Sweet Pains: Headaches, Fatigue and Brain Fog

In 2008 I started having bouts of fatigue and brain fog. The brain fog became so bad that I stopped reading and writing. I simply couldn’t maintain my thoughts from paragraph to paragraph. Sometimes I’d feel better for a while, but it never lasted.

The fatigue increased over the years, along with body aches and back pains. After a few years of this I started getting full-on dizzy spells. A few times on work gigs I felt so groggy and out-of-it I feared my clients would think I was stoned.

From the start I thought it was digestive. At the same time the brain fog started the Lactase enzyme pills I took to avoid headaches when I consumed uncultured dairy stopped working. My digestion had become very sluggish. I would often get a sharp stabbing pain just under my right ribs.

I went to the doctor and explained that it felt like I had the flu without the fever, or like I was intoxicated.  At my request, he sent me to a gastroenterologist. The man knocked me out and did the old tube inspections from above and below and declared it was not a digestive issue. Move on boy. Stop bothering me with your imagined digestive problems. I looked at the surface of your emptied guts and it all looks fine to me, so your symptoms must be in your mind. By the way, there’s no such thing as food intolerance. There’s no such thing as gluten intolerance., that’s all just mass hysteria, including all the science behind it. Lactose intolerance can’t cause headaches, so that’s also psychosomatic. Stomach aches, the sluggish digestion, the fatigue and headaches? All psychosomatic.

My primary physician retired soon after all this started. He handed his practice over to another doctor. After a year or so with the new guy, I decided his temperament just wasn’t a good match for me. I found myself another new primary physician. Over those years all three doctors said my blood tests showed I was healthy. All three stated that lactose intolerance didn’t cause headaches, so the headaches must have been tension headaches, even though I got them only when I ate dairy. I was frequently grilled about drug and alcohol use, and then ironically would be prescribed addictive narcotics as pain relievers. All three said I was perfectly healthy and my symptoms were psychosomatic.

With the new doctor I asked to see a different gastroenterologist. The moment I sat down with this new guy, without any real discussion, as he spent the entire time on the phone discussing another case, the doctor said I was fine and my symptoms were psychosomatic and to go home. Apparently there were notes in my medical record from the previous gastroenterologist, so I was on my own.

In the middle of December of 2011 things took a turn for the worse. I started having fairly non-stop intense headaches. The grogginess increased. The brain fog doubled. I felt jittery and anxious. It was my prior symptoms multiplied by ten. Luckily I was about to have a breakthrough.

A few week after the headaches started I developed a numbness in my right foot. I went to a podiatrist first. He said this symptom was typically found in alcoholics. I went to my primary physician. He once again prescribed narcotics to calm my nerves, as the gastroenterologist had informed him the symptoms were psychosomatic. I talk to a neurologist just in case, who said it sounded like alcoholism or toxic neuropathy. The fatigue and joint pains increased.

After six weeks of nearly daily headaches and other body pains I started a Pain Log. Every day I wrote down a short description of all the pain I was in along with trying to define how bad it felt. By the end of a month every day had some notes. Doing this helped me focus on each day: how stressed I felt, what I was eating, what the weather was like, etc. The hope was that something would jump out as a trigger. While snacking on a square of chocolate, I suddenly had a realization. It got so much worse in December. I’d ordered a big batch of these chocolate bars off Amazon at the beginning of December. I’d been having little pieces fairly regularly. I bought them because I was keeping low sugar to keep my triglycerides down. They were milk free, gluten-free, 70% dark, and sweetened with Stevia. They should have been innocuous. I examined the ingredients more closely, only to realize these bars had not been sweetened with Stevia like it claimed on the front, but instead were primarily sweetened with Erythritol and Inulin. Only the very last ingredient was a highly processed ingredient derived from Stevia.

Erythritol is a fermented corn sugar. The body cannot digest it, so it is sold as a low calorie sweetener. I get headaches from Lactose, why not another indigestible sugar? Inulin FOS is a prebiotic. It’s purpose is to feed the bacteria in your gut.

