Onion Intolerance

Intolerance to food is a mild reaction to some or all of the compounds in it. This is often confused with allergy as the symptoms may be similar. The major difference between the two is that allergies attack the immune system and affect many organs. Intolerance on the other hand, is limited to the digestive tract. Onion intolerance is described as mild reactions to food containing onions often characterized by the inability to digest them . This condition often goes unnoticed by some victims who don’t experience all of the symptoms of intolerance to onions. Many just suffer bad breath after consuming onions. It goes away soon after brushing so they don’t pay much attention to it. According to extensive studies, a type of protein present in onions, reacts with various antibodies to trigger excessive production of histamine which goes on to inhibit bodily functions like digestion. The lack of vital enzymes for digestion of onion proteins also leads to the following signs of onion intolerance.

French onion soup is definitely off-limits if you're onion intolerant.
French onion soup is definitely off-limits if you’re onion intolerant.

Signs of Intolerance

The sufferer is likely to exhibit signs of restlessness when onions are being cooked and this may be followed by nausea. This is as a result of sulphur in the onion that might smell foul to some. Hives and sores on the mouth are a common sign of onion intolerance. These symptoms last about a month and patients are very uncomfortable. He/she has to deal with itching all over the body which later leads to irritability. People with intolerance of onions are prone to migraines and may lose focus at times. This is due to histamine that inhibits normal bodily functions. Bloating is also a common occurrence among those who suffer this condition and it is mostly coupled with stomach cramping. Victims may also experience swelling on the face as well as skin reactions. If these symptoms go unattended, intolerance escalates to allergy with the victim suffering shortness of breath, confusion or in some cases death.

Treatment for Onion Intolerance

The easiest way to curb onion intolerance is to stay away from them for sometime. It helps with the symptoms and once they have disappeared, you may choose to eat them again to see if the intolerance is gone. Experts at food intolerance guide their patients with intolerance to raw onions to start cooking them. However most people are allergic to cooked and raw onions alike prompting physicians to employ more decisive tactics. As stated before, onions trigger the production of histamine so a treatment program will involve the intake of antihistamines to reduce swelling. For the skin, hydrocorstine is administered. In cases of extreme intolerance (allergy), injections of epinephrine are recommended. If you witness intolerance onions, it is best if you see a doctor so they can determine whether you bear symptoms of intolerance or otherwise. This is because when intolerance is left without treatment, the patient may suffer severe allergic attacks in the future. It is very likely that people with this condition cannot tolerate onion related foods like kale, garlic, and chives. It is safe to steer clear of processed or canned foods as they contain onions in various forms.

27 thoughts on “Onion Intolerance”

  1. Hey, your blog is really nice! I just have one question: when I eat onions (raw mostly, I have no problems with onion rings, for example), I don’t experience any skin reaction, but after a few hours I get sympthoms like mild fever, strong headache and sore throat. Have you ever heard of this? Am I allergic?

    1. Note that I am not a doctor, so take this with a grain of salt, OK?

      From what you are describing I wouldn’t rule out onion allergy, but it sounds more like an onion intolerance to me.

  2. thank you so much your information was really helpful. when i eat onions i experience hives , nausea and rash on my face. i used to think that i was reacting to changes in weather. however since i stopped taking onions i no longer experience rash and hives. i don’t know whether this is just food intolerance or an allergy

    1. I read up on Onion allergies and it matches what you stated here, I think it’s on another page on this website, have a look.

  3. Hi there! :)

    After I eat onion (raw, cooked,red or white – also garlic) I will wake up and feel very off. I can taste it in my mouth still, even after brushing and mouthwash. I also get quite gassy & bloated. I had a bad gut ache thismorning and nausea on the way to work after eating a small amount of red onion lastnight. I am also prone to migraines, but I haven’t noted lately if that’s due to me eating onions or not. In your opinion (I note you’re not a GP :)) Onion intolerance or allergy?

  4. Kale is a leafy green vegetable belonging to the Brassica family, ie cabbage, brussel sprouts and brocolli. I think a more like relative would be leeks.
    Not to say that one doesn’t get similar quantities of gas discomfort from the Brassica family.

  5. Hi – useful page – I love eating onions, but now I am sure they do me no good. Itching all over and a smell like diesel fuel? A smell i associate with onions. I ate some yesterday to see if the reactions would show up – bang, yes they did! have a welt or hive behind my right leg. itching where the sun doesn’t shine. Increase in wind too. Seems I’ll have to watch out when eating Garlic/Onions. Meant to be really good too for the blood? Seems like I’ve been Intolerant for years. Yet another thing I cannot eat on the healthy veg diet.

  6. I am terribly intolerant. It seems to be getting worse. I just ate a bag of chips without checking the ingredients and I am paying for it now. Onion powder. :/ It causes pain in my stomach equal to that of labor. (I’ve had two kids.) The only way to stop the pain I experience is to take a pain killer. It’s that bad, and it’s really interfering with my life at this point. I have also figured out they were the cause of my panic attacks. I would get to where I could not breath and freak out. I should probably go see a doctor, but I don’t want to have even more medical bills racked up for them to tell me to avoid onions. When I’m in the middle of one of these attacks it’s not possible to go anywhere. I was doing good for a while avoiding the onions, but I swear they sneak those little bastards into everything!

