What is histamine intolerance and histamine? If you're not sure, or if you want to know more about it, this definitive science-backed guide will help. We'll go over what histamine is, how our bodies break it down, histamine intolerance, symptoms, causes and much more. By the end, you'll know everything you need to know about histamine, and you should have a good understanding of whether or not you have histamine intolerance.
Contents:What is Histamine Intolerance How Do We Break Down Histamine What is Histamine Intolerance Histamine Intolerance Symptoms Histamine Intolerance Causes Histamine Intolerance Tests Histamine Intolerance Treatment Histamine Intolerance Supplements Bonus Content: Probiotics for Histamine Intolerance Bonus Content: Histamine Intolerance Food List Final Thoughts on Histamine Intolerance
What Is Histamine?Simply put, histamine is a chemical compound that is naturally found in a lot of cells in your body. Histamine is responsible for common allergy symptoms, such as itchy and watery eyes, sneezing, congestion, and runny nose. When you have an allergic reaction to something, your immune system mistakes a harmless substance as a threat, and it overreacts. This in turn triggers a domino effect throughout your body, and your immune system prompts your cells to release histamine into your body, resulting in an allergic reaction. As histamine floods your nose, eyes, skin, lungs, and gastrointestinal tract, you'll have a sudden onset of the common allergy symptoms we listed earlier.
How Do We Break Down Histamine?Since histamine acts as a neurotransmitter, its main role is to relay important messages between your body and your brain. It also works to prompt an immediate inflammatory response to a perceived threat. Although it's most common in the immune system, it can also affect your gastrointestinal tract because it helps your body break down food as well. Once your body releases the histamine into your bloodstream, enzymes will eventually break it down, or it'll get absorbed into your cells and stay stored until your body signals that it needs it again. You start to have problems when your body can't or won't break down the excess histamine in your system. When this happens, it starts to build up throughout your body. This excess histamine buildup can lead to histamine intolerance.
What Is Histamine Intolerance?When most people think of histamine intolerance, they think of someone who is too sensitive to histamine. However, this isn't true. Histamine intolerance refers to a condition where you have too much histamine in your body, and your body doesn't break it down or store it like it's supposed to. Histamine intolerance is rare, and it's estimated that it only impacts around 1 per cent of the population. A lot of people with histamine intolerance don't even realise that they have it, and it's common for them to mistake their intolerance for other medical conditions, such as gastrointestinal issues or food allergies. It takes specific tests to find out if you have histamine intolerance or not, and some of them can be a longer process than most people are willing to go through. However, there are several symptoms you want to watch for.
Histamine Intolerance SymptomsHistamine intolerance symptoms can vary from person to person, and they can also vary in their severity levels. This is part of the reason why people tend to misdiagnose their histamine intolerance as something else and not get definitive testing done to rule it out. Common histamine intolerance symptoms include: Cardiovascular System:
- Arrhythmia (Accelerated heart rate)
- Fast beating
- Low blood pressure
- High blood pressure
- Vertigo (dizziness)
- Trouble regulating body temperature (fever or chills)
- Abdominal cramping
- Heartburn, or acid reflux
- Excessive flatulence
- Constipation (rare)
- Concentration trouble
- Mood swings
- Runny nose
- Difficulty breathing
- Chronic sinus infections
- Persistent cough
- Rash or hives
- Inflamed patches of skin
- Swelling (face, hips, and hands)
- Headaches or migraines
- Trouble falling and staying asleep
- Abnormal menstrual cycle
- Fatigue or lethargy
- Joint pain
- Autoimmune conditions
- Alcohol or wine intolerance
- Itchy throat
- Watery or itchy eyes
- Oedema (swelling around the eyes, throat, and mouth)
Histamine Intolerance CausesWhile there are several factors that may lead to histamine intolerance, it's important for you to understand why and how they can cause an intolerance. Gene mutations are classified as a permanent alteration of the DNA sequence that forms the gene. These mutations range in size from a single base pair of a DNA building block to a large segment. Gene mutations are put into two broad categories:
- Hereditary — Hereditary gene mutations come from your parents, and you can find this mutation in almost every cell in your body. They're present in a person throughout their lives as well. People also refer to them as germline mutations because you find this mutation in the parent's sperm cells or eggs. When an egg gets fertilised, it gets DNA from both sets of parents, and this is where the mutation takes hold and grows in each of the child's cells.