I stopped snacking on those chocolate bars. The headaches stopped and have not returned. I did some research and found that undigested sweeteners pass through the colon, often feeding all the bacteria that naturally exists there. Toss in a prebiotic substance like Inolin and you’re just asking for trouble.

That’s when I had my second realization. Back in 2008 my wife had brought home a new sweetener that was marketed as “Stevia without the bitterness” called Truvia. For four years I’d been using it just in my coffee. I’d commented to my wife many times that I often felt a bit off by my second cup of coffee, both decaf and caffeinated, and wondered if I had a mild coffee tolerance issue. Since my wife “needed” her coffee each morning, and it always smelled so good, I continued to drink just one cup most mornings.

The ingredients in Truvia were not listed on the sugar packets themselves, so I looked them up on the Internet. It turns out Truvia is also mainly Erythritol with a tiny amount of highly processed Stevia, just like those chocolate bars. I stopped using Tuvia. The fatigue and dizzy spells are gone. The lactase enzyme pills work again. I’m reading for enjoyment again. I’m writing again. I’m more alert and focused than I’ve felt in years. It appears that putting that tiny amount of low calorie sweetener in my coffee on occasion had been messing me up.

Looking at the symptoms, my guess is that the undigested sugar was overfeeding either yeast or bacteria in the gut, thus causing a natural fermentation. This would explain the feeling of intoxication, along with having physical ailments typically found in an alcoholic. All I truly know is the symptoms are gone.

As of today I still have some numbness in my right foot. The neurologist said it might take up to a year for the nerves to heal after toxic neuropathy. Luckily, it’s not crippling, just mildly annoying. Otherwise, I’m doing much better.

The other week my wife handed me one of her women’s magazines, pointing out an article called “I fought fatigue – and won!” It was about a woman that had a similar experience with Sucralose, noting that a recent study by Duke University found that Sucralose decreased total intestinal bacteria and slashed the number of beneficial bugs by up to 67 percent, thus worsening gastrointestinal symptoms. This had caused the woman to experience brain fog and fatigue.

This got me to wondering how many other people are having similar symptoms from the many new sweeteners that have been added to our diets over the past thirty years. My wife and I also both react very badly to aspartame. She gets migraines from it.

So, if you decide to try the low carb and no sugar diet I suggested in my post about triglycerides and cholesterol, I’d personally recommend being careful of all those low-cal artificial sweeteners. Artificial sweeteners like saccharin have been scientifically linked to weight gain anyway.

The knowledge I’ve gained about various forms of sweeteners over the years has proven that it’s also not as simple as only using natural sweeteners instead of synthetic. Each of us has a tolerance level for each of the various forms of sugar, in both high and low glycemic forms. This tolerance also changes with age. Some natural sugars, including agave and honey, which are too often marketed as healthy, can be just as problematic as synthetic sweeteners for a large percentage of the population. I’ll discuss this topic in the near future.


  1. I do wish we’d known this about saccharine when I was drinking Tab by the gallon ;o) There are so many chemicals out there that it’s scary!

    But I’m glad you’ve found your culprit!

  2. Glad you were able to figure this out! And thanks for posting about it, it’s really useful info.

  3. Holly

    Thank you so much for posting this! I too am experiencing these awful symptoms and all my lab work says I am the picture of health. I work out and eat right, concerned about how bad sugar is, I have been using Truvia!!!!! I am going to stop immediately and see if I notice a difference. I only use Truvia in my 2 cups of coffee each day, if I am in fact sensitive to whatever is in this, is there any thing else I should avoid? You mentioned milk???

    • Al Bogdan

      Watch out for any sugar alcohols. Those would be any sweeteners that end in -ol, like malitol, sorbitol, etc. If you are reacting to erythritol you might react to those as well. They are all hard to digest, which is why they are low calorie.

      I find that I don’t appear to react to pure Stevia, but as I understand it the Stevia plant is related to ragweed. I know someone with asthma that reacts badly to it because it triggers her allergies.