    1. That is EXACTLY what I keep telling people – it’s exactly like labor pain! I also have had two kids. It is MISERABLE! I’m on this never-ending quest to find answers. So far, I have come to believe that it has something to do with the pancreas and a lack of enzymes necessary to digest onions and other sulfur foods (and even some foods and beverages that contain sulfites). Someone suggested I take an antihistamine, and I have found that this does work in the milder cases I have had when I consume only a small amount of onion. For major cases, I still have to take a Percocet, but I am running low as doctors will not prescribe Rx pain meds for abdominal pain of this sort. In the UK, there are reports of people having great success with sodium chromoglycate. I am going to look into this further to see if it is an option in the US. Best of luck to you! Good to know we are not alone in our suffering! Also check out onion intolerance group on Facebook. Lots of support and information there!

  7. Hi there, great site.
    I have a quick question regarding this statement in the original article: ” The lack of vital enzymes for digestion of onion proteins also leads to the following signs of onion intolerance.”

    I was hoping you could provide some references for which enzymes and which onion proteins you are referring to?

    I’ve had onion intolerance for as long as I can remember, as have my father, uncles, and grandfather – so very likely genetic. This is an intolerance to eating uncooked onions, digestive symptoms only – no headaches or skin issues. I’ve never encountered a molecular explanation for it before, and am super curious.

    Can you please let me know which enzymes and proteins you are referring to?


  8. My girlfriend has an intolerance to Onion, Garlic, and in general Allium genus. Minor quantities often suffice to block her from eating anything for a day or more.
    She also dislikes cabbage and related foods, also wine.
    The common thing among them is some sulphur compounds, although she displays no discomfort when consuming eggs, bacon or other sulphur-rich foods.

    I think that when a person is intolerant to garlic, then he/she might have no intolerance to other Allium species, but when the person is intolerant to onion, then he/she usually is intolerant to all other Allium plants.
    I wonder why there is no obligation to inform the consumer about the presence of onion or even garlic. Among all the people I know, only one is intolerant to something other than onion, and he is 7 months old lol. An old teacher of me was allergic to alcohol (breathing it, not drinking it, since he used to drink Ouzo daily). Apart from my girlfriend I know several people that are intolerant to onion.

    And, yes, it’s fucking everywhere. Sneaky.

  9. I have found myself to have a migraine reaction to eating raw onions, any color. It has gotten so severe I have become nauseous and vomited, missing a day of work… not only from vomiting, but from the migraine, they usually last 2-3 days. I also experience blurred vision and sensitivity to bright lights. My reaction has grown to not even being able to peel, slice or dice any raw onion, let alone be in the same room when one is being prepared. The raw onion smell alone is a trigger for a migraine for me. The smell on my hands from handling them is an issue as well, as they tingle and sometimes get numb. How do I clean the onion juices off them? I’ve tried a variety of lemon type soaps and even gone as far as bleach. They do not seem to bother me once WELL cooked. This has accelerated in the last few years, I am 48. I currently take an antihistamine for seasonal allergies on a daily basis. This does not seem to help whatsoever. Can I take anything more when I run into this problem? Ibuprofen and Acetaminophen do not touch my migraine, nor any migraine type medicines. Recently, I had a chicken salad sandwich in a restaurant, not knowing there was raw onion in it and I had a headache within the hour which lasted 2 days. Any suggestions? I love to cook and eliminating onions completely seems drastic.

    1. Hi Lori
      I don’t think there is any solution other than to avoid raw onion. I can’t eat it, but can eat it cooked, and I find it really annoying that it’s added to dishes in restaurants without being listed on the menu. I always ask now, and then request it without. For cooking, I use bags of ready chopped onions – I tip them into the pan without even touching them. I can’t bear to fry them, if possible I boil them in something like tinned tomatoes or white wine. Or I ask my husband to do it!

  10. I get migraine from onion and my intestine seizes up for a couple of days. Before it comes on I feel tired and irritable. It began when I was about 35 when I started to get mega low end wind when I had onion soup and got worse!!!! I have had reduction in it happening from taking pycnogenol which is GRAPE seed [NOT grapefruit seed] extract or Pine Bark extract and also from doing urine therapy which enabled me to stop buying Pycnogenol. I find if I can persuade the intestine to let go the headache eases. I can do that with EFT and Reiki but takes a while. I took a colloidal mineral supplement a while ago which seemed to be healing all of my allergies and intolerances but they took it off the market saying it had too much aluminium. Who knows?

  11. I have a friend who has very violent reactions to onions and garlic. We have found that the prepared pre-minced garlic seems to do okay but fresh or dehydrated garlic cause reactions. She attempted to go through allergy treatment in hopes to lessen the effects, but as with most people allergic to food allergies (peanuts, for example) , the treatment was unsuccessful. Even eating food that has come in contact with onions (i.e. salad garnished with fresh onion rings) causes a reaction. She had tried both yellow and white onions and we are wondering if other types (such as red, leek, or spring) all produce the same enzymes that trigger her reaction. Any ideas? We were just chatting about it tonight. I ran across this blog and thought I’d ask if you knew. Thank you for any feedback you might have. Blessings.

