Wednesday, December 17, 2008

Overdosing on Niacin: Side Effects, Toxicity, Symptoms, Poisoning

I promised to write one column about the side effects of vitamin B1 (thiamine), vitamin B3 (niacin, niacinamide), vitamin C, and vitamin D (cholecalciferol). Deficiency in these four vitamins causes beri beri, pellagra, scurvy, and rickets respectively. I started with vitamin D because it causes the most problems. Vitamin B3 (niacin, niacinamide) is second because it is the most troublesome.

The situation with niacin is what it is. The Food and Nutrition Board has set the RDA for niacin at 20 mg/day and the upper safe limit (UL) at 35 mg/day. This is far and away the closest for the four most important nutrients. At the same time, niacin is the only vitamin embraced by mainstream medicine. It is used to treat high cholesterol. Heart doctors prescribe 2000 mg/day niacin for this purpose – more than 50 times the UL. Are we supposed to believe that some people can take 2000 mg/day with no problems and others have to both make sure that they get 20 mg/day (the RDA) without exceeding the UL of 35 mg/day? Oddly enough, the answer to this question is yes.

Niacin is famous for causing flushing. Rapid absorption of as little as 35 mg of niacin (think 35 mg of niacin with a hot coffee on an empty stomach first thing in the morning) can cause flushing. The duration and severity of flushing is proportional to the dose. A severe flush can be fearfully painful – an unforgettable experience. A mild flush could possibly be described as a pleasant experience by an unusual person – a feeling of warmth accompanied by tingling. Here is a fairly comprehensive list of other side effects listed by authorities:

Itchy feeling spots on the skin (skin looks perfectly normal upon inspection)
Dry feeling spots on the skin (skin looks perfectly normal upon inspection)
Rapid heartbeat
Low blood pressure
Liver malfunction
Tooth pain
Gum pain
Decreased Thyroid function
Blurred vision
Lazy eye

I read this information and was well aware of the side effects before I started taking niacin. The information was useful, but lacking in many important details. So, once again, from here on the story is based on my personal experience. It will take time to tell how relevant my experiences have been.

I’ve been taking niacin and reacting to niacin side effects for 12 years. Here are side effects I believe were caused by niacin that I experienced and aren’t on the list above:

Restless legs

Early on, I was taking over 1000 mg/day of niacin and feeling great. Then one day, for no obvious reason, after months supplementing near 1000 mg/day, nausea started in the morning right after I took my daily supplement. The nausea intensified throughout the morning until it became disabling. I ended up home and in bed. There, the nausea further intensified until it became agonizing. Finally, over the course of an hour or two, I vomited several times. The vomiting ended with a bright yellow fluid that I suspect is bile. When my wife was niacin poisoned, she also vomited this yellow fluid. I believe it is characteristic of the vomiting caused by niacin. One day I was taking regular doses of niacin and feeling fine, and the next day I was deathly ill. Once the vomiting was over, my recovery was astonishingly rapid. I was back to work feeling well the next day. I told my boss I had a 24-hour stomach bug. Despite great care, this happened to me two more times while taking regular doses of 500 to 1000 mg/day of niacin.

In recent years, I’ve been taking 100 to 1000 mg/day of niacin for several days in a row in short, intermittent bursts separated by weeks and months with mostly none interspersed with several days in the 60 to 125 mg/day range. When I do take it, I like to take the 60-120 mg/day dose of straight release niacin first thing in the morning with a cup of hot coffee on an empty stomach. That way I get the strongest possible reaction. I typically get a very mild flush that, to me, feels good. Less frequently I experience nothing or a severe flush. Rarely, I have experienced a 5 to 15 minute bout of intense nausea along with a severe flush.

In recent years, niacin reliably accelerates my heart rate and makes me less inhibited. I have trouble falling asleep. These effects last for about 24 hours.

On average, as the years have passed, I have been taking less and less niacin and experience a wider range of side effects at a wider range of severities. My testimony directly contradicts the common claim that niacin side effects dissipate with time. It’s not just me. I persuaded friends and family members to start taking niacin at 250 to 500 mg/day doses. Today, many of them have quit taking niacin supplements because of side effects. At the same time, I know several are taking 1000 mg/day niacin to control cholesterol and reporting no problems with side effects.

In summary, the list of niacin side effects is long. The list is so long that I recommend that anyone taking niacin stop taking it for 3 to 7 days at least once/year just to see if niacin is causing any trouble. Stopping for such a short time is not known to do any harm, and symptoms assumed to be a result of aging may actually be niacin side effects. I’ve taken 500 mg/day for several days with no side effects and have taken a single 60 mg dose that’s ruined most of a day. So, in my experience not only have I found that niacin tolerance varies widely from person to person, I’ve found that niacin tolerance in individuals varies widely. As a result, I’ve found niacin to be the hardest to use of the four vitamins associated with deficiency diseases.


