Q. My partner just ate one Brazil nut, and within minutes his tongue swelled to five times its thickness and double its width. He could barely talk.

He took an antihistamine (chlorpheniramine) and we called the doctor. The doctor said that if the reaction worsened he should go to the hospital. He has no allergies to anything else and never knew he was allergic to Brazil nuts. Neither of us had any idea they were so dangerous.

A. Your partner will need to avoid Brazil nuts in the future. Allergic reactions to these nuts are not uncommon, and they can be life threatening. Some people experience a reaction that requires emergency medical treatment with epinephrine.

The traditional holiday nut bowl may lead to unexpected exposures. Here is a report from another reader: “For years at Christmas my eyes would get irritated and watery. One holiday season I was at my friend’s house and his children needed some nuts cracked. I picked up a Brazil nut and cracked it.

“Within seconds my eyes started watering, so I rubbed them with my fingers. Within one minute my whole face had swollen up. I looked like Rocky (at the end of Rocky part 1). There is always an open bowl of nuts somewhere at Christmas time, but now I avoid them.”

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  1. Kevin
    Denver, CO USA

    I ate Brazil nuts for years, even though I did not like them because they made my lips tingle. Then one Christmas Eve, I was visiting my parents and I ate out of a bowl of mixed nuts. Within 15 minutes I had gotten dizzy and nauseous, so I went to the bathroom because I thought I might be sick.

    That’s when I got so dizzy that I fell and hit my head on the counter, and then I broke out in hives, and I couldn’t breathe. I was hyperventilating but I could not get enough oxygen because all of my capillaries had dilated. It has also happened with pumpkin seeds, split pea soup and Macadamia nuts. When I got a full allergy testing, every single one of those things turned out negative.

  2. Norah

    Half an hour after eating chocolate covered brazil nut I felt dizzy, my blood pressure started to fall and I started vomiting. At the start I thought the chocolate was contaminated so I went to the store which I bought it from and told them what had happened, they asked me if am allergic to nuts. Since I usually eat other nuts without problems, I confirmed to them that was not allergic. And later I bought a brazil nut chocolate from other brand, when I ate it I had the same symptom dizziness, vomiting, light head.

    So I think I have allergic reaction.

  3. Chris

    I have known of my severe and potentially fatal allergic reaction to brazil nuts since I first ate them as a child. Severe swelling in my lips and eyes, and worst of all my throat which inhibits breathing, then if I get through that its stomach distress and finally an explosive itchy rash spreading from soft spots like armpits, the neck and behind the knees. Its like I’ve eaten some kind of allergy grenade.
    I am also allergic to cashews and less so to pistachios and hazelnuts, but not to almonds, macadamias, peanuts or walnuts. I also have a very extreme reaction to poison ivy which though not potentially fatal has caused the most distress over the years.

    A while back some research into these allergies turned up a chemical called urushiol which seems to be present in the things which I am allergic to, including most significantly the two heavy-hitters of poison ivy and brazil nuts. The compound was also significantly present in the skins of mangoes, which I seem to remember having a slight reaction to though I eat the fruit with no problem, and a wild plant in Japan known as “urushi” from whence the name derives.

    I personally just try to stay away from the stuff. I am posting this just to let anyone out there with a similar condition know what I’ve come across and I hope that it can help others in their own investigations.

  4. Dara

    I’ve known I am allergic to Brazil nuts since I was little. Fortunately for me, it causes no more than hives and itching on my tongue and lips. It’s sad: I had some a couple of years ago, and they’re very tasty. It’s my only food allergy. I really wish I knew what substance in them I’m allergic to.

  5. Gina

    Hi I ate just Brazil’s and my mouth throat and swelled now I’ve eaten this type of nut for years with no problem then a few day later I was eating a cookie and I didn’t realise that. It had Brazil nuts in them and it happened again but because I ate 1 and a half cookies and the allergy was worse and I had to take 2 antihistamine before I was ok again to be honest it’s scarring me wot should I do

  6. KLM

    I ate 2 brazil nuts and my mouth was stinging and burning and my gum on the inside had a knot in it after, about an hour the knot was gone. I guess I’m allergic to Brazil nuts however I eat other nuts and do just fine.
    I’m also allergic to shrimp.

