Histamine Guide: Allergies, Antihistamines, and MORE!
- Natalie Wescott
- Sep 23
- 12 min read
Allergy season hits and suddenly half your family is sneezing, itching, or dealing with watery eyes. The first instinct is usually to grab a pink Benadryl or a “non-drowsy” allergy pill. But have you ever wondered what histamine actually is, why your body reacts the way it does, and whether there are safer, more holistic options to calm the storm?
This post breaks it all down, from what histamine does in the body, to the stages of the allergy cascade, to pharmaceutical vs. holistic treatments, histamine intolerance and MCAS, specific product recommendations, and what to do in a true emergency like anaphylaxis.
As always, this is not medical advice, just information for personal education!
This guide is by no means comprehensive.
What Is Histamine?
Histamine is a natural chemical messenger your body uses every single day. It’s stored in mast cells and basophils (immune cells), and it serves several important functions:
Immune defense: In infections or injury, histamine makes blood vessels leaky so white blood cells can reach the problem area.
Stomach acid regulation: It stimulates stomach cells to release acid for digestion.
Brain function: Histamine is a neurotransmitter that helps regulate wakefulness, learning, and appetite.
Wound healing: By opening blood vessels, histamine brings nutrients and immune factors to tissues that need repair.
Histamine itself is not “bad.” The problem comes when your body misfires and releases histamine against harmless substances like pollen, dust, pets, or certain foods. That’s when you experience an allergic reaction.
The Allergy Cascade
Allergic reactions unfold in three main stages: sensitization, histamine release, and inflammation
Stage 1: Sensitization
The first time you’re exposed to something like ragweed pollen, your immune system makes IgE antibodies.
These antibodies “sit” on mast cells like loaded weapons.
You may not feel symptoms yet, but your immune system is primed.
Conventional care: Nothing is done at this stage.
Holistic care: Root-cause support matters here: gut health, reducing toxin exposure, and lowering chronic inflammation.
Stage 2: Histamine Release
On re-exposure, allergens bind IgE on mast cells → histamine is released.
This causes itching, sneezing, watery eyes, runny nose, hives, and swelling.
Conventional treatment: Antihistamines
First-generation (diphenhydramine/Benadryl, hydroxyzine, chlorpheniramine) cross into the brain and cause sedation, cognitive impairment, and paradoxical agitation in some kids. A 2024 study found a 22% increased seizure risk in toddlers with first-gen antihistamines (Kim et al., 2024).
Second-generation (cetirizine, loratadine, fexofenadine, levocetirizine, desloratadine) are much less sedating and safer for daily use, but does not come without risks,
Holistic alternatives:
Quercetin
What it is: A flavonoid found naturally in onions, apples, capers, and green tea.
How it works: Quercetin stabilizes mast cells and prevents them from “dumping” histamine. It also reduces Th2 cytokines, which are part of the allergy cascade (Mlcek et al., 2016).
How to use: Often taken as a capsule or powder, sometimes combined with vitamin C and bromelain to boost absorption. Common supplemental doses range from 250–1000 mg/day (divided), though food sources are always a good start.
Safety notes: Generally well tolerated; very high doses may interact with certain meds (e.g., antibiotics, blood thinners).
Vitamin C (Ascorbic Acid)
What it is: An essential antioxidant vitamin.
How it works: Vitamin C helps lower circulating histamine levels, likely by supporting histamine breakdown and clearance. Studies have shown that low vitamin C status is associated with higher histamine levels, while supplementation can reduce plasma histamine. (PMID: 17490952)
How to use: For daily support, many use 500–2000 mg/day (split doses). Can also be increased temporarily during allergy flares. Found in citrus, bell peppers, kiwi, and broccoli.
Safety notes: High doses may cause loose stools; buffered or liposomal forms are often gentler on digestion.
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Spirulina (Arthrospira platensis)
What it is: A nutrient-dense blue-green algae available as powders or tablets.
How it works: Spirulina modulates immune function, lowering interleukin-4 (IL-4) and IgE levels, and reducing histamine-driven symptoms.
Evidence:
RCT of 150 participants: spirulina improved nasal discharge, sneezing, congestion, and itching (Cingi et al., 2008).