At 8:09 PM, Anonymous Anonymous said...

I have been taking 2000 mg niacin for about 5 years. I have told several doctors and they do not object to this dose. However I always take Vitamin C with niacin. I usually take two doses a day: 1000 mg Niacin and 2000 mg of Vitamin C. All of my liver tests have been normal. I usually take the first dose just before going to sleep along with a glass of water. I awake in the middle of night and take the other dose along with another glass of water.

When I first took the niacin and Vitamin C, I had the classic flushing symptoms. But after a few days, it has mostly disappeared. I use to have severe hay fevers complete with allergy shots and prescription drugs. Since taking the niacin my allergy symptoms are greatly reduced and I do not take shots or prescription drugs. I still have allergy symptoms but they are greatly reduced.

If my stomach is upset at night, I do not take the niacin and Vitamin C. But this only happens a few days out of the year.

I decided to take niacin after reading about Dr Hoffer use for various diseases. Here is the link:

At 3:24 PM, Blogger Steve said...

Dear Anonymous,

Thanks for posting a comment. I'm glad that your doctors do not object to your dose of 2000 mg/day of niacin. They should not. It is the prescribed dose for controlling cholesterol.

I'm glad that you can take 2000 mg/day without side effects, and that this treatment has helped you to control your allergies.

Finally, I'm glad that you take vitamin C and niacin together.

Thanks also for the link to Dr. Hoffer's writings at Dr. Saul's website. I have studied most everything they have written, and am always on the lookout for what comes next. You can see from the website that Dr. Saul has just published two new books. I'm looking forward to reading them.

At 9:30 PM, Anonymous Anonymous said...

I would like to know what "symptons confused with aging." I have been on niacin (500-1000 mg daily) and seem to have developed neuropathy in my extremities.
Thank you,
Also anonymous

At 10:44 AM, Blogger Marine said...

I came to this blog because I've just started taking Niacin (started at 100mg/ twice a day and have increased to 200mg/twice a day) and I too have noticed such a severe decrease in my allergies that I've stopped taking my over the counter allergy medication.

Based on the cost of niacin to otc allergy medication I'll happily deal with the 30 min flush I get from the niacin (which incedently men is supposed to help stimulate hair growth).

At 9:10 PM, Blogger virginiac1963 said...

Thank you for your information. I just took my first dose of 100 mg about 45 minutes ago and the intense itching is starting to subside. I was about to jump into the cold shower to get rid of the feeling but took the dog out for a walk instead to get my mind off of it. I am to take this dose 3 times a day for 4 days and then increase every 4 days up to 500 mg 3 times a day. My mother could not tolerate niacin and I am hoping to "stick it out" as my liver enzymes were elevated with statins and cholesterol and triglycerides are way up. Your information encourages me to think that I can get through the side effects with a little patients and I will try the aspirin. Has anyone tried to use Benadryl for the itching?

At 8:17 AM, Blogger Steve said...


Thanks for stopping by with your comments. I believe most people can maintain good health without suffering any vitamin side effects. Niacin alone is not the best way to solve your problems with cholesterol and triglycerides. You should also be getting optimal doses of vitamin D (lots of sunshine), 2000 mg vitamin C per day in the morning and evening (4000 total), and 100 mg/day of thiamine in the morning and evening (200 mg/day). Since niacin is bothering you, why not use the lower dose I recommend and add in the other three?

At 8:19 PM, Blogger virginiac1963 said...

I am going to try that (vitamins C,D and thiamine)because I have now had two episodes of intense (and I mean intense) head-to-toe beet red niacin flush on 100 mg three times a day. Tomorrow I am supposed to increase to 200 mg three times a day. It is so intense that I don't know if I can take it much longer.

At 8:10 PM, Blogger Steve said...


Thanks so much for returning to share your experiences. I am very sorry that the medical profession is not more flexible. I don't know why they insist on such high doses despite side effects and then switch to 100% statins and quit niacin altogether if the high dose doesn't work out.

If the four vitamin combination doesn't get your lipid levels into the range of normal, I recommend adding a statin to the vitamins. Adding a statin drug to the vitamins will lead to further improvements if the vitamins alone are unable to get the job done. Keep on coming back to update the blog on your progress.

Thanks again,


At 10:21 PM, Blogger virginiac1963 said...

Thanks Steve for your encouragement. As it turns out, I happen to work in the medical field and I know how rigid they can be with the protocols. I wound up asking the doctor to take me off of Niacin as I could no longer handle the side effects and am now taking gemfibrozil and fish oil supplementation. I know that there are some people who have been able to lower there lipids dramatically with niacin supplementation, unfortunately I am not one of them. Good luck to all of you out there. Stay healthy!

