How Long Does a Niacin Flush Last, and Is It Harmful?

Updated on May 30, 2019
Howard Allen profile image

Howard has had a long-time interest in health and nutrition, and has tried many vitamins and supplements over the years.

A telltale sign of niacin overdose is flushing (redness) of the skin.
A telltale sign of niacin overdose is flushing (redness) of the skin. | Source

Niacin (vitamin B3) is necessary for a variety of functions in the body, but it is most often prescribed to help patients reduce their cholesterol levels. You can also find niacin as an over-the-counter supplement at most grocery and health stores, and in foods such as brown rice, avocado, chicken breast, tuna, and turkey.

Despite its importance in the body, taking too much of it can cause unwanted side effects, the first and most noticeable one being redness and tingling of the skin, otherwise known as a niacin flush.

Below, I'll share the embarrassing story of my first niacin flush and the subsequent attempts to avoid experiencing another one.

I had been reading about all the B vitamins the night before, so the following day, while I worked (I work in a supermarket), I was thinking about all the benefits they offer, and I couldn’t wait to buy some. When it came time for my break, I bought a B complex and extra thiamine (B1) and niacin (B3). I took one of each and went back to work. Let the good health begin!

What Does a Niacin Flush Feel Like?

But something else began first. Ten minutes after taking the B supplements, I felt pins and needles in my face. Then, I felt really warm. I went to bathroom to look in the mirror. My face and neck were red, and a minute later, my arms were totally red too. I was warm and tingling all over, and my face felt slightly stiff.

I didn’t want any customers to see me as I looked like I had a bad sunburn. I tried to stay out of my supervisor’s sight, but he eventually saw me. He enquired about my health, physical and emotional, as the nature of my suffering was unclear. To cool myself down, I knew I had to go stand in the freezer, so I came up with some work I could do in there.

Niacin Function and Side Effect

Niacin is a vasodilator. It opens up the blood vessels to increase blood flow throughout the body—including the capillaries under the skin to result in the unsightly niacin flush. This is usually accompanied by a warm feeling on the skin with possible tingling and itching.

Niacin Function and Side Effect

Niacin is a vasodilator. It opens up the blood vessels to increase blood flow throughout the body—including the capillaries under the skin to result in the unsightly niacin flush. This is usually accompanied by a warm feeling on the skin with possible tingling and itching.

How Long Does a Niacin Flush Last?

The worst of the reaction lasted about an hour and a half. The all-over redness and warmth lasted the entire time. There was intermittent tingling and itching on my legs as well. I didn’t realize the reaction would be so intense and would make me look so ridiculous. Based on what I've read, it seems that the flush can last between 20 minutes and two hours, depending on the size of the dose and if it’s taken alone or with food.

I had read about niacin flushes, so I knew what was happening. If I hadn’t been aware of the side effect, I would have thought there was something seriously wrong (maybe the vitamins were poisoned or I was allergic?), and I might have gone to the hospital. Having read that niacin flushes were harmless, I waited it out.

Is Niacin Flush Dangerous?

Although it isn't dangerous, the redness, warmth, tingling, and itching can be uncomfortable. However, taking too much niacin IS dangerous, so if you experience these symptoms, talking to your doctor right away to figure out if a lower dose or alternative is necessary.

How Much Niacin Does It Take to Induce Flushing?

The daily recommended dose is around 15 mg of niacin while doses above 1500mg are prescribed to treat high cholesterol. From what I've read, 50 mg is enough to cause flushing in some people, although this might depend on the individual and how they take it. I took 500 mg of niacin on an empty stomach, which is probably why my reaction started so quickly and lasted so long.

Can You Avoid a Niacin Flush?

To avoid another horrible flush, I cut up my niacin tablets into fours so I could take about 125 mg at a time. I took one of them the next morning with food and didn’t experience any flushing. I continued taking 125 mg a few more times with no reaction.

Two days later, I bumped it up to two 125 mg doses (250 mg total). Again, no reaction.

On the third night, before bed, I went to 375 mg with food. I didn’t feel anything before falling asleep. I thought I was in the clear. However, I had a dream that I was flushing and trying to find a way to cool down.

I woke up to a niacin flush. It was three hours later. I felt this one in my dream for what felt like 10 minutes and continued to feel it after I woke up for about 20 minutes. I’m guessing this one lasted about a half hour, but I don’t know how long had been happening while I was asleep. Luckily, the intensity was nowhere near like it was the first time.

On the fourth night, I dropped down to 250 mg to avoid flushing, but, to my surprise, I experienced a flush about a half hour after taking it. The explanation seems to be this: My earlier doses of 250 mg were taken as two pieces of 125 mg taken separately with my food. This most recent dose was a single piece of 250 mg. The 375 mg dose on the third night was also one piece.

Breaking the niacin up the dose and spacing them by about a minute seems to have been enough to avoid the flush. I’m going to experiment further with how many smaller pieces I can take without flushing.

What I've Learned

Experiencing my first niacin flush was interesting and I’m glad I did. I just wish it hadn’t lasted so long and that I had been home at the time. If you plan on taking niacin as a supplement or as a prescribed treatment for high cholesterol, talk to your doctor about the possible side effects first. You may have to start with small doses to see how you react.

Another tip is to take it at home, especially on your first time. This saves you the embarrassment of being red all over, and you can just jump in a cool bath if necessary.

This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.

© 2015 Howard Allen


    0 of 8192 characters used
    Post Comment
    • Howard Allen profile imageAUTHOR

      Howard Allen 

      2 years ago


      There are lots of different bottles and brands available at supplement stores and grocery stores, and also online. I don't recommend any specific brand.

    • profile image


      2 years ago

      How does the bottle look for these supplements and where can i find them???


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)
    ClickscoThis is a data management platform studying reader behavior (Privacy Policy)