Histamine Intolerance: What It Means for Your Health (and How It Can Affect MS Symptoms)

Most of us have heard of antihistamines—those little pills that promise relief from itchy eyes, runny noses, and allergic flare-ups. But while we often associate histamines with seasonal allergies, they play a far more complex role in the body than many people realise.

For people living with multiple sclerosis (MS), understanding histamines—and how your body processes them—can be an important part of supporting your immune system, gut health, and overall wellbeing.

What Exactly Are Histamines?

Histamines are chemical messengers that:

• Help regulate immune activity

• Play a role in digestion by stimulating stomach acid

• Influence sleep-wake cycles

• Act as neurotransmitters in the brain

In healthy amounts, they’re essential. Problems arise when histamines build up—either because your body is producing too much or because you’re not breaking them down effectively.

Histamine Intolerance: When Your Body Can’t Keep Up

Some people naturally have lower levels of the enzymes that break down histamine—particularly diamine oxidase (DAO) and histamine-N-methyltransferase (HNMT).

These enzymes can be affected by:

• Genetics

• Certain medications

• Alcohol

• Nutrient deficiencies

• Hormonal changes throughout the menstrual cycle

  
  

Your gut health also matters. Research shows that people with histamine intolerance often have a less diverse gut microbiome, higher markers of inflammation, and signs of increased intestinal permeability (“leaky gut”).

Symptoms Can Mimic Allergies

Histamine intolerance doesn’t look the same for everyone, but common symptoms include:

• Flushing, headaches, or migraines

• Runny nose or nasal congestion

• Skin rashes or hives

• Swelling

• Nausea, dizziness, or fatigue

• Digestive issues (bloating, diarrhoea, constipation)

  
  

These symptoms are often mistaken for allergies or other sensitivities, which is why histamine intolerance is frequently overlooked.

Food Sources of Histamine

Histamines aren’t just made by your body—they’re also found in certain foods, especially those that are aged, cured, or fermented. Examples include:

• Cheese (aged varieties in particular)

• Cured, canned, or fermented meats and fish

• Fermented vegetables like sauerkraut or kimchi

• Certain fruits and vegetables such as spinach, tomatoes, strawberries, and citrus

• Alcohol, especially wine and beer

  
  

Freshness matters—histamine levels rise in food the longer it’s stored, especially in protein-rich foods like fish and meat.

Interventions for Histamine Intolerance

If you suspect histamine intolerance, your practitioner may recommend:

• Testing for DAO enzyme activity or related genetic variations

• A short-term low-histamine diet to identify trigger foods. A low-histamine diet typically removes high-histamine foods for 10 days to several weeks, followed by a careful reintroduction to identify personal triggers. Keeping a food and symptom diary can make this process much easier.

• DAO enzyme supplements in some cases

• Nutrient support (vitamin C, B6, copper) to help your body break down histamine

  
  

Foods That Support Histamine Breakdown and Immune Balance

Some fresh, nutrient-rich foods can help reduce histamine’s impact by supporting the enzymes that break it down, calming mast cell activation, and lowering inflammation.

Vitamin C-rich foods — help degrade histamine and support DAO enzyme function:

• Bell peppers, broccoli, kiwi, parsley, papaya, blueberries

Vitamin B6 foods — important for DAO production:

• Chicken, turkey, sunflower seeds, pistachios, bananas, sweet potatoes

Copper-rich foods — a cofactor for DAO activity:

• Cashews, sesame seeds, sunflower seeds, shiitake mushrooms

Anti-inflammatory fresh herbs — may help calm histamine-related inflammation:

• Parsley, basil, coriander, dill

Low-histamine fruits & vegetables — reduce histamine load while providing fibre and antioxidants:

• Apples, pears, watermelon, mango, leafy greens, root vegetables

  
  

Nettle: Nature’s Seasonal Ally

One plant worth special mention is stinging nettle (Urtica dioica). Traditionally used for seasonal allergy relief, nettle contains compounds like quercetin and kaempferol that:

• Stabilise mast cells (reducing histamine release)

• Provide anti-inflammatory effects

• Supply vitamin C, magnesium, and iron — all helpful for histamine metabolism

Nettle tea is one of the easiest ways to enjoy its benefits — and here’s something fascinating: nettles naturally grow and are ready to harvest in spring, the very time of year when pollen counts and seasonal allergies are at their highest. Nature seems to know when we need it most.

Why This Matters for MS

Histamine is deeply linked with inflammation, immune activation, and gut health—three areas that also influence MS symptoms and flares. While histamine intolerance isn’t a root cause of MS, for some people it can be another layer of immune and inflammatory stress. Reducing histamine load may help ease certain symptoms like headaches, fatigue, or digestive discomfort, supporting a calmer immune environment.

Practical Tips to Reduce Histamine Load

• Choose fresh over processed—buy from local farmers’ markets when possible

• Opt for fresh meat or fish instead of cured, smoked, or leftover options

• If you eat dairy (not recommended with MS), swap aged cheeses for fresh options like mozzarella, ricotta, or goat cheese

• Store food carefully and eat leftovers quickly to limit histamine build-up

• Consider making your own fresh juices or smoothies instead of shop-bought versions

  
  

Bottom line: If you’re living with MS and experiencing allergy-like or digestive symptoms that don’t seem to have an obvious cause, histamine intolerance could be worth exploring. Working with a practitioner can help you identify whether histamines are adding to your symptom burden—and guide you towards a diet that helps you feel your best.