Ever hear of a Lettuce Allergy? What about the 5 Alternative Causes?

If you think you're allergic to lettuce, this article will help
Think you have a lettuce allergy? You might be allergic to lettuce… or it might be something else. Don’t worry. I have you covered in either case in this article.

 

Lettuce allergy should be censored… or at a minimum, I feel this post needs an MPAA rating of 13+  But not because I’m planning on using profanity or showing pictures of dancing in a barn outside of the town limit (I don’t even know what it takes to get a PG13 rating these days!)  This post should be censored because I don’t want my kids… or any kids… ever to use lettuce allergy as a reason they don’t eat their dinner.

 

But, yes, there is such a thing being allergic to lettuce.

 

But what is interesting is when someone has a lettuce allergy; they’re NOT really allergic to lettuce.  Which is why I made this post to discuss a true lettuce allergy and also 5 common causes of a false lettuce allergy (where you think you’re allergic to lettuce… but aren’t!)

Overview

 

Lettuce Allergy Symptoms

A true lettuce allergy follows the same symptom pattern as any IgE-mediated food allergy.  If you are allergic to lettuce, eating the leafy greens should cause these symptoms:

  • Hives (present in 90% of people with food allergies)
  • Swelling of the face, hands, feet
  • Abdominal pain, diarrhea, constipation, cramping
  • Shortness of breath, wheezing, or difficulty breathing
  • Lightheadedness or dizziness
  • Confusion or feeling of passing out
  • “Feeling of impending doom”
  • Death (although I’d prefer if you caught it before this step)

In addition, these symptoms should happen every time you eat the same lettuce.  I’ve even dedicated the first part of this article to help you with your true allergy to lettuce!

 

But that’s not usually what happens!

 

Instead, lettuce allergies seem to show up sometimes and no other times.   Because of this, you might think you’re allergic to a specific lettuce or to a ‘pesticide’ used on the lettuce.  Or perhaps it’s confusing and inconsistent enough you think a particular zodiac sign mixed with a waning crescent moon and something-something Jupiter is causing your allergy.

If this second part sounds like you (or you want to read about the awesomely entertaining world of leaf vegetables), then take a couple minutes to read this article or just jump down to read the 5 common causes of a false lettuce allergy (Spoiler alert:  they are not due to lettuce!)

If you’re unsure if your lettuce allergy is a real allergy vs an intolerance:  I have a post dedicated to food allergy vs food intolerance that can help you determine the cause of your symptoms.

 

Picture of different types of lettuce showing steps to take if you have a lettuce allergy
Here are the steps to take if you are truly allergic to lettuce

True Lettuce Allergy / Anaphylaxis Treatment Plan

If you (or a loved one… and not your picky eater child) have a true lettuce allergy, you’re not alone.  But don’t worry… I have a plan for you!

These are the 3 steps you need to take if you’re allergic to lettuce:

 

True Lettuce Allergy Step 1:  Avoid Lettuce

There are 5 main types of lettuce: Crisphead or iceberg, summer crisp, Butterhead or Bibb, Romain and Looseleaf.  These types may differ with taste, how to grow them, how they’re used, etc, but they’re all a part of the daisy family (Asteraceae).

In theory, if you have a true allergy to lettuce it is likely you will react to all lettuce varieties.  I can’t find studies showing this level of detail, though, so this is my best guess.

So it would be best if you avoided all lettuce types.

 

True Lettuce Allergy Step 2:  Epinephrine

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All IgE-mediated food allergies should have similar plans:  avoid the food and have an epinephrine autoinjector available in case of accidentally ingestion.

Getting epinephrine is an important part of a lettuce allergy since it has a high (60%) chance of causing a life-threatening reaction.[1]

Now, I understand that it is difficult to “accidentally eat lettuce.”  In my entire life, I’ve yet to eat a food and think “oh man, wait a sec… someone snuck lettuce into my meal.”  So avoidance is easier than some of the other food allergies.

But you should have an epinephrine, such as Auvi-Q, prescribed just in case (bonus:  for 2017, Auvi-Q is $0 out-of-pocket cost for most people).

 

True Lettuce Allergy Step 3:  Other foods

An allergy to lettuce is due to an allergy to something called a lipid transfer protein (LTP).  This is significant because a good deal of lettuce families and other vegetables share this LTP protein.

