Dai Dai Hua
StarCitrus aurantium L. var. amara Engl.
Traditionally used for
- Digestion
- Sleep
- Mood & calm
Cautions & contraindications
- Heart conditions
☯ TCM Properties
Regulates Qi and Widens the Chest; Harmonizes the Stomach and Stops Vomiting; Strengthens the Spleen and Opens the Appetite; Soothes the Liver and Regulates Qi
Traditional Chinese Uses
Dai Dai Hua (bitter orange flower, Seville orange flower) is a warm, aromatic herb used in Chinese medicine to move Liver Qi, harmonize the Stomach, and calm the Shen. Its Qi-moving action addresses the chest tightness, epigastric fullness, and emotional irritability of Liver Qi stagnation. It also settles nausea, vomiting, and belching from rebellious Stomach Qi. Its mild Shen-calming quality benefits anxiety and mild insomnia related to Liver Qi stagnation causing restlessness.
Western Herbalism Properties
Relationships
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Botanical Description
Citrus aurantium var. amara, the bitter or Seville orange, is a small to medium-sized evergreen tree in the Rutaceae, 4 to 10 meters tall with a dense, rounded crown and stiff, often sharply spiny branches. The bark is grey-brown and the alternate leaves are leathery, broadly ovate to elliptic, 7 to 10 cm long, with a faintly crenulate margin and a characteristically broadly winged petiole. The leaves and other tissues are dotted with translucent oil glands that release a strong citrus aroma when crushed. Flowers are borne singly or in small axillary clusters, white, very fragrant, 2 to 3 cm across, with five thick fleshy petals and numerous yellow stamens; these are the source of orange-flower water and neroli oil. The fruit is a hesperidium 7 to 8 cm in diameter, with a rough, deep orange rind rich in essential oil and a markedly bitter, sour pulp. The dried flower bud and flower constitute the drug Dai Dai Hua.
Active Constituents
p-Synephrine
Phenylethylamine protoalkaloidConcentration: the dominant alkaloid of the dried blossom, making up 50.56% of the total alkaloid fraction (Shen et al., 2017); the absolute content of the flower is lower than that of the immature fruit drugs Zhi Shi and Zhi Ke
A sympathomimetic amine structurally close to phenylephrine, acting mainly at beta-3 and, more weakly, alpha-1 adrenoceptors. It is the constituent behind every cardiovascular signal attributed to bitter orange: a meta-analysis of 18 placebo-controlled human trials found prolonged use raised systolic pressure by 6.37 mmHg and diastolic by 4.33 mmHg. It is also why bitter orange became the standard ingredient of ephedra-free weight-loss products.
Neohesperidin
Flavanone-7-O-neohesperidosideConcentration: with hesperidin and naringin, 83.94% of the total flavonoid fraction of the dried blossom (Shen et al., 2017)
One of the bitter neohesperidoside flavanones that give the drug its taste. In mice and in human volunteers, neohesperidin together with synephrine trapped the reactive dicarbonyls glyoxal and methylglyoxal, forming adducts recoverable in urine.
Naringin
Flavanone-7-O-neohesperidosideConcentration: part of the hesperidin/naringin/neohesperidin group that accounts for 83.94% of total flavonoids in the blossom
Antioxidant flavanone glycoside. Naringin and its aglycone naringenin inhibit CYP3A4 and OATP transporters in vitro, and are commonly invoked in citrus drug-interaction discussions, although in grapefruit the clinically dominant inhibitors proved to be the furanocoumarins rather than naringin.
Hesperidin
Flavanone-7-O-rutinosideConcentration: part of the hesperidin/naringin/neohesperidin group that accounts for 83.94% of total flavonoids in the blossom
A vasoprotective flavanone glycoside with antioxidant activity; the flavonoid fraction of the blossom showed the strongest DPPH radical scavenging, ferric-reducing power and reducing power of the five fractions tested.
Linalool
Acyclic monoterpene alcoholConcentration: the principal component of neroli, the flower essential oil, reported at roughly 25-29% depending on origin
The main odorant of neroli and the compound usually credited with its sedative and anxiolytic effect in inhalation studies. Linalool is a recognised contact allergen once oxidised, which matters for topical rather than internal use.
