onion
Vegetables
Is onion high in histamine?
Find out whether onion is high or low in histamine, see its exact rating, and check its FODMAP, salicylate, oxalate and diet compatibility all in one place.
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Compare onion across criteria
Sensitivity notes
Why histamine food checker matters
Histamine is a compound naturally present in many foods, especially aged, fermented, or preserved items. In sensitive individuals, excess histamine can cause headaches, flushing, hives, digestive issues, and other symptoms. Your body normally breaks down histamine, but some people have reduced capacity to do so.
- Focus on fresh foods - histamine builds up as food ages
- Cook and eat meals fresh; avoid leftovers sitting more than 24 hours
- Be cautious with fermented foods, aged cheeses, and cured meats
Triggers
Diets
Serving size, prep, and portion notes for onion
Onion is graded E for fructans and E for total FODMAPs, the top of our scale, which is why it is the single most common trigger people uncover once they start logging food against symptoms. The reaction is a carbohydrate problem rather than an allergy: onion is A for histamine, A for oxalates, A for lectins and A for nightshades, so if onion bloats you the fructans are almost certainly the mechanism. It also grades E for low fermentation SIBO plans. The frustrating part is that fructans are water soluble and heat stable, so caramelizing, slow simmering or fishing the pieces out of a sauce does not make onion any safer, and onion hidden in stock, gravy and spice blends is why so many people react to restaurant food they cannot account for.
Watch for
Fructans and total FODMAPs both graded E, the highest tier we use, and the grade does not soften between raw and cooked onion / Cooking is not a fix: fructans dissolve out of the onion into the pan and stay in the liquid, so straining the pieces out leaves the trigger in the sauce / Hidden onion drives most unexplained flare-ups: stock cubes, gravies, curry pastes, spice rubs, chips and anything listed as seasoning or natural flavor / Graded E for low fermentation SIBO, so onion is usually one of the first things pulled when working through a SIBO protocol / Clean on the rest of the chemistry (histamine A, oxalate A, lectin A, nightshade A, with only a borderline B for histamine liberation), which is why an onion reaction is nearly always intolerance rather than allergy
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Histamine Guide
Everything you need to know about histamine sensitivity and smart food choices.
Histamine is a compound naturally present in many foods, especially aged, fermented, or preserved items. In sensitive individuals, excess histamine can cause headaches, flushing, hives, digestive issues, and other symptoms. Your body normally breaks down histamine, but some people have reduced capacity to do so.
Sensitivity varies widely. What triggers one person may be fine for another. Track your reactions to find your personal threshold.
These foods are generally well-tolerated for Histamine sensitivity:
View all safe options
These foods have moderate levels and may be tolerated in small amounts:
These foods are high in histamine and may trigger symptoms:
View full list
If you're sensitive to Histamine, consider these strategies:
- 1Focus on fresh foods - histamine builds up as food ages
- 2Cook and eat meals fresh; avoid leftovers sitting more than 24 hours
- 3Be cautious with fermented foods, aged cheeses, and cured meats
- 4Consider that stress and hormones can affect your histamine tolerance
- 5Some antihistamines or DAO supplements may help (consult your doctor)
Pro tip: Keep a food diary to track your reactions. The Triggerbites app makes this easy with automatic pattern detection.
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Get the AppFAQ
Is onion high in Histamine?
Histamine: low signal for most people.
Can I still eat onion if I'm sensitive to Histamine?
Usually fine in normal portions.
What else should I check?
Check FODMAPs, Fructans, and Low Fermentation next for a fuller picture.