- Somatic (Acquired) — Somatic or acquired gene mutations appear in certain cells in your body at different stages during your life, and they can be present in every cell of your body except the sperm and egg cells. This means that you won't pass them on to your children. Environmental factors like ultraviolet radiation can cause somatic mutations to occur, and they may also appear during cell division as a result of an error occurring when your DNA copies itself.
- DAO — The DAO gene stands for Diamine Oxidase. Its main function is to help regulate the levels of the neuromodulator D-serine in your brain. The DAO gene helps circulate histamine throughout your system, and the DAO enzyme also breaks down histamine. When you have a mutation of this gene, the enzymes that break down the histamine in your system are significantly lower. The enzymes can't keep up with the histamine levels, and they start to build up.
- HNMT — The HNMT gene refers to Histamine N-methyltransferase. This is the gene that is largely responsible for metabolising the histamine present in your body. It also helps to control neurotransmitter activity that is centered around histamine production, which can make the histamine in your system inactive. When this gene mutates, it stops regulating the production or active status of histamine, and it also doesn't metabolise it as effectively. It can lead to an overproduction of histamine that builds up in your system.
- Monoamine Oxidase — Monoamine Oxidase isn't a gene, but a family of enzymes that play an important role in triggering the HNMT gene to metabolise and regulate histamine. In a non-mutated enzyme, this means that your body will metabolise the histamine and won't allow it to build up. However, when it has a mutation, your body isn't able to break down histamine as quickly as it needs to, and this leads to histamine intolerance.
- MTHFR — MTHFR, or Methylenetetrahydrofolate reductase, is another enzyme that encodes itself into the MTHFR gene, and it helps to regulate histamine production. It also plays a role in processing amino acids throughout your body. When your MTHFR gene mutates, it disrupts the production of the MTHFR enzyme. This sets off a chain reaction that disrupts and alters methylation. As a result, your histamine levels rise because they're directly linked to how well your methylation functions.
2. Diamine Oxidase (DAO) DeficiencyAnother cause for histamine intolerance is Diamine Oxidase (DAO) deficiency, and one study estimated that having this deficiency accounts for 70% of all histamine intolerance cases. When you have this deficiency, there is a disruption in how efficiently the DAO enzyme breaks down food-based histamine in your digestive tract due to low DAO enzyme activity. You'll find the DAO enzyme in your digestive system, and your intestines are responsible for producing it. The DAO enzyme thrives in your intestinal mucosa. If this goes untreated, you'll get an imbalance of the histamine that your cells release and the histamine that comes from food in your system. This imbalance leads to histamine buildup in your system. There are several common causes for DAO deficiency, and they include:
- Genetics — It's possible to inherit the genetic mutation that leads to DAO deficiency.
- Medications — Certain medications can cause a DAO deficiency including prescription and over-the-counter medications.
- Hormones — If you have a hormonal imbalance, this can disrupt how much DAO enzyme your body produces.
- Gastrointestinal Disorders — Many people with gastrointestinal disorders, such as Celiac disease, IBS, and small intestine bacteria overgrowth (SIBO), have DAO deficiency because the inflammation can disrupt how well your intestinal lining produces this enzyme.
3. Small Intestine Bacterial Overgrowth (SIBO)SIBO, or Small Intestine Bacterial Overgrowth, is a medical condition where you have excessive amounts of bacteria in your small intestine. An excessive amount of bacteria means that you have over 100,000 bacteria for every mL of fluid. These bacteria can take over and have a negative impact on how well your small intestine breaks down and absorbs the nutrients in your food, as well as food-based histamine. Additionally, the bacteria can actually produce more histamine. When you combine these two factors, you get a combination that allows histamine to start to build up in your body. The histamine levels can overwhelm the DAO enzymes that are present in your small intestine, and the histamine can cycle through your body and into your organs. When this happens, you get the classic symptoms of histamine intolerance including headache and changes in your mood.