Limonene
Monocyclic monoterpene hydrocarbonConcentration: reported up to about 41% of the flower oil in some samples, and about 12% in others; highly variable between origins
A volatile terpene contributing to the citrus odour of the drug. Limonene is a mild CYP inducer in rodents at high dose and a skin irritant when oxidised, but has no established interaction at culinary or decoction exposures.
Coumarins
BenzopyroneConcentration: a coumarin fraction was isolated from the dried blossom by Shen et al. (2017), but the individual coumarins were not identified and no furanocoumarin has been quantified in the flower
This matters because the furanocoumarins that drive the well-documented CYP3A4 interaction of this variety — 6',7'-dihydroxybergamottin, bergamottin and bergapten — have been characterised in the fruit and juice, not in the flower. Do not assume the flower is free of them, and do not assume it carries them at fruit-juice levels; neither has been shown.
⚠ Drug Interactions
Monoamine oxidase inhibitors (phenelzine, tranylcypromine, moclobemide, selegiline, linezolid)
p-Synephrine, octopamine and tyramine, all present in this variety, are indirect and direct sympathomimetic amines and substrates for monoamine oxidase. When MAO is inhibited, dietary and herbal sympathomimetic amines accumulate and can precipitate an acute hypertensive episode. The mechanism is the classic tyramine-MAOI interaction; no case series specific to bitter orange flower exists, which is why this is graded Possible rather than Established.
Clinical note: Do not prescribe Dai Dai Hua to a patient on any MAO inhibitor, including linezolid, and allow a two-week washout after stopping an irreversible MAOI.
Caffeine and other stimulants (ephedrine, pseudoephedrine, stimulant weight-loss supplements)
A meta-analysis of 18 placebo-controlled trials found that prolonged p-synephrine use significantly raised both systolic (6.37 mmHg) and diastolic (4.33 mmHg) blood pressure while producing no significant weight loss. European risk assessments specifically flag high synephrine intake combined with caffeine and exercise as the high-risk pattern. There is a second, distinct hazard here: bitter orange is one of the commonest ingredients of ephedra-free slimming products, and analyses have found the non-natural isomer m-synephrine (phenylephrine) in some of those products as an adulterant. m-Synephrine is a considerably stronger alpha-adrenoceptor agonist than the p-isomer that occurs in the plant.
Clinical note: Ask specifically about weight-loss, pre-workout and thermogenic supplements before prescribing this herb, and avoid the combination in anyone with hypertension, arrhythmia, coronary disease or hyperthyroidism. A commercial bitter orange extract is not interchangeable with a decoction of the dried flower.
CYP3A4 substrates (felodipine, ciclosporin, indinavir, simvastatin, midazolam)
In a randomised three-way crossover in 10 volunteers, 240 mL of Seville orange juice raised the felodipine area under the curve by 76%, comparable to dilute grapefruit juice at 93%, through inactivation of intestinal CYP3A4; 6',7'-dihydroxybergamottin inhibited CYP3A4 activity in intestinal epithelial cells by 93% (Malhotra et al., 2001). That study used the juice of the fruit of this variety, not the flower. A coumarin fraction has been isolated from the dried blossom but its furanocoumarin composition has not been characterised, so the extent to which the flower shares this interaction is unknown.
Clinical note: Treat as a real possibility rather than a certainty. With a narrow-therapeutic-index CYP3A4 substrate such as ciclosporin or tacrolimus, monitor levels if the patient starts or stops a Dai Dai Hua formula, and warn them separately not to take the fruit juice.
Antihypertensives and beta-blockers
The same meta-analysis showing a 6.37/4.33 mmHg pressure rise with prolonged p-synephrine implies pharmacodynamic opposition to antihypertensive therapy. Bitter orange preparations are also reported to raise heart rate, which works against the intended effect of rate-controlling agents.
Clinical note: Check blood pressure a fortnight after starting the herb in any treated hypertensive, and stop it if control deteriorates.
Evidence Tier
Strong evidence · 6 studiesRecorded studies by study design, strongest design at the top. This is a study-design tier only, not a GRADE rating: it does not weigh risk of bias, consistency or precision.