      The majority of adults react to lactose to some degree. Lactose is milk sugar. So, it’s always a good idea to watch for reactions to dairy. If you are reacting to lactose you might be able to eat hard cheese and possibly yogurt, but react to non-fermented milk products. That’s because the fermentation process that creates hard cheese and yogurt eats most of the lactose sugar.

      If cutting those don’t help, you might want to investigate your fructose absorption versus glucose, as discussed here:
      Who has Heard of Fructose Malabsorption?

      I don’t react to Sweet ‘n Low, but it’s such a “chemical” sweetener that I don’t like the idea of using it.

      Oddly, my immune system reacts badly to cane sugar, but not beet sugar. Luckily I live in the US Midwest where beet sugar is made, so it’s readily available.

      I just signed up for the uBiome Microbe Sequencing Project which should be interested. I’ll report back on it.

  4. Katy Hayes

    Thank you so much for posting this! I have chronic Lyme Disease, and as part of my treatment, I have cut way back on my sugar consumption. I found some great sugar-free chocolate that contains erythritol and oligofructose (billed as ‘a prebiotic fiber’). It took me until two days ago to realize that the return of brain fog, short-term memory issues, anxiety, muscle fatigue, general fatigue, and aches and pains might be related to eating this chocolate. Thank goodness I put the pieces together; I am already feeling better after just 48 hours without eating any of this chocolate. Your description of your symptoms confirms that I am not dealing with a return of Lyme symptoms, but with a reaction to the erythritol and oligofructose.

    • Al Bogdan

      Glad you figured it out!

  5. Maz

    I’ve been through exactly the same for seven years, being a couple of them a total nightmare (not being able to work). I finally did the low fodmap diet which helped, among other things I discovered that inulin acts a a real poison in my body. BTW I’ve always had lactose intolerance. Finally the only way I got (I am getting) better was by cutting ALL sugars including alcohol and grains. I still have occasionally the cat purring on my right foot as I call it…. The scd 24h yogurt works amazing to improve the sluggish digestion.

    Good luck to all of us in the same boat!

  6. Tom

    I Googled “erythritol sleepy” and ended up here. Lately I’ve been feeling brain foggish and sleepy, even after coffee, and I’ve been puzzled by it. I realized that lately I’ve been enjoying chocolate chips made with Stevia and Erythritol. I’m beginning to think that, in my own body at least, there’s a connection between Erythritol and feeling sleepy or groggy. I’m a 62 yr old male in otherwise good health. So I will stop consuming that chocolate.

    • Al Bogdan

      Back when I was consuming erythritol I felt as if I was always inebriated. I wondered if it was fermenting in the gut. Hopefully cutting out the chocolate does the trick.

  7. Holli

    I’m so glad I ran into this. I’ve been eating Lillys chocolate. “Stevia sweetened.” Same thing on the ingredients, inulin and erythritol. I’m so sluggish today from the chocolate I ate yesterday.

    • Al Bogdan

      Glad to have helped.

      It’s a shame, as I’ve tried real Stevia and didn’t have any bad reactions. Seems to be the sugar alcohol, erythritol, that causes the problems. All the so-called “stevia” products must be using Truvia instead of Stevia.

  8. Asok Asus

    Stevia gave both myself and my wife excruciating headaches immediately after consumption; we tried several forms: highly refined, natural, etc. They all caused the same horrible effect.

    • Al Bogdan

      It’s likely there is a subset of the population that is Stevia intolerant.

      Evidence seems to show that all sweeteners pose a risk of side effects. Honey, cane sugar, artificial and natural low calorie sweeteners. Humanity has never in the history of the earth had so much access to so many forms of sugar and sweeteners, so it wouldn’t be a surprise that our bodies are not able to handle unusual new chemicals or high sugar loads.

      While our cravings for sweetness served us in the past when sweet foods were seasonal, it seems to be an unhealthy addiction now. I always seem to feel much better when I keep sweets in general as a special event rather than a daily treat.

