Rosemary is considered low histamine and safe for a low-histamine diet. On the Swiss Interest Group Histamine Intolerance (SIGHI) food compatibility list, one of the most widely referenced guides for histamine intolerance, rosemary scores a 0, meaning it’s well tolerated and carries no known histamine risk. Beyond being safe, rosemary contains compounds that may actively work against histamine in the body.
Rosemary’s SIGHI Score and Diet Lists
The SIGHI food list rates foods on a scale from 0 (well tolerated) to 3 (very poorly tolerated). Rosemary earns the best possible score of 0. It doesn’t contain significant histamine, it isn’t known to trigger histamine release from immune cells, and it doesn’t block the enzymes your body uses to break histamine down. Other widely circulated histamine food lists confirm this. Rosemary appears in the “generally safe” category for herbs and spices on multiple clinician-compiled guides.
This applies to rosemary in its common culinary forms: fresh sprigs, dried leaves, and ground rosemary. Unlike certain spices such as cinnamon, clove, or chili powder, which appear on some restricted lists for their potential to trigger histamine release, rosemary carries no such warnings.
How Rosmarinic Acid Affects Histamine
Rosemary’s most studied active compound, rosmarinic acid, doesn’t just passively avoid histamine. It appears to reduce histamine release at a cellular level. In laboratory research, rosmarinic acid inhibited mast cell activation, the process where immune cells dump histamine into surrounding tissue. It did this by blocking a specific signaling pathway that mast cells use to degranulate, and it also disrupted the calcium signaling that drives the release process. The result was significantly lower histamine secretion from treated cells.
Rosmarinic acid also suppresses the production of inflammatory immune signals like certain interleukins and reduces levels of eosinophils and neutrophils, two types of white blood cells heavily involved in allergic reactions. In animal studies, mice pretreated with rosmarinic acid-rich plant extracts showed a blunted inflammatory response compared to untreated mice, with proportionally lower levels of immune cells and inflammatory markers.
What Human Studies Show
Human trials on rosmarinic acid for allergies have produced mixed results. In studies of people with seasonal allergic rhinitis (hay fever), those who received rosmarinic acid-enriched plant extracts had decreased neutrophil and eosinophil counts in nasal lavage samples compared to placebo groups, suggesting reduced nasal inflammation at the cellular level.
However, not all results have been positive. A double-blind, placebo-controlled crossover trial tested mint tea high in rosmarinic acid (one cup twice daily for four weeks) in 22 adults with nasal polyposis. The tea did not improve nasal stuffiness, airflow, sleep quality, or sense of smell compared to placebo. There was no statistically significant difference in any symptom measure. This suggests that while rosmarinic acid shows real anti-inflammatory activity in lab and animal models, drinking rosemary or mint tea in normal amounts may not deliver enough of the compound to meaningfully reduce allergy symptoms.
The takeaway for people with histamine intolerance: rosemary is safe to eat and contains compounds that work against histamine at a biological level, but cooking with it won’t function as a treatment for your symptoms.
Rosemary Essential Oil and Skin Reactions
While eating rosemary is well tolerated, topical rosemary products deserve a note of caution. Allergic contact dermatitis from rosemary extract has been documented, though it’s considered rare. In one published case, a woman developed itchy redness on her face from a cleansing gel containing rosemary leaf extract. Patch testing confirmed the rosemary extract as the cause. The compound carnosol, a naturally occurring diterpene in rosemary, has been identified as a likely trigger for these skin reactions.
Both rosemary extracts in cosmetics and raw rosemary material have caused contact dermatitis in case reports, and extremely rare cases of anaphylaxis exist in the medical literature. This is a contact allergy issue rather than a histamine content issue. If you have mast cell activation syndrome or very reactive skin, patch-testing a new rosemary-containing skincare product before applying it to your face is a reasonable precaution. Cooking with rosemary does not carry this same risk.
Using Rosemary on a Low-Histamine Diet
Rosemary is one of the more versatile herbs available to people following a restricted low-histamine diet, especially since several other common seasonings can be problematic. You can use it freely in fresh, dried, or ground form to add flavor to meats, roasted vegetables, soups, and baked goods. It pairs well with other low-histamine herbs like basil, oregano, and thyme, all of which also belong to the same plant family (Lamiaceae) and share rosmarinic acid as a common compound.
One practical tip: because a low-histamine diet often restricts fermented seasonings, aged sauces, and vinegar-based dressings, fresh herbs like rosemary become especially valuable for making meals taste satisfying. Rosemary-infused olive oil, for example, can substitute for more complex dressings that might contain problematic ingredients.