At 1:41 PM, Blogger Steve said...

Dear Virginiac,

Thanks for stopping back. It is highly likely that the troubles you are having maintaining blood levels of important lipids within the normal range is due to a deficiency of vitamin C, vitamin D, niacin, and/or thiamine. I strongly recommend that you get all four of these vitamins. The doses I recommend for starters are at the upper limits set by the food and nutrition board. 95% of the population manages these doses without side effects. These are: 100 mg of thiamine twice per day, 2000 mg of vitamin C twice per day, 250 mg time release niacin two or three tablets per week (the time release is very important. Do not take straight release). Vitamin D should be gotten primarily from the sun. Full body exposure for just a few minutes between 11 am and 3 pm most days the sun is out works wonders.

At 11:17 PM, Anonymous Anonymous said...

How very interesting that I have ran across this blog. I was searching for information on Niacin and what effects it has on kidneys and ....well, Here I am!

My Dr. initially started me on 500mg of the -Flush Free Niacin- due to my triglycerides are high. I have taken that dosage for 3 months and returned to have my blood rechecked. My labs came back the same everything was normal except--- now my triglycerides went up higher.

It seems like I get a pain in my lower back on the right side now that my dosage of Niacin has been moved to 1000mg (I take it at night, prior to bed, per my Dr.orders) Have you ever noticed something similiar?

At 4:07 AM, Anonymous Anonymous said...

Thanks for the info. I started taking niacin (100mg), for chronic treatment resistant-depression. It is the only thing that seems to help(all other anti-d's have failed or been too intolerable), and I can't quite believe it works though my partner assures me I am dramatically different. I had played around with food/etc thinking I had got the combination right (taking it on a full stomach at lunchtime, with a glass of cold water and avoiding anything hot, and especially chilli, or red wine then stupidly I had it before I had a bath and ended up staggering to the bathroom, vomiting (the same yellow bile you mention) getting diarrorhea and passing out,whilst having incredible sweats. It was worse than my many episodes sick with stomach bugs in Thailand; so I stopped it.
Yesterday I started again, and my mood and energy improved dramatically, and if it is placebo, it's doing one hell of a job. Thanks for the info, because it sounds at this dosage I shouldn't be too concerned.


At 2:36 PM, Blogger Steve said...

Dear Anonymous,

Thanks so much for stopping by and sharing your experiences using niacin as an anti-depressant. Depression is a major problem and is difficult to treat. The nervous system depends upon vitamin C, vitamin D, niacin, and thiamine. You may want to consider adding vitamin D, vitamin C, and thiamine to the niacin you are already taking. Especially important is a form of vitamin B1 called TTFD. It's hard to find but well worth the effort.

I was especially moved by your side effect story - vomiting caused by rapid absorption of just 100 mg of niacin. This is a remarkably low dose. I totally believe it since a 100 mg dose on a cup of hot coffee and empty stomach recently had me lying on the floor moaning from the intense nausea. Happily I recovered in about 30 minutes and did not vomit.

At 8:03 AM, Anonymous Anonymous said...

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At 9:11 AM, Anonymous Christine said...

I had to laugh out loud when I read about you taking your morning dose with coffee on an empty stomach for the 'full effect'. I also do the same thing (I take 500mg of instant release niacin a day, at one time). I get a furious flush, a bit of sting and often the itch. The itch I can do without, but I live for the 'flush', the instant mood and energy boost and the occasional euphoria. I also have depression and bipolar (I think the niacin can trigger slight hypomania, which is fine by me because hypomania=I can take on the world). My triglycerides dropped 70 whole points after a couple months, my total cholesterol dropped from 250-260 range, fasting, down to 215. My LDL didn't improve an awful lot and is still high, but my HDL raised so that my HDL/LDL ratio is finally normal.

I was wondering: Is it abnormal to develop skin abnormalities from taking niacin? I have three red bumps on my left hand, about the same circumference as a cocktail drinking straw opeing. They are almost perfectly round and started out feeling like a pimple that never quite comes to a head. Now they are painless (had them from 7-10 days now), flattening and slightly shiny on top.

From what I've read about niacin, it increases blood flow to the capillaries of the skin, which is what causes the flush. Perhaps this causes the skin, an excretory organ, to flush out impurities from the body? Who knows... just a thought I'd put out there.

Thanks for sharing your experiences and many warm, glowy, happy flushes to you! xD


At 7:49 PM, Blogger Steve said...


Fantastic comments!

I hope your red bumps are gone. They are not a reported niacin side effect. If they are a side effect, they will come and go in response to niacin dosage. Please let me know if withdrawing niacin causes bumps to disappear and restarting niacin causes them to reappear.

Since you liked this column, I hope you'll read my other columns and add sunshine (vitamin D), vitamin C, and thiamine to your daily routine.

Thanks again,



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