  9. Sir Lunch

    Hi Al…thanks for this post. I am an insulin dependent diabetic, and almost 15 years ago, I discovered a correlation between my peripheral neuropathy and artificial sweeteners. As such, I avoid them altogether, but I was at a friends place last night for dinner and cards with my gal. Her guy is diabetic but just on oral meds and diet, and they are both using the ‘keto diet’, you may have heard of it. In any case, she tries to come up with all kinds of options for both of them, but also for me, when I visit, and where dessert is concerned, last night she used erythritol, saying that it is perfectly fine for me. Within minutes of getting home, though, my PN went nuts, and both my feet felt on fire with electrical pain. Because I know that I am particularly sensitive to artificial sweeteners, I can only surmise that I am sensitive to these sugar alcohols as well. I know full on insulin diabetics that have no problems with Aspartame, which is that worst one for me, so that leads me to think it’s more my sensitivity than anything else, but still, my research brought me to this post, amoung (pardon the Canadian spelling) other websites as well…thx again

    • Al Bogdan

      Thanks for sharing your observation. Hopefully your comment will help someone else with a similar reaction.

      With all our scientific knowledge and abilities, it’s too bad we don’t have research assistance available (working alongside medical assistance) to help figure out what’s actually happening in situations like these. Seems there’s likely valuable information waiting to be discovered.

  10. ha f ley

    I’ve been searching bad side effects from erythritol for 6 mos now. Extreme lethargy is my main problem. I’m 61 and have been sugar free since I was 29. I switched to stevia 7 years ago. Recently I suspected erythritol and switched back to equal and felt normal again. Then I got paid and bought more stevia and the extreme lethargy returned. In all my research I learned that erythritol is made from fermented alcohol. Anything fermented feeds my latent yeast overgrowth. Thank you for writing this. There is a new stevia sweeter I found at walmart called Zing that does not have erythritol. I had no side effects from this one when I can find it.

  11. harley

    I’ve been searching bad side effects from erythritol for 6 mos now. Extreme lethargy is my main problem. I’m 61 and have been sugar free since I was 29. I switched to stevia 7 years ago. Recently I suspected erythritol and switched back to equal and felt normal again. Then I got paid and bought more stevia and the extreme lethargy returned. In all my research I learned that erythritol is made from fermented alcohol. Anything fermented feeds my latent yeast overgrowth. Thank you for writing this. There is a new stevia sweeter I found at walmart called Zing that does not have erythritol. I had no side effects from this one when I can find it.

    • Al Bogdan

      Yes, I’ve had no issues with Stevia, only the erythritol mixtures. We’ve been using “Stevia In The Raw” and have no issues with it either. Glad you figured it out.

  12. Sarah

    I’m amazed and delighted to find this article because I worked out a year ago that “stevia-sweetened chocolate” that actually contained erithritol was giving me brain fog but all the other reviewers of this product rated it highly. I was getting seriously worried and thought I might not be able to continue working but, within a short time of cutting it out, I was back to normal. I’ve had difficulty convincing anyone of this so this article is of great interest to me. I assume some of us are just much less tolerant of erithritol than others but there really ought to be some sort of warning on the packaging.SL

    • Al Bogdan

      I totally agree about the warning! It was awful what that sweetener did to me and how much I lost during that period of time.

      • Sheri

        Drs don’t always listen to their patients. If they haven’t learned it in med school, they may not believe the problem actually exists. Glad you never gave up. This article helps a lot of people.

  13. Mandy

    Thank you for your article, now I know I’m not going insane.

  14. Benedikt

    I’ve been sugar free since new year. Yesterday I bought a little bag of candy sweetened with sorbitol and maltitol. I had the worst flatulence I have ever experienced, and today I feel dizzy and total brain fog. Like you say, I almost feel intoxicated. Gum also makes me nauseaus. Looks like I’m gonna stear clear of all artificial sweeteners too.

  15. Laura

    I just tried Lily’s chocolate chips today. Within 20 minutes I started to feel sort of intoxicated. About an hour later I felt so tired and a little nauseated. I googled erythritol and tired and found this post after scrolling a lot. It is pathetic that all I can find are articles touting the benefits of it and very brief mentions of headache and stomachache if ingested in large quantities when it clearly does not have to be ingested in large quantity to cause major issues. I will not ever ingest erythritol again. Thank you for sharing the truth. It is helping people years later!