  7. scuba22

    I ate chocolate covered CRANBERRIES, Ocean Spray to be exact. FOUR of them. that’s it. within seconds an area of my lip that apparently had contact started to swell… it grew before our eyes and my breathing became labored, but both the swelling and tightness maxed out after about 20 minutes. I had a weird tingling feeling that lasted took 3-4 hrs and it took that long for the symptoms to begin to resolve.
    The next day my partner looked at the bag of chocolate covered cranberries and in tiny print on the back: “processes in a factory that processes tree nuts”.
    !! OMG !!
    I know I am deathly allergic (read: hospital/ephinephrine) to Brazil Nuts and would have never thought that this was a potential food of cross contamination.
    I’d like others to beware!

  8. BA

    I have an allergic reaction only to BRAZILIAN nuts. It may be the element found in them (Selenium).
    Dietary selenium comes from nuts, cereals, meat, fish, and eggs. Brazil nuts are the richest ordinary dietary source (though this is soil-dependent, since the Brazil nut does not require high levels of the element for its own needs). In descending order of concentration, high levels are also found in kidney, tuna, crab, and lobster.[16][17]
    I found this while doing research on elements/compounds reported on from “The Water We Drink” (local municipality report). I decided to look into selenium and what it does for us as humans.
    That is what I found.
    I’m not sure if it is the element responsible for my allergic reactions to the nut. However, no other nut makes me feel allergic at all. I eat this one and bam! the allergies are horrendous.

  9. BHL

    Thanks for this vital info! I had heard that one should eat no more than ONE Brazil nut a week (because of the excessive selenium, I believe–even tho selenium is considered a necessary dietary element). I had not heard of these acute reactions, so I am forewarned. Many mixed nuts sold everywhere contain Brazil Nuts. Buyer beware!

  10. mpc

    I, too, can go into anaphalasis from Brazil nuts but also Hazelnuts, which are in many things now such as salad dressings, muffins, etc. Hard to avoid. So I am very careful. Have had this reaction since a child. I have ended up in ER with epinephrine being IV’d into me. Watch out!!! And ask, ask, ask if you can what is in something, before you take a bite.

  11. Greg Pharmacy Student

    JWH and A.C. Hegeman,
    JWH — I’ve heard on a number of occasions of new onset allergies, friends who had never been allergic to something and now they have allergic reactions. I’m not positive, but it seems like this would be logical. As the body ages and changes so do their allergies.
    A.C. Hegeman — I believe current it is still recommended to have an Epi-Pen if a severe allergy exists. Of course this must be prescribed, it can not be bought without a prescription, and it is NOT without risk to use an Epi-Pen. The risks and benefits should be weighed with a health care professional.

  12. Nancy H.

    I have dealt with allergic asthma for years and pretty well know what to avoid— dusty, old storage rooms, cats, scallops, etc.
    To my surprise, I had a SEVERE reaction—urticaria or hives all over my torso, watery eyes and compromised breathing. I went to a n ER for an asthma treatment. The only food I ate which was different was chocolate covered almonds from a nation wide grocery store chain. I contacted the home office and they said any part of the nuts and/or the chocolate covering and all the other ingredients could have provoked the allergic reaction. Now I simply avoid that product.

  13. C.S.

    You always write about the benefits of tart cherry juice for arthritis sufferer. My question is, how much has a 200 pound person to drink to benefit from it as the juice is very expensive. Thanks for your answer and all of your advice,

  14. ljb

    I had similar reactions to mixed nuts several years ago, including canker sores. I suspect it was something the packer added to preserve the nuts, and knew I couldn’t be the only sensitive one. When I complained to the packing company, I was told nobody else had complained, but they’d look into it. Now I have no problems with the same mix of nuts from the same packer.

  15. A.C. Hegeman

    Need to carry an epipen at all times probably should to be added. Or is this no longer advised?

  16. jwh

    I have eaten all types of nuts all my life (I’m 70) and never had a single problem. At Christmas ’09 I ate a handful of almonds and an hour later had the same symptom – a badly swollen tongue. My throat / airway stayed open, I didn’t panic, and the swelling started to go down in about 30 minutes. Needless to say, almonds are on my “Don’t Eat” list. I still eat other kinds of nuts without a problem.

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