If you have food allergies, you know the drill: Eat so much as one crumb of the offending fare, and it can feel like your immune system is preparing for the apocalypse. Cue symptoms like hives, your stomach literally cramping your style, or even more dangerous signs that your body doesn’t appreciate the culinary intruder, like trouble breathing.
But maybe your so-called food allergies aren’t what they seem. These and other symptoms could instead be a sign of histamine intolerance, a lesser-known condition that is basically a fancy way of saying you might have too much histamine—the chemical that causes allergic reactions—floating around your body.
It’s very easy to mistake symptoms of histamine intolerance for those of a food allergy, Joseph Dizon, M.D., chief of the Department of Allergy and Immunology at Kaiser Permanente West Los Angeles, tells SELF. In both cases, your body’s reacting to a surge of histamine, it’s just that the underlying mechanism is different. Confused? No worries. Here’s everything you need to know about the difference between food allergies and a histamine intolerance.
Histamine is a naturally-occurring chemical that wears many different hats, but it’s best known for its starring role in inducing allergic reactions.
Perhaps like you, histamine is big on multitasking. Stored in almost all your various tissues, histamine acts as a neurotransmitter that passes notes between your brain and body and is a component of stomach acid, helping you to break down food, Amy Shah, M.D., an Arizona-based allergy and immunology specialist, tells SELF. Your body also releases histamine when you’re injured to [promote inflammation, which helps you heal.
And, of course, histamine is a critical part of allergic reactions, including those involving food. When you eat a food that your immune system has mislabeled as dangerous, it battens down the hatches by ordering your body’s mast cells (a type of white blood cell) to release histamine and other chemicals. This is what causes symptoms like itching, swelling, congestion, hives, and even full-on anaphylaxis (a severe allergic reaction that includes potentially life-threatening effects such as your airways closing).
Because histamine plays so many different parts in how your body functions, symptoms of an intolerance are broad and can easily be confused for other things (like, you know, food allergies).
Some of the most common symptoms of histamine intolerance to be aware of include:
Abdominal cramping, bloating, diarrhea, and other gastrointestinal weirdness: Remember, histamine is important for helping you to break down food. If your body isn’t properly processing and absorbing the things you eat, you might experience symptoms like gas, bloating, diarrhea, and stomach pain.
Headaches and dizziness: Histamine may cause the blood vessels in the brain to dilate (expand). “This dilation of blood vessels is responsible for the headache, and a sensation of dizziness can also be triggered because of it,” Dr. Dizon says.
Nasal congestion, sneezing, and respiratory symptoms: When your blood vessels dilate because of excess histamine, the histamine can travel anywhere it pleases, including your nasal passageways, Dr. Shah explains. (Plus, certain areas, like your nose and mouth, already have a lot of mast cells as it is.) There, it can cause symptoms like sneezing and congestion. On a related note, histamine can affect other parts of your respiratory system beyond your nose, including your airways. In extreme cases of histamine intolerance, you may experience side effects such as trouble breathing.
Dermatological problems like rashes, eczema, and itchy skin: In the same way that excess histamine can trigger nasal drama when it travels, it can also pop up in the form of skin issues.
If someone has a histamine intolerance, symptoms can be brought on by eating histamine-rich foods or foods that allow the body to release more histamine.
First things first: A lot remains to be discovered when it comes to histamine intolerance. With that said, the prevailing theory is having too much of the chemical in your body can lead to unpleasant symptoms if you're overly sensitive to this chemical, Dr. Shah says.
This may happen if someone with a histamine intolerance eats or drinks something with a lot of histamine (which doesn’t only exist in your body, but is present in many foods and beverages, too). Symptoms of a sensitivity might happen if your tolerance level for histamine is naturally low and you have a helping of a high-histamine food or beverage, Johane Filemon, R.D.N., an Atlanta-based dietitian specializing in food intolerances and anti-inflammatory diets, tells SELF.
The biggest offenders, according to a review published in The American Journal of Clinical Nutrition, are fermented foods and drinks such as aged cheeses, yogurt, kefir, sauerkraut, processed meats (or meats that aren’t super-fresh), and alcoholic drinks (sob)—especially wine, champagne, and beer. This is because histamine levels increase with maturation. Some vegetables, like eggplant, are also considered more histamine-rich than others, but the general rule is that the less processed the food, the less likely it is to have as much histamine. There’s also a theory that some foods are “histamine liberators,” meaning they’re not histamine-rich themselves, but they can trigger the body’s cells to release histamine, Dr. Dizon says. These foods might include citrus fruit, strawberries, nuts, and chocolate, among others, though more studies need to be done before researchers can confirm this hypothesis.
Another possibility is that you may experience symptoms of histamine intolerance if something is preventing your body from processing the chemical as seamlessly as usual.
One notion is that this may happen if enzymes that are supposed to break down excess histamine in your body aren’t as active as they should be, Dr. Shah says.
DAO (street name: diamine oxidase) is the main enzyme that helps the body metabolize the histamine found in foods. DAO is produced in the musoca of your small intestine, from which it eventually makes its way into your blood. Although there’s not a conclusive link between lowered DAO and histamine intolerance, it’s a prevalent theory, one that may implicate gastrointestinal disorders as a risk factor for this sensitivity.