  16. C. Warner

    Thank you so much for this article. After eating chocolate sweetened with maltitol, I’ve had digestive problems. I hoped they would decrease as my system got used to it, as I was trying to eliminate sugar from my diet. However I then started to experience exhaustion and flu-like pains regularly. I recently wondered if there could be a connection, and after typing “maltitol causes fatigue” into Google, I found your article. Thank you so much!

  17. C. Warner

    Thank you so much for this article. After eating chocolate sweetened with maltitol, I’ve had digestive problems. I hoped they would decrease as my system got used to it, as I was trying to eliminate sugar from my diet. However I then started to experience exhaustion and flu-like pains regularly. I recently wondered if there could be a connection, and after typing “maltitol causes fatigue” into Google, I found your article. Thank you so much!

  18. Sheri

    I am so glad you wrote about this. There are so many people I have spoken to, with brain fog and often I’m one of them! I have an inherited challenge with the protein in milk, so lactose may not always be the problem. Anyway, thanks again. Stick with the real thing and watch the quantity.

  19. Lina

    Hello, I know this post is rather old, but I’ve had this doubt with erythritol for a while, now I know it’s not me being crazy. How long did it take for your symptoms to clear since stopping?

    I can’t tolerate any artificial sweeteners, stevia makes me feel awful!, aspartame migraines, etc… so in my quest to find something I started using erythritol and eventually figured it was causing my mental clarity and headaches (or making it worse at least)


    • Al Bogdan

      My extreme symptoms improved quickly. I stopped being dizzy and the numbness went away in a week or two if I recall correctly.

      I do still have to watch my diet. I’ve found that eating wheat-based baked goods makes it hard to keep my eyes open and I will crash out asleep in the middle of the day. Checked the blood sugar and that’s always good. Excessive fats gives me a headache. If I keep a healthy diet I feel pretty good.

  20. Nolwenn

    I have been taken erythriol (Pure Organic Stevia for 8 months. Conjointly with sucralose + caramel colour at every breakfast (FiberOne all bran). I was litteraly dying I swear God.
    Heart flattering, lowback pain link to kidney deficiency, stiff muscles, weak voice, brain fog, feeling out of space, difficulty focusing and all the above already mention in the posts. Impending doom and depression I have been considering suicide.People close to me encourage me to go see a psychotherapist but intuitively I knew the problem was physical and not mental. I choose to go consult an accupuncturist who told me many organs had been unbalanced. I started ten to think of food poisoning and chase for every ingredient I was putting into my mouth by reading labelling. This is how I discovered with horror but releaf that indeed I was right. I trashed every artificial sugar and these all bran packaging. Spectacular change after 24hours only: no more suicidal thoughts and my voice start is more clear, my joints more flexible, less backpain already.

    Thank you for this great article. Good luck to everybody. If only the authorities would bannish this poison and restaure healthy food in supermarkets !

    • Linda

      So glad to read this article. I also have been consuming Lily’s chocolate. I also have been having so delicious dairy free no sugar ice cream. I had an episode at work and was seeing stars! Felt light headed and like I would pass out! I even told the cashier about it while buying more chocolate! I am stopping right now. I buy these products in health food stores! What a shame!

  21. diana weirich

    I used stevia and my feet went numb. It took me 2 months to figure this out.

  22. Celeste Flasker

    I have been using erytritol in my coffee for 2 weeks and it was the only thing in my diet that had changed. I am dizzy all the time for 4 hrs after and tired. 3 days ago I didn’t use it for 2 days and was fine. Again I used it today and seeing stars and dizzy again. I will never use these artificial sweeteners ever again.

  23. Rhys Davies

    I’ve just had a very similar experience to this account above – with stevia – 2 different neurologists. Headaches, fatigue, dizziness, brain fig and eventually tingling in hands and feet.