4. Candida OvergrowthDid you know that there are over 20 different Candida yeast species that are capable of overgrowing in your digestive tract and causing an infection? In healthy amounts, Candida helps break down food in your intestines and it helps your body absorb nutrients, minerals, and food-based histamine. Candida overgrowth is often linked to histamine intolerance. When you have Candida overgrowth, you typically have inflammation as well, and your body will release histamine in response to the infection or perceived threat. The inflammation can also cause DAO enzymes to decrease, and this means that they'll quickly get overwhelmed by the influx of histamine. Also, Candida and certain types of fungus can release a form of alcohol into your bloodstream, and this can aggravate your histamine intolerance. The yeast ferments sugars in your diet and turns them into alcohol. This is what gets into your bloodstream, and it reduces how effective DAO enzymes are.
5. Leaky Gut SyndromeMany people use leaky gut syndrome to describe a broad range of gastrointestinal conditions and issues. However, at its core, leaky gut syndrome refers to a medical condition where your intestinal walls allow toxins, microbes, and gluten to pass through into your bloodstream. You may also have heard people call it intestinal permeability, and it has links to histamine intolerance. When you have a leaky gut, you usually have a bacterial imbalance in your GI tract. Studies show that this imbalance can prompt the bacteria in your gut to release histamine. Since leaky gut allows toxins into your system, it's considered by your body to be an infection. Your body sends an inflammatory response to your gut in response, and this inflammation disrupts DAO enzymes. When this happens, the DAO enzymes have difficulty breaking down the histamine present in your GI tract. They can't keep up with the demand, and the histamine will eventually get into your bloodstream through your weakened intestinal wall and circulate through your body.
6. Histamine-Rich DietEating a diet with histamine-rich foods can cause your histamine intolerance symptoms to flare, or cause histamine intolerance. If you already have higher levels of histamine in your body, or if your body is having trouble processing histamine, adding histamine-rich foods can overload your system. Additionally, certain foods can trigger your cells to release histamine and there are foods that block DAO enzymes. If you incorporate all of these into your diet, you can quickly develop histamine intolerance because the DAO enzymes that are available to help metabolise the histamine in your system won't be able to keep up. As such, histamine will continue to build up in your system to unhealthy levels. Histamine-rich foods include:
- Canned food
- Processed foods
- Fermented foods
- Citrus fruits (lime, plums, lemon, kiwi, and oranges)
- Energy drinks
7. MedicationsBoth prescription and over-the-counter medications can cause histamine intolerance because of their active ingredients. Some ingredients in medications encourage your body to release histamine (histamine liberators), and other ingredients can negatively impact DAO enzymes (DAO blockers). Of course before considering adding or removing medication from your regime always consult with your health care professional. DAO enzyme blocking medications include:
- Acetylcysteine — You can get Acetylcysteine as a prescription medication or on an over-the-counter basis. It's a cough medicine that helps loosen the mucus you may have in your airways. It also comes in a topical form to treat skin infections and rashes.
- Aspirin — Aspirin is available without a prescription. This medication is an NSAID (nonsteroidal anti-inflammatory drug) that you use to relieve mild pain, headache, fever, and mild inflammation.
- Ambroxol — For people with chronic respiratory conditions that produce a lot of phlegm, Ambroxol can work to break it up. This allows you to be able to take a deep breath and breathe easier.
- Aminophylline — You can use Aminophylline to treat respiratory tract inflammation. You will need a prescription to get this medication, but it helps to prevent wheezing, shortness of breath, and difficulty breathing.
- Amiloride — Amiloride is a diuretic that people use to treat high blood pressure, congestive heart failure, and low potassium levels in the blood. Your doctor will prescribe this medication for you.
- Amitryptiline — Doctors prescribe Amitryptiline to treat and relieve symptoms of depression and nerve pain. It also helps to treat anxiety, bipolar disorder, and ADHD when you take it as prescribed.
- Cefuroxime — If you have a bacterial infection, your doctor may write you a prescription for the antibiotic Cefuroxime. It works well with UTIs, sinus infections, bronchitis, otitis media, and Lyme disease.
- Cefotiam — Another antibiotic that works well against a broad range of bacterial infections is called Cefotiam. Your doctor will commonly prescribe it for you if you have more severe infections — for example, Staphylococcus or skin infections.