If your gut isn’t working properly—say, because of a disorder like irritable bowel syndrome (IBS) or an inflammatory bowel disease such as ulcerative colitis or Crohn’s disease—this could increase the odds that your DAO production may be out of whack, too. Chronic inflammation in the digestive system may trigger a one-two punch of elevating histamine and diluting DAO activity, Filemon explains.
Some evidence also suggests that agents in certain medications (such as nonsteroidal anti-inflammatory drugs, some tricyclic antidepressants, and antibiotics), can block DAO from doing its thing or prevent production of the enzyme, which might cause an uptick in histamine levels in the body. Again, more research is needed to validate these claims.
Also, weird fact: Histamine intolerance may be able to trigger worse period symptoms, like cramping. It might also get better during pregnancy.
It seems as though histamine may stimulate the synthesis of a form of estrogen called estradiol, which can then prompt production of prostaglandins, hormone-like chemicals that can lead to that heinous uterine cramping. Conversely, estradiol may also be able to stimulate mast cells to activate and release histamine more easily, Dr. Shah says, so this could be a cycle of sorts. (You’ve probably picked up on this pattern by now, but we’re going to reiterate that this isn’t set in scientific stone.)
On the flipside, in pregnant people, DAO concentration typically skyrockets by 500 times thanks to the placenta, which churns out large amounts of the chemical because it can play an important role in processes like cell growth. This could help explain why histamine intolerance symptoms seem to diminish during pregnancy for some people.
The main way to tell the difference between a food allergy and histamine intolerance is that the former is typically much more consistent than the latter. It can also be more dangerous.
When you have a food allergy, your body will always react to eating that food, often with symptoms striking very shortly after you eat it, Filemon says. When your immune system has labeled the food (or a substance it contains) as harmful, even a teensy amount can trigger an allergic reaction, the Mayo Clinic explains.
Histamine intolerance won’t necessarily cause symptoms every time you eat certain foods. The levels of this chemical can vary, even in the same type or brand of food, depending on factors like how the food was harvested, processed, and stored, Filemon explains. You might eat a helping of your favorite cheese one day and feel fine, but the next time feel congested because of how factors like these can affect your snack.
Researchers are also still investigating to what extent cooking methods may cause histamine levels in foods to increase or decrease. “This makes it hard to come up with a list that can state the exact levels of histamine in foods,” Filemon says.
Also, remember, whether or not you experience histamine intolerance symptoms can hinge on how well your body is processing the amount of histamine already in your system, which can change depending on the aforementioned factors, like certain drugs and pregnancy.
Finally, while histamine intolerance might cause similar symptoms as a food allergy, it will usually do so to a lesser extent. Food allergies can be life-threatening; food intolerances are typically not as severe.
Cutting back on foods and drinks that are high in histamine may help alleviate symptoms if you do so under medical guidance, but there’s no scientific proof that a low-histamine diet is the answer for everyone.
Unlike food allergies, where steering clear of whatever your immune system has blacklisted is a no-brainer, reducing histamine intolerance symptoms isn’t as clear-cut. It might seem as though, if you suspect you have a histamine intolerance, you should just immediately forsake any food researchers believe is typically high-histamine. Don’t do this. “It’s a very restrictive diet,” Nicholas Hartog, M.D., an allergy and immunology specialist at Spectrum Health in Grand Rapids, Michigan, tells SELF. Attempting this sans guidance from a medical professional could potentially make it harder to meet your nutritional requirements (or just lead you to needlessly cut out things from your diet that you enjoy).
If you think you might be dealing with histamine intolerance, keep a food journal for a few weeks and share your intel with an allergist. Take note of what you eat and drink, along with any symptoms that follow, Dr. Shah suggests. Bring your data to an allergist, who can use it to help you put together a game plan. (Even if you don’t have histamine intolerance, the diary can point your medical provider in the right direction to make a different diagnosis.)
No diagnostic test exists specifically for histamine intolerance, but that doesn’t mean you can’t find some relief from your symptoms if that’s what you have.
There’s not a reliable lab test or procedure available that can provide a firm histamine intolerance diagnosis, Dr. Shah says. In general, you’ll need to experience at least two or more typical histamine intolerance symptoms, and your doctor will need to rule out any other potential causes. They might do this by performing a skin-prick allergy test to see if you do, in fact, have a food allergy, or they may try to test your DAO levels and measure how much histamine is in your blood plasma. However, because these tests can’t definitively diagnose an intolerance, the results will be considered in conjunction with your food diary, health history, and any other data your doctor can collect.
From there, your doctor can help you pinpoint the treatment options that might work best for your apparent particular histamine threshold, Dr. Shah says. This may include moves like avoiding (or cutting back on) any foods you’ve found are most likely to trigger your symptoms and eating super-fresh ingredients as often as possible. Your doctor may even recommend you take a DAO enzyme supplement (along with other supplements that might make it work better, such as vitamins C and B6). Whether or not you actually have histamine intolerance, talking all of this through with your doctor can help optimize your nutrition, minimize your symptoms, and leave you feeling a whole lot better.