RCT of 53 participants: spirulina (2 g/day) was more effective than cetirizine in reducing rhinorrhoea and nasal obstruction (Nourollahian et al., 2020, PMC7416373).
How to use: 1–2 g/day is common in studies. Best taken with food.
Safety notes: Ensure the brand is free of heavy metal contamination.
Butterbur (Petasites hybridus, Ze 339 extract)
What it is: A plant extract traditionally used for migraines and allergies.
How it works: Petasin and isopetasin act like natural leukotriene and histamine blockers.
Evidence:
RCT: Ze 339 was as effective as cetirizine for seasonal allergic rhinitis
Long-term safety confirmed in follow-up (Schäfer et al., 2004).
How to use: Most trials used 8–16 mg of standardized extract, 2–3x/day.
Safety notes: ONLY use PA-free butterbur extracts (pyrrolizidine alkaloids can damage the liver). See NCCIH safety note.
Intranasal Cromolyn (Nasalcrom)
What it is: An OTC nasal spray originally derived from a natural plant compound.
How it works: Cromolyn is a mast-cell stabilizer; it prevents histamine release before it happens. Works best when started before allergy season or allergen exposure.
How to use: 1 spray per nostril every 6–8 hours. Must be used consistently for full effect.
Safety notes: Very low systemic absorption → excellent safety profile. Approved for kids ≥2 years.
Stage 3: Late-Phase Inflammation
Hours later, other immune cells arrive and keep inflammation going.
This leads to congestion, fatigue, and lingering symptoms.
Conventional treatment: Nasal steroid sprays (Flonase, Nasonex). They suppress inflammation but can cause nosebleeds, tissue thinning, and hormone effects if used long-term (McDonnell et al., 2020).
Holistic support:
Nasal Saline Irrigation
What it is: A simple rinse (neti pot or spray bottle) with sterile saline.
How it works: Physically flushes allergens, histamine, and mucus from nasal passages. Improves symptoms, sleep, and quality of life.
How to use: Daily during allergy season, or after outdoor exposure. Always use distilled, boiled, or filtered water.
Safety notes: Safe for kids and adults when done properly.
Lifestyle & Environmental Support
HEPA air filters: Reduce indoor allergen load (dust, pollen, pet dander).
Magnesium: Helps stabilize mast cells and improve overall stress resilience.
Sunlight & grounding: Support circadian rhythm and immune balance.
Anti-Inflammatory Diet (Whole Foods, Omega-3s, Reduced Sugar)
What it is: A way of eating that emphasizes nutrient-dense, minimally processed foods while reducing dietary patterns that drive inflammation.
Why it matters for histamine/allergies: Chronic low-grade inflammation makes mast cells more reactive and increases histamine release. Diets high in refined sugar and processed seed oils can push the body toward a more pro-inflammatory state, while whole foods and healthy fats help calm that baseline.
How to apply it:
Whole foods: Build meals around fresh vegetables, fruits, pasture-raised meats, wild fish, legumes (if tolerated), and gluten-free grains.
Omega-3s: Cold-water fish (salmon, sardines, mackerel), chia seeds, flax seeds, and walnuts provide anti-inflammatory omega-3 fatty acids that balance out the omega-6 oils common in processed food. Clinical studies link higher omega-3 intake to reduced asthma and allergic disease severity (PMID: 28754005).
Reduce sugar & refined carbs: High sugar spikes insulin and inflammatory cytokines, which worsen allergy symptoms and make mast cells more “jumpy.” Cutting back on sodas, pastries, packaged snacks, and replacing them with fruit or whole-grain options can lessen the burden.
Safety notes: This isn’t a strict “diet,” but a framework for nourishing the immune system and calming inflammation. Works well for the whole family.
Probiotics to Support Immune Tolerance
What they are: Live bacteria (often found in fermented foods or supplements) that can beneficially shape the gut microbiome.
Why they matter for histamine/allergies: About 70% of the immune system lives in the gut. A balanced microbiome “teaches” the immune system to tolerate harmless exposures instead of overreacting with histamine. Dysbiosis (imbalanced gut bacteria) is linked to more allergies, asthma, and even eczema in children.
