What’s the Link Between Long COVID and Histamine Intolerance?
If you’re months into Long COVID and still experiencing symptoms like rashes, anxiety, food reactions, or heart palpitations, you might be wondering: could this be histamine intolerance?
There is growing evidence that some Long COVID symptoms may be related to how your body processes histamine. While the two conditions are not the same, they may overlap in ways that matter for your recovery. Understanding the link could provide answers, and potential relief.
Can Long COVID Trigger Histamine Intolerance?
Long COVID refers to symptoms that persist or appear after the acute phase of COVID-19, lasting weeks, months, or even longer. Common features include fatigue, brain fog, chest pain, gastrointestinal issues, and dizziness. Many people also develop food and chemical sensitivities, skin reactions, and autonomic dysfunction.
Histamine intolerance happens when the body cannot break down histamine efficiently. This can result in a wide range of symptoms that mimic allergies or inflammatory conditions. In some cases, the issue may involve the enzyme diamine oxidase (DAO), which helps break down histamine in the gut. If DAO activity is low, or if histamine production is high due to immune activation, symptoms can arise.
For some people with Long COVID, antihistamines seem to reduce symptoms. That has led researchers to explore the possibility that COVID-related inflammation may trigger histamine sensitivity or contribute to mast cell dysfunction.
Key Symptoms of Histamine Intolerance
The symptoms of histamine intolerance can overlap significantly with those of Long COVID. These may include:
Itchy skin, hives, or flushing
Headaches or migraines
Bloating, cramping, and other digestive issues
Dizziness or a racing heart
Heat intolerance or sweating
Food sensitivities or reactions to wine, chocolate, and fermented foods
Anxiety or panic-like episodes
These symptoms occur when histamine builds up faster than your body can clear it. This buildup may be worsened by stress, illness, or injury—all of which are common during post-COVID recovery.
Where Long COVID and Histamine Intolerance Intersect
Emerging research highlights several ways in which Long COVID and histamine-related symptoms may overlap:
1. Immune Dysregulation and Mast Cell Activation
Mast cells are immune cells that store and release histamine. COVID-19 may lead to persistent mast cell activation, which contributes to symptoms like fatigue, hives, dizziness, and brain fog. This mast cell overactivity is also seen in a condition known as mast cell activation syndrome (MCAS), which shares many features with both Long COVID and histamine intolerance.
2. DAO Enzyme Disruption
SARS-CoV-2 has been shown to affect gut function and the intestinal barrier. This disruption can impair DAO production in the gut, which makes it harder to clear histamine from food or the environment. If histamine clearance slows down, symptoms can escalate even with normal dietary intake.
3. Autonomic Nervous System Dysfunction
Long COVID can involve dysautonomia, including postural orthostatic tachycardia syndrome (POTS). Histamine can worsen these symptoms by increasing heart rate, causing lightheadedness, and triggering flushing or blood pressure changes. These patterns can easily be mistaken for anxiety or panic attacks.
4. Symptom Improvement with Antihistamines
Some studies have reported symptom improvement in Long COVID patients treated with antihistamines. Both H1 blockers (like loratadine) and H2 blockers (like famotidine) have shown promise in reducing symptoms for certain individuals. This suggests that histamine may be playing a role in at least a subset of cases.
Up to 80% of your body’s histamine is stored in mast cells, and when those cells stay activated after an infection, symptoms like fatigue, anxiety, and food reactions can persist long after you recover.
Why Might Histamine Intolerance Develop After COVID?
Post-viral syndromes can create ongoing immune activation. In the case of Long COVID, there are several possible mechanisms behind new or worsened histamine sensitivity:
Mast cells may remain in a “primed” state, releasing histamine more easily.
Ongoing inflammation may make blood vessels more permeable, worsening symptoms like brain fog and fatigue.
Persistent immune activity can disrupt normal histamine regulation.
Autonomic nervous system dysfunction can amplify responses to histamine.
In other words, your body may still be reacting to the original infection, and histamine may be one of the ways it signals distress.
When to Suspect Histamine Involvement in Long COVID
You may want to consider histamine as a contributing factor if you notice:
Symptoms worsen after eating leftovers, wine, fermented foods, or aged cheeses
You experience flushing, rashes, or itchiness without a known allergy
Food reactions are new or have become more frequent
Symptoms spike with stress, heat, exercise, or exertion
Antihistamines reduce your symptoms noticeably
While these clues do not confirm histamine intolerance, they may suggest that histamine is playing a role in your recovery.
How to Support Recovery if Histamine Is Involved
If histamine overload seems to be part of your Long COVID experience, here are some gentle strategies to consider:
1. Food and Diet
Try a low-histamine diet for two to four weeks. This is not a long-term restriction, but a way to reduce the histamine load while your body resets.
Avoid common high-histamine foods like wine, aged cheeses, vinegars, smoked meats, and fermented products.
Eat fresh-cooked meals and avoid leftovers or slow-cooked dishes.
2. Nervous System Regulation
Stress increases mast cell activation. Daily breathwork, EFT, meditation, or gentle movement like stretching can help calm your immune and nervous systems.
3. Supplement Support
DAO enzyme supplements may help some people who have gut-based histamine intolerance.
Vitamin C and quercetin can help stabilize mast cells.
Magnesium glycinate may support both relaxation and histamine breakdown.
4. Medications (With Medical Guidance)
Some practitioners use H1 and H2 antihistamines to reduce symptoms in select patients. These include over-the-counter medications like loratadine and famotidine. Always consult your healthcare provider before starting any new treatment.
If your Long COVID symptoms feel unpredictable, food-triggered, or flare without warning, histamine may be involved. This doesn’t mean you’ll be stuck with it forever. But it might give you a helpful direction to explore.
You’re not imagining your symptoms. You’re responding to a complex condition, and for some people, histamine is part of that picture.
If you’re looking for a place to start, consider trying a short-term low-histamine approach with us at Bloomin’ Well. Schedule your free, 15-minute discovery call to see how we can help.
Healing takes time, but there are tools that can help you move forward with more clarity and less overwhelm.