One of the better studies looked at 30 patients allergic to lettuce.  They found 18 of the 30 (60%) had SEVERE, LIFE THREATENING allergic reactions to lettuce.[1]

What they also found is that if you have a lettuce allergy, you were also more likely to have allergies to other foods high in the same LTP.  Of the 30 patients in the lettuce allergy study, 43% were also allergic to other foods including:

Food Chance associated with lettuce allergy
Peach90%
Tree nuts90%
Legumes33%
Tomato30%
Cereals20%
Mustard20%
Melon17%
   Runner beans13% (damn fitness veggies!)

 

This does NOT mean you need to stop eating these foods.

 

What it means is that if you have any reaction to these foods, even if you consider them mild, I would recommend seeing an allergy specialist to find out if you are allergic to them or not.

 

Sometimes you're not allergic to lettuce but to other foods.
Sometimes your lettuce allergy is NOT due to lettuce! Here are 5 alternative causes for a lettuce allergy.

5 common causes of a false lettuce allergy

Although there are people who have a true lettuce allergy, the majority of people who think they have a lettuce allergy don’t!  The rest of this article is to help you figure out other possible causes of your “lettuce allergy” symptoms.

 

Oral Allergy Syndrome (aka food-pollen syndrome) is where your body confuses pollen allergy with food allergy.

1.  Lettuce Allergy – Alternative Cause #1:  Oral allergy syndrome

Oral allergy syndrome (OAS, also known as pollen-food syndrome) is probably the most common cause of thinking you’re allergic to lettuce when you’re not.  In fact, in oral allergy syndrome you’re not allergic to food at all!

Pollen-food syndrome is a condition where you are allergic to pollen and your immune system recognizes certain food proteins as pollen, causing mouth or tongue itching, scratching, or tingling that almost feels like ‘seasonal allergies in your mouth.’

Oral allergy syndrome is seen in people who have an allergy to ragweed and then react to bananas or melons (watermelon, cantaloupe, honeydew).  But there are many cross reactions recognized.  I am writing an article covering oral allergy syndrome but you can read a great paper about it here (man, that author really seems to know his stuff!)

If you don’t have a true IgE-mediated lettuce allergy / anaphylaxis, it is possible that your lettuce allergy is due to oral allergy syndrome.

Contact allergy to lettuce is common
Contact allergy to lettuce is a common problem. Not in my garden, though, as my lettuce looks like sick, wilted leaves.

2.  Lettuce Allergy – Alternative Cause #2:  Contact allergy

Lettuce can also cause a contact, or skin-only, allergy.  A contact allergy is when the immune system of your skin has a more localized allergic reaction to lettuce, often causing red, itchy patches where you have contact with lettuce.

A lettuce contact allergy was thought to be present as an occupational risk (lettuce pickers, gardeners, people with lettuce eating pets, lettuce carvers, lettuce throwers and lettuce bowling… the last 3 being made up but would be awesome jobs) but is believed to be prevalent, but under diagnosed, in a non-occupational setting.[2]

Such as eating.

If your reaction is redness, swelling, or irritation of the lips (and possibly mouth) when eating lettuce it is possible you have a contact allergy to either sesquiterpene lactone (made by the plant) or to the lettuce itself.[2,3]  The problem is how to diagnose this.  One study suggests the best method to test is to do a patch test with freshly cut lettuce stem (translation:  tape freshly cut lettuce stem to your back and keep it there for 48 hours… allergists aren’t always the best at inventing scientific procedures).

Note:  my new allergy goal is to do a lettuce patch test at some point in my career.

Salad dressing is a common cause of lettuce allergy
Dressing is a common cause of allergy. Even fancy dressings like these.

3.  Lettuce Allergy – Alternative Cause #3:  The Dressing

When I was growing up, my dad used to do three things I believed scarred me for life:  he used to drink warm water instead of coffee or tea, he used to eat dry corn flakes, and he used to eat salad with only salt and pepper.  No dressing. Nothing.  To this day, these images haunt me.

But for some of you, a salt and pepper only salad might fix your problems… if you have a hidden food allergy to an ingredient in dressing.

Salad dressings often contain common food ingredients that may not be recognized as the cause of your symptoms.  For example:

  • Ranch and other creamy dressings contain milk
  • Cesar dressing may contain milk, eggs, or fish
  • Some salad dressings contain pine nuts or tree nuts
  • Asian inspired dressings sometimes contain sesame seeds

These are just a few examples, but the salad dressing should be a usual suspect with any lettuce allergy reaction.