- Cimetidine — You can get generic versions of Cimetidine without a prescription. However, a prescription is required if you want stronger drugs. Cimetidine is used to treat acid reflux as it inhibits the production of stomach acid.
- Ciprofloxacin — Another powerful antibiotic, Ciproflaxcin is commonly used to alleviate bacterial infections. Your doctor must prescribe this antibiotic, and it works on bone or joint infections, skin infections, UTIs, respiratory infections, and more.
- Cyclophosphamide — For people undergoing chemotherapy, it's common to have a prescription for Cyclophosphamide. This drug will help treat cancer, and it suppresses your immune system.
- Contrast Media — Contrast Media is prescribed by a doctor, and you typically see people drink it before they have certain radiography procedures like MRIs or CT scans. It helps to improve the visibility of these scans.
- Diazepam — Diazepam is a controlled medication that people get from their doctors to treat anxiety, seizures, and muscle spasms. When you take this medication, it produces a calming effect.
- Haldol — Certain mental illnesses respond favourably to Haldol. This antipsychotic medication needs a prescription, and it's commonly used to help control the symptoms of schizophrenia, Tourette's, and severe adolescent behavioural problems and disorders.
- Metamizole — Metamizole is a medication you can find used in both veterinary and human medicine. You need a prescription to get this medication, and it helps to treat migraines, cancer pains, and postoperative pain.
- Metoclopramide — Metoclopramide is another medication that your doctor can prescribe if you have chronic acid reflux, also known as GERD. It also helps to prevent nausea or vomiting by stimulating the muscles in your GI tract.
- Naproxen — Naproxen is an NSAID that you can purchase over the counter. It's very popular, and people use it to treat muscle pain, swelling, stiffness, fever, and mild inflammation.
- Noscapine — You can purchase Noscapine over the counter without a prescription, but there are also stronger variants that need a prescription. This drug works to suppress coughs.
- Pancuronium — Your doctor will administer Pancuronium as an injection into your muscle to relax it and help treat strains or chronic pain. It's also the second of three drugs commonly administered during lethal injection.
- Prilocaine — Prilocaine is a popular numbing agent that you can get as a cream for topical applications or by prescription for general pain relief during and after medical procedures, such as tooth extractions.
- Thiopental — Your doctor has to order Thiopental, and it's an extremely fast-acting barbiturate that is commonly used to relax you before you have anesthesia.
- Verapamil — Verapamil needs a prescription before you're able to get it. It's a calcium channel blocker that doctors commonly prescribe to treat severe angina and high blood pressure.
- Amphetamine — Your doctor has to prescribe you amphetamine. It's a central nervous system stimulant, and it's commonly used to help treat obesity, narcolepsy, and ADHD.
- Codeine — Codeine is a narcotic pain reliever that needs a prescription. You would typically get this opiate for cough, diarrhoea, and mild to moderate pain.
- Diclofenac — For people with arthritis, or for people who routinely experience mild to moderate pain and inflammation, your doctor may prescribe diclofenac.
- Hydralazine — You'll need a prescription to get hydralazine, but it's a popular vasodilator that is effective at treating heart failure and high blood pressure.
- Levofloxacin — Levofloxacin is a powerful antibiotic that is commonly prescribed to help treat bacterial infections.
Histamine Intolerance Tests to Ask Your Doctor ForNow that you know a little about the different medications that can have an impact on your histamine intolerance, we'll give you several tests that you can ask your doctor to administer. However, histamine intolerance can be very difficult to test for, and the most popular test is also one of the most involved.
1. Elimination DietThe first thing that you have to understand is that the elimination diet is split into two parts, and it takes between five and six weeks from start to finish. You remove foods from your diet that you think may cause your histamine intolerance, and then you reintroduce them one by one and monitor your symptoms. It's very important that you talk to your doctor if you plan to do this on your own instead of with their help. They'll be able to give you great recommendations on foods to cut out of your diet as well as a step-by-step elimination diet plan.