Systematic review / meta-analysis
1
1 verified · 0 unverified
Randomized controlled trial
3
3 verified · 0 unverified
Other clinical trial
0
Observational / case report
0
In vitro / animal
2
0 verified · 2 unverified
Other / unclassified
0
Verified: design read from PubMed for a DOI that resolves to the cited paper Unverified: taken from the study's recorded description
Clinical Studies
The Safety and Efficacy of Citrus aurantium (Bitter Orange) Extracts and p-Synephrine: A Systematic Review and Meta-Analysis
Meta-analysis of 18 placebo-controlled human trials of p-synephrine and bitter orange extract. Prolonged use significantly raised systolic blood pressure by 6.37 mmHg (95% CI 1.02-11.72) and diastolic by 4.33 mmHg (95% CI 0.48-8.18), while weight loss was non-significant and body composition unchanged. The authors conclude that synephrine tends to raise blood pressure and heart rate with no evidence of a weight-loss benefit.
Seville orange juice-felodipine interaction: Comparison with dilute grapefruit juice and involvement of furocoumarins
Randomised three-way crossover in 10 volunteers. Felodipine AUC rose 76% with 240 mL Seville orange juice and 93% with dilute grapefruit juice relative to common orange juice, indicating a shared mechanism of intestinal CYP3A4 inactivation. 6',7'-Dihydroxybergamottin at 10 micromolar inhibited CYP3A4 in cultured intestinal epithelial cells by 93%, bergapten by only 34%. The material tested was the fruit juice of Citrus aurantium var. amara, not the flower drug.
Citrus aurantium Blossom and Preoperative Anxiety
Randomised double-blind trial in 60 ASA I patients undergoing minor surgery. Oral Citrus aurantium blossom distillate 1 mL/kg two hours before induction reduced both Spielberger state anxiety and APAIS scores (p < 0.05), while saline placebo produced no significant change. One of the few controlled human trials using the blossom itself rather than a fruit extract.
Citrus aurantium Aroma for Anxiety in Patients with Acute Coronary Syndrome: A Double-Blind Placebo-Controlled Trial
Double-blind placebo-controlled trial of inhaled Citrus aurantium blossom aroma in patients admitted with acute coronary syndrome, reporting a significant reduction in anxiety scores versus placebo. Inhalation exposure, so it carries no implication about the sympathomimetic effects of an oral synephrine-containing dose.
Scavenging Glyoxal and Methylglyoxal by Synephrine and Neohesperidin from Flowers of Citrus aurantium L. var. amara Engl. in Mice and Humans
Synephrine and neohesperidin from the flowers of this exact variety trapped the reactive dicarbonyls glyoxal and methylglyoxal, with the resulting adducts detected in mice and in human subjects after ingestion. Mechanistic work on an anti-glycation effect; not a clinical outcome trial.
Various Antioxidant Effects Were Attributed to Different Components in the Dried Blossoms of Citrus aurantium L. var. amara Engl
Total flavonoids, alkaloids, polysaccharides, coumarins and neroli oil were separately extracted from the dried blossoms. Hesperidin, naringin and neohesperidin made up 83.94% of the flavonoid fraction and synephrine 50.56% of the alkaloid fraction. The flavonoid fraction had the strongest DPPH scavenging, FRAP and reducing power; the alkaloid fraction had the highest ABTS scavenging. This is the source of the compositional figures used above and is specific to the dried flower drug.
References
- Fugh-Berman A, Myers A. Citrus aurantium, an Ingredient of Dietary Supplements Marketed for Weight Loss: Current Status of Clinical and Basic Research . Experimental Biology and Medicine (2004) [DOI]
- Seyyedi-Mansour S, Donn P, Barciela P, Perez-Vazquez A, Nogueira-Marques R, Chamorro F, Carpena M, Prieto MA. Citrus aurantium Flowers: Overview of Chemistry, Functionality, and Technological Applications . Molecules (2025) [DOI]
- Yu L, Chen M, Liu J, Huang X, He W, Qing Z, Zeng J. Systematic Detection and Identification of Bioactive Ingredients from Citrus aurantium L. var. amara Using HPLC-Q-TOF-MS Combined with a Screening Method . Molecules (2020) [DOI]
- Pellati F, Benvenuti S, Melegari M, Firenzuoli F. Determination of adrenergic agonists from extracts and herbal products of Citrus aurantium L. var. amara by LC . Journal of Pharmaceutical and Biomedical Analysis (2002) [DOI]
This information is for educational purposes only and is not intended to replace professional medical advice. Always consult a qualified healthcare provider before using any herbal remedy, especially if you are pregnant, nursing, or taking medications.
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