Is watermelon high in histamine?
Watermelon is probably low in histamine, but no study we use has measured it. We rate it 0 as an estimate: it is a fresh, unfermented fruit, and its measured plant relatives had little or no histamine.
- Histamine
- Not measured
- Other amines
- Not measured
- Liberator
- Not on the lists we use
- DAO blocker
- No evidence
What each source says
| Source | Verdict | What it says, in our words |
|---|---|---|
| Related plants measured in Spain, 2018 review 1 | Cucumber (10 samples) and courgette (41) had no detectable histamine; pumpkin had traces in a few of 12 samples. | |
| 10 published low-histamine diets (2021 review) 2 | Watermelon is not on the review's chart of excluded foods. | |
| SIGHI food list 3 | See source | See SIGHI's own list for its rating. |
How freshness and processing change it
A whole watermelon keeps for a while, but once cut it is a wet, sugary surface for bacteria. Pre-cut watermelon sold chilled in tubs has an unknown history between cutting and eating. None of this has been measured for histamine; cut a whole one yourself, keep the pieces covered in the fridge and eat them within a day or two.
Not measured; fresh and unfermented. (estimate)
Not measured. Cut fruit stored for an unknown time gives bacteria longer to act. (estimate)
Why we rate watermelon 0
Watermelon is a common summer question on low-histamine forums, and the honest answer is that no study we use has measured it. It does not appear in the 2018 review's tables, which cover 19 fruits from the Spanish market plus data from other studies, or in the 2021 table of foods sold in Spain. So we label it "not measured", and the rating on this page is our estimate.
The estimate starts from how histamine gets into food. It forms mainly when bacteria break down histidine, an amino acid found in protein, so the foods that build it up are fish and meat kept too long and fermented products such as aged cheese, cured sausage and wine. A fresh watermelon is none of these. It is mostly water and sugar, with very little protein, and nothing in how it is grown or sold involves fermentation.
The nearest relatives that have been measured point the same way. Watermelon belongs to the same plant family as cucumber, courgette and pumpkin. Ten cucumbers and 41 courgettes sold in Spain had no detectable histamine, and pumpkin had traces in only a few of 12 samples, never above 1.90 mg/kg. That is family resemblance, not a measurement of watermelon, but it is consistent. Fruit in general is low too: a 2020 review pooled 136 fruit samples from the Spanish market and found an average of 0.07 mg/kg of histamine.
The lists agree. Watermelon is not on the 2021 review's chart of foods excluded by ten published low-histamine diets, and none of our sources names it as a suspected "histamine liberator".
We rate fresh watermelon 0, "low", as an estimate. The form we would treat with more care is pre-cut watermelon sold in tubs, because cut fruit kept for an unknown time gives bacteria longer to act; we rate it 1, also an estimate. Buying a whole or half watermelon, cutting it yourself and keeping the pieces covered in the fridge is the simple way around that.
Questions about watermelon and histamine
Is watermelon low histamine?
Probably, though no study we use has measured it. It is a fresh, unfermented fruit with little protein, its measured plant relatives had little or no histamine, and it is not on the 2021 chart of foods excluded by ten published diets.
Is pre-cut watermelon OK on a low-histamine diet?
It was not measured. Cut fruit kept for an unknown time gives bacteria longer to act, so we rate pre-cut watermelon 1 as an estimate and suggest cutting a whole one yourself.
Evidence behind this page
- No study in our sources reports histamine in watermelon, and it is not on the 2021 review's chart of foods excluded by ten published low-histamine diets. 2
- Histamine in food forms mainly when bacteria decarboxylate histidine; the foods most at risk are those spoiled by bacteria and fermented products. 24
- Cucumbers (10 samples) and courgettes (41 samples) sold in Spain had no detectable histamine; pumpkin had a trace in a few of 12 samples, up to 1.90 mg/kg. 1
- Across 136 fruit samples from the Spanish market, histamine averaged 0.07 mg/kg, and the highest single sample had 2.51 mg/kg. 4
Sources
- Sánchez-Pérez S, Comas-Basté O, Rabell-González J, Veciana-Nogués MT, Latorre-Moratalla ML, Vidal-Carou MC. Biogenic Amines in Plant-Origin Foods: Are They Frequently Underestimated in Low-Histamine Diets? Foods 7(12):205, 2018. doi:10.3390/foods7120205 (Sánchez-Pérez S et al. 2018)
- Sánchez-Pérez S, Comas-Basté O, Veciana-Nogués MT, Latorre-Moratalla ML, Vidal-Carou MC. Low-Histamine Diets: Is the Exclusion of Foods Justified by Their Histamine Content? Nutrients 13(5):1395, 2021. doi:10.3390/nu13051395 (Sánchez-Pérez S et al. 2021)
- Swiss Interest Group Histamine Intolerance (SIGHI). Food compatibility list for histamine intolerance. histaminintoleranz.ch (accessed November 2026), 2026. Link (Swiss Interest Group Histamine Intolerance (SIGHI) 2026)
- Comas-Basté O, Sánchez-Pérez S, Veciana-Nogués MT, Latorre-Moratalla M, Vidal-Carou MDC. Histamine Intolerance: The Current State of the Art. Biomolecules 10(8):1181, 2020. doi:10.3390/biom10081181 (Comas-Basté O et al. 2020)