Elimination Phase — The first step of this diet is the elimination phase. You decide which foods you think may trigger your histamine intolerance, and you remove them from your diet for two or three weeks. If you're not sure, you can also look at our histamine intolerance foods list and take away foods that are notorious for causing uncomfortable symptoms, including (you can find a full histamine intolerance food list at the bottom of this page):
- Citrus fruits (lemon, lime, oranges etc)
- Nightshade vegetables (tomatoes, eggplant, white potatoes, and peppers)
- Processed meat and fish
- Fats (butter, oils, margarine)
- Condiments and spices (relish, mustard, mayonnaise, and paprika)
- Beverages (alcohol, black tea, coffee, soda)
- Sugar and sweets
Reintroduction Phase — After you removed your foods for a week or two, you can slowly start reintroducing them back into your diet. You'll reintroduce them one by one over two or three days apiece and watch for any symptoms. If you start having symptoms, you've most likely found the cause of your histamine intolerance. Common symptoms you want to watch for include:
- Joint pain
- Rashes or skin problems
- GI issues (bloating, cramping, or pain)
- Difficulty sleeping
2. Blood Testing and the Finger Prick TestAlthough there isn't a lot of evidence to support how effective a blood test for histamine intolerance is, it can show you the ratio of histamine to DAO enzymes that are present in your body. Your doctor will draw your blood and analyse it for histamine and DAO enzyme levels. If they find that you have a high level of histamines compared to your DAO levels, it's usually a good indicator that you have histamine intolerance. They may take these results and suggest that you take a DAO supplement to help balance the ratio of histamine to DAO out. Another blood test your doctor can perform is called a finger prick test. One study took 156 participants and pricked their skin. They then applied a 1 per cent histamine solution and monitored the participants. For the participants who suspected that they had histamine intolerance, the prick test showed positive results for 79 per cent of the participants. They ended up with a small, red, and itchy bump on the pricked skin that didn't go away after an hour.
3. DAO Enzyme TrialsIf you don't want to get a blood test, or if you don't have the time to go through the elimination diet, there are other options available for you. You can choose to do a DAO enzyme trial. To do this, you simply switch your eating habits to a diet that compromises mostly of low-histamine foods and add a DAO enzyme supplement after each meal. We'll go more in depth on this trial and low histamine diets below, but if you try this and your symptoms go away, you could have low DAO enzymes.
Histamine Intolerance TreatmentOnce you're relatively sure that you have histamine intolerance, you can start deciding on how you want to treat it. There are a few things you want to keep in mind before you choose one histamine intolerance treatment because different people respond to different treatments in different ways. Simply put, what works for somebody else may not work for you.
Identifying the CauseOne of the single most important histamine intolerance treatments is to properly identify what is causing your histamine intolerance in the first place. While it is good to treat your histamine intolerance with diet and food choices, it doesn't treat the root cause. Identifying the root cause of your histamine intolerance allows you to tailor a treatment plan that suits your needs. A lot of the time, histamine intolerance comes from having poor health in your GI tract caused by conditions like leaky gut, Candida overgrowth, gluten intolerance, and SIBO. You want to find the cause and follow our outlined protocol at the same time to maximise your end results.
Histamine Intolerance DietHaving a diet plan in place for histamine intolerance sounds easy in theory, but if you don't know which foods to eat and which to avoid, it can be extremely difficult to get an effective plan in place. You can find a full histamine intolerance food list at the bottom of this post.
What Makes Foods High or Low in Their Histamine ContentWhen it comes to deciding which foods have high or low histamine content, it gets tricky. You have to understand that for the most part, the histamine content in your food isn't directly from the food. Instead, the histamine content comes from the bacteria that is in the food. The bacteria in the food naturally produce histamine because this is how they start the metabolic process. So, with this in mind, it makes sense that fresh and unprocessed foods typically have lower histamine content. On the other end of the spectrum, fermented or aged foods have higher histamine content because the bacteria has more time to release histamine. You want to avoid things like processed, smoked, canned, or fermented foods when you're on a histamine intolerance diet. Fresh food that doesn't have a long aging process or that hasn't been processed is better. Another category of foods that you may want to avoid are foods that prompt your body to release histamine. They don't necessarily contain histamine on their own, but when they get in your body, they cause stored histamine to be released. Certain citrus fruits, meat, and protein sources are examples of these foods.