Evidence: Certain probiotic strains have shown reductions in allergic rhinitis symptoms and improvements in quality of life.
Certain Lactobacillus plantarum strains have been shown in vitro to degrade histamine, such as one strain isolated from miso that eliminated nearly all histamine in culture (PMID 28885051).
Meta-analyses show probiotics during pregnancy or early life can reduce the risk of atopic dermatitis in children (PMID 22441545).
Another analysis found probiotics given pre- and postnatally were protective against atopic dermatitis in both general and high-risk populations (PMID 24698503).
How to apply it:
Food sources: Fermented foods like sauerkraut, kefir, and yogurt (if tolerated). Note: some are high in histamine, so for histamine-sensitive people, choose carefully.
Supplements: Look for blends with low-histamine strains; start slow to avoid GI upset.
Timing: Daily use for several weeks to months is usually needed to see benefits.
Not all probiotics are equal. Some strains, like certain Lactobacillus casei and Lactobacillus bulgaricus, can actually produce histamine and may worsen symptoms in sensitive people. By contrast, Lactiplantibacillus plantarum, Lactobacillus rhamnosus GG, and Bifidobacterium infantis are considered low-histamine options and are usually better tolerated (PMC8308327; PMID 28885051)
Conventional Treatments: What you need to know
First-generation antihistamines (e.g., diphenhydramine/Benadryl, chlorpheniramine/Hycomine, hydroxyzine/Vistaril)
What to know:
They cross into the brain through the blood brain barrier leading to more sedation, slower reaction time, and impaired attention/memory; driving performance can be measurably worse after therapeutic doses. JACI Online
In young children, a large nationwide case-crossover study found a 22% higher seizure risk linked to recent first-gen antihistamine prescriptions (highest in ages 6–24 months). JAMA Network
In older adults, they add to anticholinergic burden (falls, delirium, cognitive decline) and are listed to avoid in the 2023 AGS Beers Criteria. PMID: 37139824
Practical takeaways:
Reserve for short, serious, targeted use (e.g., sudden hives, facial swelling).
Prefer newer, low-sedating or holistic options for daily use.
Second-generation antihistamines (e.g., cetirizine/Zyrtec, levocetirizine/Xyzal, loratadine/Claritin, fexofenadine/Allegra)
Why they are a better option than first-generation:
Similar allergy control with far less sedation for most people; generally better for school/work days, but does not come without problems.
But a nuance many miss — “withdrawal itch”:
The FDA (May 2025) added a warning that severe, sometimes “unbearable” itching can occur after stopping long-term cetirizine or levocetirizine, even in people who had no itch before. This is rare relative to how widely these meds are used, but real enough to warrant a label change and OTC warnings. U.S. Food and Drug Administration+2U.S. Food and Drug Administration
Earlier pharmacovigilance reports describe clusters of intense pruritus after discontinuation of (levo)cetirizine; some patients restarted the drug because the itch was so bad, suggesting a withdrawal phenomenon. SAGE Journals
I speak from personal experience, this is HORRIBLE! The withdrawal that I had from zyrtec was one of the worst things I have ever experienced. It truly was unbearable. I will never take a zrytec again.
Practical takeaways:
If you’ve taken cetirizine/levocetirizine daily for months/years, do not stop abruptly without a plan. Consider gradual tapering with your clinician (e.g., extend dosing intervals) and have a back-up itch plan.
My experience: I had to taper over months. I went from taking zrytec daily to every other day, then every 3 days. Then I started cutting the pills in half and took a half dose every other day then worked on spreading them out. I even got to taking a quarter pill every 3 days and was still having horrible withdrawal. This is not something to take lightly. My life revolved around this pill for months. Not everyone will experience this, but I will NEVER recommend that someone takes a second-generation histamine daily.
If you only use them as-needed (short bursts), this issue is far less likely.
Decongestants (pseudoephedrine, phenylephrine, oxymetazoline, etc.)
Decongestants don’t block histamine. Instead, they shrink swollen blood vessels in the nasal passages to temporarily relieve stuffiness. They can help you breathe more easily, but they don’t treat the underlying immune reaction.
