Why Does Sugar Give Me a Headache?

Why Does Sugar Give Me a Headache?

Does eating sugar give you a headache? You are not alone.

The sugar headache, otherwise known as the Holiday Headache (because we eat so much sugar on Easter, Halloween, Christmas and other holidays) has a lot in common with a hangover but it can strike at any time we overdose on sugar.


While most of us have experienced a sugar headache at some time in their lives it is not well-known in medical circles. It might even surprise you to learn that the exact causes of all headaches are a bit of a mystery. Scientists have discovered that both migraines and cluster headaches change blood flow in the brain,  but exactly how blood flow changes create a headache is unknown. The same is true of the sugar headache.

I view the sugar headache as a toxicity or dehydration event and while it might be an annoyance, it could also be the sign of something more dangerous. Let’s look at dehydration and toxicity and see how they might cause a headache.

Sugar Dehydration

Dehydration is a common way to get a headache and sugar can lead to dehydration. Eating too much sugar pulls water out of your body in two ways.

  • Dilution: When you eat too much sugar, your body has to dilute that sugar to keep it from harming your body. This means that water is pulled from all parts of your body to balance the large amount of sugar in your blood stream. While this water-pulling effect happens all over the body, it is your head that suffers the most.
  • Urination: One of the ways that your body has of getting rid of excess sugar is to dump it in your urine. This is especially true of diabetics, who have to go to the bathroom a lot.


The other way to think about sugar is to consider it a toxic event.

While your body runs on glucose (a simple sugar) it was never meant to have a ton of simple sugars running around in your blood. If you look to nature, you would find that there are almost no foods that contain the high amount of sugar you would find in any soda or piece of cake. If natural foods do contain a high amount of sugar it is often bound up and hard to get to (like in a sugar cane). The only way to get a large amount of sugar into your body is to have that sugar processed before you put it in your mouth.

Processed sugar and processed grains both act like sugar in your body and this is toxic to the very blood cells that carry the sugar throughout the body. (I explain this at length in my book Sugarettes).

Something Worse?

Sugar headaches can also be a warning. If you get sugar headaches often, you might just be diabetic or pre-diabetic. The best way to find out if you are diabetic is to go and see your doctor and have them run some blood tests, but here are the typical symptoms of diabetes:

  • Excessive urination: As I mentioned above, sugar acts like a diuretic and will spill sugar and water into the urine. Having to urinate a lot is often one of the first signs of diabetes.
  • Excessive thirst: Since diabetics are losing a lot of water (see above), they are often thirsty all the time.
  • Excessive hunger: Everyone has periods of time when they are hungry, but diabetics are hungry all the time (with strong cravings for carbohydrates, sweets and sugar). This is one of the strange things about diabetics: They have a lot of sugar in their bodies, but it is not being used by the cells so they are hungry all the time.

Sugar Headache

The reasons why sugar gives you a headache are many and not readily understood, but you don’t have to wait for a reason to stop the pain in your head.

You can stop your sugar headaches and give sugar the boot by trying my 30 Sugar Free Days Program. During the program, you will learn about foods that act like sugar and what you can do about your cravings. Make sure you understand that sugar is doing more harm to your body than just giving you a sugar headache, take this opportunity to learn from your headache that you shouldn’t be putting large amounts of sugar in your mouth and you need to make a change.

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About the Author

I'm Dr. Scott Olson ND. I'm a Naturopathic doctor who specializes in diet, health, nutrition, and alternative medicine. I've written numerous books and articles on health, medicine, and alternative medicine I want to help you get healthy! Take a look at my blog and make sure you join in the conversation!

190 Comments on this article. Feel free to join this conversation.

  1. Matt Nicholas September 27, 2015 at 10:38 am - Reply

    Just wanted to add my vote to the ‘headaches after eating sugar’ – I get this every time now without exception. Every time I have processed sugar or even a lot of natural fruits at one go, a huge headache is certain to follow and lasts at least 24 hours. I’m 42, male and about 17 stone. I’ve lost 1.5 stone this year mostly by cutting back on the sugar. I never had this problem until a year ago.

  2. Kristen September 22, 2015 at 5:51 pm - Reply

    I have been getting horrible headaches the last two weeks and I have noticed it seems to happen whenever I eat sweets. I eat very clean, mostly gluten free/all natural foods. This last week I’v splurged and have been eating cake, cookies, etc. and after I get these horrible headaches that feel just like a hangover and it lasts all day. It doesn’t happen when I eat “good sugar” such as fruit. Could it be because my body is so used to nutritious food that these bad sugary foods are causing my headaches?

    • Dr. Scott September 25, 2015 at 5:36 am - Reply

      Hi Kristen, yes that could be what is going on. More likely, when you eat those foods you are causing inflammation in your body and your brain is especially sensitive to inflammation. Sounds like you are on a good path (most of the time). I would suggest simply listening to what your body tells you is good to eat.

      Dr. Scott

  3. Kristian August 24, 2015 at 5:07 pm - Reply

    I suffer from headaches/migraines quite often. I have worried about diabetes because it runs in my family and I had gestational diabetes in both of my pregnancies.

    I am trying to eat better by eliminating sugar and eating fruit instead. I just blended frozen berries with no sugar added grape juice and immediately got a headache.

    So far when my sugar is checked it is good.

    Can sugar from fruit cause headache or is there something in the NO ADDED SUgar Grape Juice?

    • Dr. Scott August 25, 2015 at 6:14 am - Reply

      Hi Kristian,

      Yes, fruit sugar can give you a headache, but also the No Added Sugar Grape Juice probably has an artificial sweetener that can also cause headaches.

      Dr. Scott

  4. Pearl August 24, 2015 at 12:22 pm - Reply

    I’ve had a headache since saturday and no otc pain pills is helping. I’ve noticed it happens when I’ve had too much sugar or if I eat salt and vinegar crisps.
    I’ve tested my glucose levels and it’s 4.1 mmol/l. They headache will stay constant on right side for a period of about 3 days.
    I am a typical migraine sufferer as well but these are worse because of the duration and the constant pain behind eye and occasional sharp pain.

    • Dr. Scott August 25, 2015 at 6:18 am - Reply


      Sugar can definitely trigger headaches, but so can grains and foods that act like sugar. You should consider going on a sugar free diet (that excludes grains) and see if that will help your headaches.

      Dr. Scott

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