Histamine Intolerance SupplementsIf you can't pinpoint what is causing the histamine levels in your body to rise, you can try taking histamine intolerance supplements. These histamine intolerance supplements can help you get relief from your symptoms and balance your body's histamine levels.
1. DAO EnzymeIf your DAO enzymes are low or if something disrupts them, it can cause a histamine imbalance. Taking DAO enzyme supplements is one way to increase your DAO enzyme levels in your digestive tract. In turn, these enzymes will be able to break down the histamine every time you eat something. However, a DAO enzyme supplement will only work on the histamine in your digestive tract, and it won't spread to your bloodstream on its own. You can boost your DAO enzyme levels by taking the supplement with several key nutrients, including:
- Omega-3 fatty acids
- Saturated fats
2. Digestive EnzymesYour digestive enzymes help to break down all of the food you eat, and when they're not in balance, they have trouble breaking down histamine and absorbing it into your body. Adding a digestive enzyme supplement to your diet can help rebalance your DAO levels, rebalance your bacteria levels, and reduce your histamine levels. You can find a good digestive enzyme here.
3. Vitamin CAnother way to boost your DAO levels is to take a vitamin C supplement. A vitamin C supplement can boost your natural levels of DOA because it has powerful anti-inflammatory properties as well as antioxidant properties. As the inflammation in your body goes down, your DAO enzymes will be able to work at their optimal levels. Vitamin C also helps to jump-start the DAO enzyme production process, and it also acts as a natural antihistamine.
4. QuercetinQuercetin is a natural pigment that is found in plants, and it has powerful anti-inflammatory properties. When you take a Quercetin supplement, the Quercetin goes straight to the cells that store the histamine. Once it gets to these cells, it starts to block the mast cells from releasing their histamine content.
5. BromelainBromelain is a protein-digesting enzyme that can be found in pineapple stems. This enzyme has a long history of medicinal use, and it has recently started gaining attention as a histamine intolerance supplement. Bromelain has antihistamine properties, and it can also improve how well your body digests nutrients, vitamins, minerals, and enzymes.
6. Urtica DioicaUrtica Dioica is the scientific name for nettles, or stinging nettle. There are several studies that support the anti-allergen properties of this plant, as well as its high levels of serotonin. These antihistamine properties can safely and naturally lower the histamine levels in your body. It can also help regulate your immune response, and this can reduce your symptoms.
7. N-acetyl cysteineA N-acetyl cysteine supplement can have a positive effect on your histamine intolerance. When you take it, it works to maximise the effects of any other supplement that you take to help with your histamine intolerance. This means that it goes directly to the root of this condition instead of treating only the symptoms, which makes it a powerful supplement.
8. SAM-eSAM-e is a naturally-occurring molecule in your body, and it's also a popular supplement that helps with histamine intolerance. It's a key component in breaking down other chemicals, enzymes, or molecules in your body. Sam-e works to deactivate the histamine in your body, and this lowers your overall levels and makes them more manageable for your DAO enzymes.
Bonus Content: Probiotics for Histamine IntoleranceDid you know that probiotics can also help with your histamine intolerance? We're going to give you three different probiotics that work to break down histamine quickly and effectively.
- The final probiotic on our list is Lactobacillus Plantarum. This probiotic also has powerful histamine degradation properties. One study showed that it gets into your system and begins to break down histamine on a molecular level. This decreases the levels of histamine in your body, and this includes your GI tract as well as your blood. You can find a good quality probiotic with this strain plus two others which are good for histamine intolerance here.
- This probiotic doesn't break down histamine, but it has antihistamine properties. Instead, it focuses on regulating your immune system's reaction that sets off histamine production. One study showed that taking this probiotic decreased how much histamine your immune system creates in response to a perceived threat. This can reduce your symptoms and the levels of histamine in your blood.
- This probiotic is instrumental in histamine degradation. It enhances genes that are responsible for tight junctions, and this decreases intestinal permeability. It turn, your inflammation levels go down, and this can cause your DAO enzymes to function at higher levels. This has the potential to make your histamine intolerance symptoms go away.