Severe Vomiting After Shrimp Could Be Food Allergies

Have you ever had an amazing shrimp dinner, gone home or back to your hotel, and then started getting nauseous and vomiting all night long? Maybe you’re here because it’s the first time it’s happened and you just got a bad batch of shrimp. Or, maybe you’re here because it’s happened once or twice before, and you’ve narrowed the culprit down to some sort of fish or shellfish. It could have been an unlucky case of food poisoning, or it could be something a little more unusual.

Delayed vomiting is a classic symptom of FPIES, (Food Protein-Induced Enterocolitis Syndrome) and fish and shellfish are some of the top foods that cause an FPIES reaction for adults later in life. Always check with your doctor, because they can rule out a ton of other diseases and conditions that have these same common symptoms. But, if they check you out and rule out all of the other stuff, and you are still having repetitive, delayed vomiting after eating shellfish, you may want to ask your doctor about an FPIES diagnosis. 

Now, here’s my disclaimer – I’m not a doctor, and I don’t have medical training. But I do have first hand experience with FPIES reactions, because my two kids have this type of rare food allergy and we’ve been managing it for six years now.

What is FPIES Anyway?

By this point you are probably wondering what the heck FPIES is. It stands for Food Protein-Induced Enterocolitis, and it’s a type of rare food allergy that affects babies and even adults. FPIES is a non-IgE mediated food allergy, which means reactions don’t look the same way they would for someone who gets hives and throat swelling from shrimp or peanuts. Instead, FPIES mainly affects the GI tract, causing nausea and vomiting, extreme stomach cramps, and diarrhea. 

The most common sign of FPIES is delayed vomiting, often somewhere between 2-4 hours after you’ve eaten the food that triggers a reaction. For adults, fish and shellfish are the most common trigger foods. For babies with FPIES, there are many potential trigger foods, although many babies only have only one or two foods they react to. Be sure to check out this post for a large list of common foods to watch out for.

How is FPIES Diagnosed?

Because FPIES symptoms overlap with symptoms of food poisoning and many common viruses, it can sometimes take a while to get an FPIES diagnosis. It’s often misdiagnosed as food poisoning, because most patients recover quickly with fluids and Ondansetron.

To make things more complicated, FPIES doesn’t show up on typical skin prick tests for IgE allergies, and there is no test specifically designed to show FPIES. 

FPIES is usually diagnosed through a process of elimination (making sure symptoms aren’t from another disease or virus that can be ruled out). Sometimes doctors will do an oral food challenge in an office or hospital. This involves giving small amounts of the food that has caused reactions in the past and watching for a reaction in a setting where the patient can be monitored. In some cases, doctors will make a diagnosis after just listening to a patient’s history and ruling out other conditions that could be causing the symptoms. 

In the peer reviewed studies done on adults with FPIES, participants needed to have a similar reaction to the same food on 2-3 separate occasions in order for it to be considered an FPIES trigger. Interestingly, the adults in these studies were all different ages when they had their first FPIES reaction, with the average age being 34. These adults also had reactions at different time intervals after they ate the trigger food, ranging from 3 minutes to 6.5 hours later. Many of the adults said their reactions happened out of nowhere, and some had been eating shellfish their whole lives with no issues.

If It’s FPIES, How is It Treated?

The very best treatment for FPIES is identifying and avoiding the trigger foods. This is another area where things are going to be different for adults than it will be for children. There is currently no evidence of adults “outgrowing” FPIES, but many kids do outgrow their inability to eat certain foods. For adults who develop repeated vomiting after eating shellfish, avoiding shellfish would be the best way to treat the allergy. Check with your doctor about treatment options if you are accidentally exposed to the food.

There is some evidence to suggest that Zofran works for adults like it does for children, but there needs to be more research on adults with FPIES because right now it’s just so limited. Some doctors also prescribe Epi-Pens for people with FPIES to shellfish because there is some overlap between IgE and non-IgE mediated allergies. 

If you think you may have experienced FPIES like reactions, ask your doctor about FPIES. They will be able to do allergy testing and rule out many other common conditions that can cause similar symptoms. Besides, it’s always good to have a treatment plan and any necessary medicines on hand in case you are exposed to the food again. Even the most careful person with food allergies gets exposed accidentally at some point in their lives, so it’s good to be prepared.

What to do if you’re already sick from shellfish

The best thing to do is try to stay hydrated. Dehydration is one of the biggest risk factors with FPIES, and it can happen quickly because the amount and speed of vomiting can be intense. If you can’t keep anything down and feel like you are getting dehydrated, it’s probably time to head in to the doctor or to your local emergency room for IV fluids. They can also give you a medicine like Zofran or Ondansetron to stop the vomiting. Your doctor may even prescribe some for your house if you have reactions often, just follow their dosing instructions and advice.

The agonizing thing about FPIES is that there’s no magic medicine that prevents it. Vomiting is the body’s way of getting rid of viruses or food that’s contaminated. Unfortunately, for people with FPIES, their bodies often see normal food as a threat, and their immune system goes into action to get rid of the threat. For my kids, I’ve learned that once they start throwing up, their body has to get it all out. This is gross, so consider yourself warned; once they get to the point of dry heaving and there’s nothing left, or in severe reactions if they start throwing up bile, then it’s time for us to head to the ER and get treatment. I’ve found that for reactions that aren’t so severe, once they’ve thrown up all of the food that’s making them sick, the reaction will usually pass on its own.

It’s hard to go through that or watch your child go through that and not be able to help, so we do spend more time watching comforting shows on the couch, taking baths with Epsom salts, and drinking plenty of fluids and resting after a reaction. Do what you need to and take it easy for a bit, and watch out for those pesky trigger foods.


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