare… so rare that I wonder if there isn’t a confounding variable involved other than CoQ10 on these reports.

There’s unclear evidence concerning increased liver enzymes with very high (300+ mg/day) doses of CoQ10.  Not full-blown liver disease, just elevated liver enzymes.  Again, the evidence on this is so weak and contradictory that I strongly discount it.

What is uncommon, but occasionally reported are mild complaints like heartburn and nausea, which are most likely attributable to the quality of the product itself.  If you buy junk CoQ10 from a manufacturer with poor quality control, you may get a product that has impurities in it as a result of those poor manufacturing guidelines.  Look for reputable manufacturers who adhere to GMP (Good Manufacturing Practices) guidelines, and remember that you get what you pay for.

The only real side effects of CoQ10 that I think you need to worry about are those in which Co Q10 reacts or interferes with a medication you may be taking.  The big ones to pay attention to here are Warfarin (Coumadin) and insulin.  Specifically, CoQ10 may reduce the effects of Coumadin (a blood thinner), and reduce the need for insulin by diabetics.

Notice that the second of those two “side effects” is actually a benefit!  But, if taking CoQ10 does improve your diabetic symptoms, then your current level of medication may actually end up being more than you now require, so if you are diabetic and you begin taking CoQ10, just be sure to keep your doctor aware of this and monitor your blood sugar levels in case you need to adjust your insulin dosage.  Again, I call this a good thing, because the less medication you need to take, the better!

One more side effect that rarely reported is dizziness.  This is probably due to the fact that CoQ10 lowers blood pressure in some people, so if you already have low blood pressure and are looking to start taking CoQ10, I’d start off with a low dosage (30 mg/day) and work your way up after a few weeks at that level just to be on the safe side.

On an overall note about Coq10 side effects, I will tell you from an individual perspective that I have never encountered any of these side effects or even had another practitioner mention any of these side effects from their practice.  In other words, the incidence of any of these effects are extremely rare.  However, it never hurts to be informed.

My recommendation is, make sure you buy a quality product and take it with a fat-containing meal (since CoQ10 is fat soluble), and you’ll avoid any unlikely nausea or heartburn.  If you take one of the medications listed above, be sure to keep your doctor informed that you are going to start taking CoQ10 and that you want to monitor your medication levels if necessary.

More on the benefits of CoQ10 here.

Stay healthy!