If you suspect a dressing, it is best to find the ingredients and write them down (or ask the chef if you’re at a restaurant) and then have an allergist do an allergy test to those ingredients to see if you react.

Allergic to lettuce is sometimes an allergy to carrots or other foods
Lettuce allergy might be due to carrots. Or tomatoes. Or the purple stuff in this one (yes, I know it’s cabbage. I just don’t acknowledge as a real food)

4.  Lettuce Allergy – Alternative Cause #4:  Carrots or other added ingredients

If your reaction happens when you eat lettuce only… then this one is less likely.  But many times lettuce, when served as a salad, might have carrots or other vegetables added.  Or some times lettuce is added to ruin a perfectly good hamburger.  If your reaction happens in these situations, then all the other ingredients are suspect.

You might be allergic to one of these other vegetables.  Oral allergy syndrome is also common with multiple different fruits and vegetables.  There is even a red meat allergy (thanks to the lone star tick… another topic you can request I write about).

Even if you don’t know of the allergy, or think it’s unlikely, you need to suspect it.  By broadening the list of possible causes, you can often find the real trigger.

Pesticide allergy is not common cause of a lettuce allergy
Pesticides are not usually the cause of lettuce allergy (pic source)

5.  Lettuce Allergy – Alternative Cause #5: Pesticides or additives

I put this possibility last for one reason:  most people THINK it’s due to a pesticide or other chemical additive when, in fact, it is one of the above causes!  The cause of allergy-type symptoms is rarely due to a pesticide when compared to the above more common possibilities.

But I cannot rule it out.

My thought is that if you buy lettuce and eat it and get lettuce allergy symptoms… but when you wash it you don’t ge the symptoms… then it might be some chemical as the cause.  If this is the case (or even if it’s not):  wash your lettuce before you eat it!

Again, it is possible your lettuce allergy symptoms are due to a pesticide/additive trigger.  But the above causes are more likely.

 

Summary

Lettuce allergy is not as common as some other food allergies, but there are people with life-threatening anaphylaxis reactions when eating their leafy greens.  If this describes you, your plan is simple:

  1. Avoid lettuce in all forms and varieties
  2. See an allergist for confirmation testing and get an injectable epinephrine pen (such as Auvi-Q)
  3. Monitor for other food allergies:  peach, tree nuts, legumes, tomatoes, cereals, mustard, melon and runner beans

For most people, though, their lettuce allergy seems to ‘come and go’ or is inconsistent… which means it is more likely not a true lettuce allergy but due to some other reaction.  There are 5 common causes of being falsely allergic to lettuce:

  1. Lettuce oral allergy syndrome (AKA pollen-food syndrome)
  2. Contact allergy to lettuce
  3. Salad dressing allergy
  4. A different food allergy (i.e. carrots, other vegetables, red meat, etc)
  5. Pesticide or chemical additive

The reason for finding the true cause is not just a ‘gee whiz’ answer or to win some allergy bingo game, but by identifying the true reason then you can avoid the trigger and not worry about any reactions!

Or, if you hate lettuce, you can still say you have a lettuce allergy and avoid it.  Just make sure you do a subtle wink whenever you say “lettuce allergy” so all the allergists in the world know you understand you don’t want to eat your greens.

 

Next Steps

If you are unsure whether your reaction is due to an allergy vs intolerance, I have written this post on food intolerance vs food allergy to help figure out your reactions.

But if you remain unsure (or want me, as an allergist, to review your symptoms and give you my best interpretation) you can click here and describe your symptoms and I’ll do my best to help you out.

And, if you enjoyed this article, why not share it with your friends?  I mean, there are so many irritating political articles being shared these days you would lighten your friend’s day if you shared something as unique as an article on lettuce allergy (maybe I’m over selling it… but I don’t think so, because where else have you read an article on lettuce allergy?!)

 

 

Sources:

  1. Muñoz-García E, Luengo-Sánchez O, Moreno-Pérez N, Cuesta-Herranz J, Pastor-Vargas C, Cardona V.  “Lettuce Allergy Is a Lipid Transfer Syndrome-Related Food Allergy With a High Risk of Severe Reactions.”  J Investig Allergol Clin Immunol. 2017;27(2):98-103.
  2. Paulsen E, Andersen KE.  “Lettuce contact allergy.” Contact Dermatitis. 2016 Feb;74(2):67-75.
  3. Paulsen E. “Systemic allergic dermatitis caused by sesquiterpene lactones.”  Contact Dermatitis. 2017 Jan;76(1):1-10.

 

 

 

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