  12. Question, If I eat anything with onion in it. I cannot swallow . My throat closes up Could this be an allergy to onion. I can peel onion & cook onions, I just cannot eat anything with onion or onion flavored items.
    Thank you.

  13. Onion sensitivities are very serious – so I don’t understand why restaurants use these so abundantly and without warning?

    I can’t put an onion in my mouth without a gag reflex of instant vomiting. I can sometimes eat cooked onions but this leads to fever, diarrhea within an hour, and later vomiting (not instantaneous). I also suffer from extreme migraines, so even though I stay away from onions at all costs, sometimes it’s unavoidable and I find the migraine link quite interesting.

    I am happy to see this forum because I don’t think a lot of weight is given to onion intolerences, etc. They can be very serious and quite real. I find it very difficult to order “safe” food in restaurants, and hope this helps people realize it’s okay to take that extra time and make sure you order something that won’t make you sick, nevermind might enjoy :O

  14. For the past 5 years after I eat raw onions my body wants to sleep within an hour or two. I’ve tried my hardest to stay awake and I can’t do it. I call it the “onion coma”. Also, it’s not a good sleep. I get a lot of people telling me to just eat an onion if I can’t sleep. It doesn’t work that way. I feel horrible after waking up (all the energy has been drained) and I usually only get around an hour of sleep. Lately, the effects don’t kick in until the next day. Really strange.

  15. It is to my understanding that this post was made a couple years ago. I noticed when I eat onioms, later in the day my heart rate increases, I have bad abdominal pain and nausea. I want to know what I could do. I’m so sick of this.

  16. Took me to 30 y. to work out the strange migraines and stomach issues i got were caused by onion or garlic – worst when stewed or baked. Stomach too. Gaviscon, paracetamol and your head in the hottest bath helps ease it. Avoidance the only cure. Try a week without and you will be amazed – I think my reaction is worse if adrenalin in my system and alcohol makes that bad. Try telling some restaurants that real Italians don’t use onions in lasagne….

  17. Hi there, i’m glad you posted this! its nice to know I’m not alone!
    I have a severe intolerance to onion, chives and shallots. Unfortunately i was fooled by a jar last night and have been throwing up constantly ever since. I get nauseous, cramps, diarrhea, vomiting.. the works!!
    Apparently I have had it since a kid, we just didn’t know. I was THAT kid who hated spaghetti (because my mother woulds put onion with mince)
    Taking it out of my diet all together, my condition got worse, first it was only feeling sick now it has become more serious. The only thing I have found helps is taking an antacid(Gaviscon), pain meds and going to bed with a hot water bottle.
    My suggestion? Google homemade pasta sauce recipes

  18. I suffer badly with onion intolerance, it used to be it just repeated on me (burps, bit of bloating, bit windier than normal) and have found for me it’s the sneaky onion that stops me in my tracks……
    Onion powder
    Onion salt
    Onion extract
    And the other ways they sneak onion into supermarket bought foods…….
    Fresh onion gives me stomach issues….. With in 10 mins of ingestion
    Sneaky onion takes longer 8-12hrs and doesn’t affect anything but my intestines……. Cramps, excruciating pains ( hospitalised twice for appendicitis…)
    Then comes the ‘purge’…….. Once started ain’t being more than 10 feet from the toilet…….( no need for details there..!)
    Once ‘purged’ it’s as if nothing was wrong…..??
    I HATE onion……… As a child I had it in everything, into my 20’s too…….
    Early 30’s I kicked in and has progressively gotten worse….. But I think I know the signs better from sneaky onion now and manage the ‘fallout’ better these days….. Hoping my 40’s are onion

      1. Same thing for me. It’s worst in restaurants and eating out. I used to get just a gurgling tummy but recently find it affects my breathing At home I just make substitutions such as celery and fennel for texture and flavour. For curries I mince the onion then fry it to obliteration. I am really interested in this enzyme thing but can’t find enough info. It also runs in my family. I find it’s worse as I get older. Strangely I love garlic and chives, even uncooked, but if I come across garlic cooked without frying first I really find it repellant. Leeks are less revolting than onion, but I still don’t want to eat them. People don’t understand this intolerance They ask for reasons. I wish they would just accept it, it’s as if they think I am to blame

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  20. Hey there I am so glad to read this, I turned 30 this year and have apparently developed an allergy to onions. If I smell them raw or eat them about an hour later I am sick at my stomach and I will vomit all night and the next day. It’s as bad as a stomach virus and if I do not vomit then I continue to be sick for days. When I do vomit the onions have not digested at all. I know gross and graphic but I am so glad to am not the only person with this problem. It takes me 2-3 days to get over this. My blood pressure changes, I am nauseated, I have fever and headache and I wake up having to vomit all hours and I found that the only way for me to feel better is vomiting then sleeping for literally hours. Anyone else have these same reactions!? I do not have hives or anything else

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