Oral decongestants
Pseudoephedrine (Sudafed): Widely used and effective at reducing congestion, but comes with side effects like jitteriness, insomnia, rapid heartbeat, and increased blood pressure. Not recommended in children under 6 and used with caution in those with heart disease, high blood pressure, or anxiety.
Phenylephrine (Sudafed PE, Neo-Synephrine oral formulas): For years it was sold as a “safer” option, but in 2023 the FDA concluded oral phenylephrine is no better than placebo for congestion. It’s still on shelves but largely ineffective.
Topical nasal sprays
Oxymetazoline (Afrin, Vicks Sinex, Zicam): Works quickly by shrinking nasal blood vessels right where it’s applied. Helpful for severe short-term congestion (like before bed or a flight). If used longer than 3-4 days, there is significant chance of rebound congestion leading to reliance on the medication.
Phenylephrine nasal spray (Neo-Synephrine): Provides fast relief, but like oxymetazoline, the risk is rebound congestion if used longer than 3–4 days.
Safety notes
Children are more sensitive to side effects. Decongestants have been linked to irritability, rapid heartbeat, and in rare cases, seizures in young children. That’s why most guidelines advise avoiding OTC decongestants in children under 6 years.
Adults with high blood pressure, heart disease, thyroid disease, or insomnia often find symptoms worsen on decongestants.
Alternatives for congestion relief
Saline rinses or sprays: flush allergens and mucus without rebound effects.
Steam inhalation or humidifiers: moist air helps loosen mucus.
Essential oil rubs (like eucalyptus or peppermint): evidence is limited, but they may create a subjective sense of easier breathing.
Acupressure and gentle massage: can sometimes improve sinus drainage.
Decongestants can bring quick relief, but they are a short-term tool, not a long-term solution. They don’t address histamine release or immune balance, and in some cases can make congestion worse over time. For families trying to reduce reliance on conventional meds, saline rinses, air quality improvements, and anti-inflammatory support often provide safer, sustainable relief.
Histamine Intolerance & MCAS
Sometimes, allergy-like symptoms happen even without classic IgE allergy. That’s where histamine intolerance and mast cell activation syndrome (MCAS) come in.
Histamine Intolerance
Histamine intolerance isn’t a “true allergy.” It happens when the body’s histamine load is higher than its ability to break it down. The main enzyme for clearing histamine in the gut is diamine oxidase (DAO). When DAO is low (from genetics, gut damage, or nutrient deficiencies), histamine accumulates and causes allergy-like symptoms even without an allergen trigger.
Why DAO may be low
Gut inflammation (from IBS, IBD, celiac, or “leaky gut”) damages the cells that produce DAO.
Genetic polymorphisms in the DAO gene can reduce enzyme activity.
Medications such as NSAIDs, certain antibiotics, and antidepressants may inhibit DAO.
Nutrient deficiencies in vitamin C, vitamin B6, or copper can reduce DAO function.
Common symptoms
Headaches or migraines
Flushing or hives
Runny/stuffy nose
Bloating, diarrhea, abdominal cramps
Irregular menstrual cycles or heavy periods
Anxiety, palpitations, insomnia
**Symptoms often flare after meals, especially those rich in aged cheeses, processed meats, fermented foods, tomatoes, spinach, wine, or vinegar.
Support strategies
Low-histamine diet: Focus on fresh-cooked foods; avoid aged, canned, or fermented items.
Nutrient support: Vitamin C, B6, and copper support DAO activity.
DAO supplements: Enzyme capsules (porcine-derived or plant-based) may help some people process food histamine better.
Gut healing: Treating SIBO, IBD, or celiac can restore DAO-producing cells.
Probiotics: Certain strains (Bifidobacterium infantis, Lactiplantibacillus plantarum) are less likely to make histamine, while others (Lactobacillus casei, L. bulgaricus) can worsen it.
Mast Cell Activation Syndrome (MCAS)
MCAS is different from histamine intolerance, though the symptoms can overlap. It’s a disorder where mast cells (the immune cells that store histamine, prostaglandins, and other mediators) release their contents too easily and too often.