    It was in my reduced sugar baked beans, ketchup, Huel Black meal replacement, soft drinks. Also in some of the coffee sweetners i was picking up in cafes.

    Stopped stevia and drastic improvements over a few days which have now sustained for months. Still some occasional tingling in feet which i have been told may take 12-18 months to reduce and hopefully resolve.

  24. Dan k

    Thanks for posting this
    erytritol was making me dizzy I almost blacked out, uncontrollable shivering, headache, tingling hands and feet, upset stomach after only a small amount. And only after eating erythritol. This page is the best resource on this issue. Keep up the good work.

  25. Matt Elliott

    I made some really tasty chocolate chip cookies with Swerve last night and started to feel off, like I was going to pass out. I Googled “erythritol and dizziness” and came across this article that leads me to believe that this was indeed the catalyst that led to my symptom. I’ve been using monk fruit and stevia with no issues. This was the first time using erythritol in baking and it will be my last.

    Thank you for putting this information out there for us that are searching for answers. I was on the verge of a doctor’s visit to see if I had a brain tumor! Thank God that’s not the case.

  26. Sharon Jenkins

    I’ve been begging the Drs to help me for a good 10 years, today they just ignore me. In the UK your assigned a dr according to the catchment area you live in so it’s not easy to change them unless you can afford private. Blood test after blood test said I was ok, I’ve been tested for everything. Prescribed codeine for the pain which I’ve been taking anywhere from 30, 60, 90 per day. If I didn’t take codeine I’d be in a&e having a seizures. In fact if I didn’t take codeine I wouldn’t have a life. I’ve been totally out of it, barley able to work, migraines, shooting pains all over my body, dead left arm, intense pain in all my organs to the point of having difficulty breathing, pain in muscles and bones, unable to walk far, no strength, very soar mouth. Dr said I might have fibromyalgia which I kind of accepted. Looking back now I noticed this illness more severe while doing keto. The only thing that got me researching today was I’d stopped eating my regular keto brownie about 2 weeks ago, guess what it’s loaded with erythritol. Anyway, My symptoms subsided a lot, but not totally. A couple of days ago I decided to make no flour black bean brownies (made with erythritol) because I was missing sweetness. I did no flour because I might have been allergic to coconut flour since I have a gluten and other nut issues. Bang, I came down so ill again. To me this is enlightening but now I’m worried ? if the erythritol has damaged my body because I didn’t totally recover when not taking it. I’d really like to sue the companies because I now have evidence, is that even possible? This has left me in shock at the thought of so many people being ill after eating it.

    • Al Bogdan

      Yes, the large number of comments I’ve received on this post show that many, many people are suffering from medical issues caused by chemically enhanced diets, specifically all those added artificial sweeteners. My guess is it depends on genetics and/or the composition of digestive bacteria in our systems. I removed all sugar alcohols from my diet and it helped considerably. I found it useful to reduce high fructose foods temporarily while my system recovered, as while not as bad as sugar alcohols, fructose is more difficult to digest than glucose. I also now try to only consume dairy with A2 casein, as A1 casein is also very difficult for many people to digest (I use enzyme capsules when eating A1 dairy) and can trigger similar reactions as sugar alcohols. The dairy industry switched to mostly A1 producing cows because they produce more milk, but that milk is harder to digest. I also try to limit emulsifiers in processed foods, like ice cream, as I found it disrupted my digestive biome when consumed daily. It appears there’s a tolerance level we all have as to how many undigestible things our digestive systems can handle, and modern food processing, manufacturing, and marketing have substantially increased the foods we consume that our bodies can’t tolerate.

      I hope you recover and find your way back to a reasonably normal life again!

  27. Vlad

    Oh my God, I’m not alone! Recently, by taking everyday notes about my meals, I’ve discovered by myself the reason of my brain fog, poor concentration, dizziness and memory problems! It’s erythritol that I’ve been using for this whole year, because I feel ok when not eating it. I started googling and found this page to confirm even more my observations. Guys, we need to spread the information, because physicians suck! They wanted to prescribe me antidepressants.

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