What triggers MCAS
Environmental allergens (pollen, mold, fragrances)
Infections (viral or bacterial)
Stress and hormonal changes
Heat, cold, or physical pressure
Certain foods, alcohol, or medications
Symptoms: Because mast cells release multiple mediators, not just histamine, symptoms can affect multiple systems:
Skin: flushing, hives, swelling
Respiratory: wheezing, throat tightness
Digestive: nausea, diarrhea, abdominal pain
Cardiovascular: rapid heart rate, low blood pressure, lightheadedness
Neurological: brain fog, fatigue, headaches
***Episodes can range from mild flushing to full-blown anaphylaxis-like reactions.
Diagnosis
MCAS is often underdiagnosed. Doctors may test for serum tryptase, urinary histamine metabolites, or prostaglandin D2 during or soon after a flare, but normal labs don’t rule it out. Diagnosis is often clinical, based on recurrent symptoms and response to mast-cell–targeting therapies.
Causes:
Mold exposure
Parasites
Dysbiosis
Poor diet
Leaky gut
heavy metals
Glyphosate/herbicides/pesticides
High toxin environment (cleaning products, makeup, etc)
Support and treatment (often takes up to 2 months to see improvement)
Conventional options:
H1 blockers (cetirizine, loratadine) for skin/respiratory symptoms
H2 blockers (famotidine) for GI involvement
Mast cell stabilizers (cromolyn sodium, ketotifen)
Leukotriene inhibitors (montelukast) in some cases
Holistic supports:
Quercetin and luteolin (bioflavonoids that stabilize mast cells)
Low-histamine diet and anti-inflammatory eating
Stress management and adequate sleep (since cortisol influences mast cells)
Vitamin D and magnesium, both important for immune balance
Emergency plan: Anyone with MCAS who’s had severe reactions should carry epinephrine.
Key differences: Histamine Intolerance vs MCAS
Histamine intolerance is more about excess histamine load & low DAO breakdown.
MCAS is more about mast cells being unstable and releasing histamine + other mediators too often.
Both may improve with low-histamine diets and bioflavonoids, but MCAS often needs medication support.
Specific Product Recommendations:
Earthley Sinus Saver: Natalie10off for 10% off
Great for taking every day to support your sinuses and to help support your body's natural response to allergens. In my experience taking this, it takes a few doses to be effective. By about the 4th dose, my sinuses will completely drain within 15 mins of taking it. It's super effective!
Homeopathy, multi-symptom relief for indoor and outdoor allergies in children
Homeopathic multi symptom relief
Homeopathic medicine that relieves allergy symptoms, take at the first sign of symptoms
Propolis, Quercetin, Bromelain, Nettle Leaf
Histamine Support with Bioflavonoids, Natural Nettle, Quercetin, Rutin, Bromelain, for Immune System and Inflammation Support, Seasonal Support
This invigorating nasal spray is formulated with expectorant ingredients that combats congestion while also reducing inflammation and fighting against bacterial and viral invaders.
peppermint and lavender
Emergencies: The Anaphylaxis Disclaimer
Not every allergic reaction is mild. Anaphylaxis is life-threatening.
Warning signs: throat tightness, swelling of lips/tongue, difficulty breathing, dizziness, vomiting, drop in blood pressure.
What to do:
Epinephrine is the first-line treatment. Antihistamines only help with skin symptoms; they do NOT stop airway closure or shock.
Call 911 immediately after epinephrine or if experiencing any symptoms of anaphylaxis.
Natural supports are for prevention and everyday symptom relief, not emergencies.
Conclusion
Histamine is essential. It’s part of how the body fights infections and heals. But when the system misfires, it can lead to allergies, histamine intolerance, or MCAS.
Conventional meds bring quick relief but don’t fix root causes and may carry risks.
Holistic tools from quercetin and vitamin C to spirulina, saline rinses, and low-histamine diets offer safe and effective ways to bring balance.
Emergency care matters. Always use epinephrine for anaphylaxis.
With the right blend of knowledge, preparation, and natural support, families can navigate allergy season and chronic histamine issues more confidently.
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