Bitter orange

Bitter orange is used in herbal medicine in various forms and preparations. This includes the dry unripe fruit, ripe fruit, fruit peel, leaves, flowers and seeds.

This monograph mainly focuses on the use of orange flower as used in herbal medicine. Orange flower is used in Western herbalism and also traditional Chinese medicine (TCM). Orange peel, fruit and leaf also have medicinal and nutritional benefits of their own, some of which have been included in this monograph.

Orange flower is a gentle nervine herb that can be used to help with stress and tension. It is both a relaxant and mild sedative, which can bring about a sense of calm in times of heightened stress or acute anxiety (1). The aromatic water (hydrosol), tea or tincture can all be used as a daily support to offer its calming, harmonising effect to the nervous system.

In TCM, orange flower is used to regulate the flow of qi (qi relates to vital energy or life force that is thought to guide physical, spiritual and mental processes). Orange flower also works on the digestive system, assisting in smooth digestive processes due to its carminative and antispasmodic actions. It can be used to help with abdominal pain, indigestion and flatulence (2,3).

Orange flower has a clearing and opening effect due to its expectorant action. This makes it useful in the removal of phlegm and mucous experienced with the common cold or in cases of respiratory congestion (2). Orange flower also has a mild diuretic effect, which can be applied to help clear congestion throughout the body (2). Diuretics promote the elimination of fluid via the urinary system and, therefore, help to reduce excess or retained fluids that accumulate in the tissues. The combination of this herb’s cleansing and regulating effects make it a choice medicine for convalescence and recovery from acute illness.

Bitter orange fruit peel also has its own medicinal applications. It is used in abdominal and digestive discomfort and bloating. The rind can also be used to help treat nausea and indigestion (1). This can be used fresh or dried and blended in with other herbs such as fennel (Foeniculum vulgare), ginger (Zingiber officinale) or lemon balm (Melissa officinalis) to support digestion.

Two essential oils are also produced from the bitter orange plant: neroli which is made from the flowers; and petitgrain, which is made from the twigs and leaves. These both have their own unique aromatic qualities as well as therapeutic applications. Yet, they both are indicated for anxiety, stress and nervous tension.

Orange flower has bitter and cooling qualities. It is understood to have gently stimulating effect on the liver. The liver is a vital organ that has an important role in blood detoxification and metabolism. Orange flower’s gentle effect on the liver helps to reduce systemic heat and toxicity throughout the body (1).

Aromatic herbs are invaluable as part of any prescription and may also find their way into medicines to harmonise the medicine and connect the emotional and physical centres. Aromatic oils are either stimulating or relaxing and support efficient circulation. A herbalist may use orange flower as part of a formula to assist in increasing blood flow and deliverance of other herbs and their active constituents to the tissues where they are needed. Aromatic herbs are sometimes described as ‘carrier remedies’ as they potentiate the effects of other herbs. 

Andrew Stableford describes orange flower in his book,  Handbook of Energetic and Constitutional Herbal Medicine, as a herb that has a calming effect on the central nervous system (4). It can be used for support in challenging or difficult circumstances to help maintain a sense of calmness and integrity (4). 

Stableford describes orange flower as a herb that “clears emotional impressions and tension”. This herb is, therefore, sometimes included in medicinal prescriptions as an emotional ‘facilitator’ (4).

Orange flower has an emotional application where personal transformation is involved. Stableford writes that such herbs can “remove complexes or internalised and unresolved emotional issues giving a sense of resolution and peace”. It can have a resolving or liberating effect on emotional structures related to important life events (4). In contrast to earlier texts, Stableford described bitter orange flower as energetically warming and moistening. This nuance is sometimes seen across different energetic systems or even from herbalist to herbalist. It reflects the intersection between traditional and modern interpretations as well as the unique relationships that are held by a practitioner and the herbs they work with.

The distilled flower water is antispasmodic and relaxant. This can be used as a refreshing and calming spritz to tone and cool the skin, helping to brighten the complexion (5).

Citrus plants offer a bounty of healing potential in traditional Chinese medicine (TCM). The fruit of the bitter orange tree provides two indispensable TCM herbs for regulating the qi, or life force, of the body where impediment of its natural flow has impacted the abdomen or chest. 

Zhi shi, the immature fruit of the bitter orange tree, is harvested in late spring to early summer before it ripens and is an energetically bitter, pungent and slightly cold herb. This combination of properties encourages the movement of qi, guides energy downwards and clears phlegm. As it enters the Spleen, Stomach and Large intestine organ systems, it is an invaluable herb for alleviating food stagnation, constipation and difficult diarrhoea with gas, bloating and discomfort. Its powerful qi-moving and phlegm-clearing abilities also benefit xiong bi — painful obstruction of the chest, as seen in angina and other coronary heart disorders. 

Zhi ke is the mature bitter orange fruit. The ripening process adds a little warmth to this herb, which is cool and bitter in nature, making it a milder medicinal and, therefore, more appropriate in cases of weakness (6).

Bitter orange has a rich history of use in many cultures and traditions of herbal medicine around the world. In India, the peel is believed to have laxative effects and is also used traditionally as a stomachic and emmenagogue. The dried rinds also have a traditional use for atonic dyspepsia (5).

Aqueous extract (hydrosol) of orange flower was used to treat scurvy, fever and in cases of an enlarged spleen. Many traditional references also exist for the application of orange flower hydrosol in nervous and hysterical disorders due to its calming and relaxant properties. A decoction of the fruit and rind was used to assist in the recovery from cachexia (weakness and wasting) associated with chronic illness and intermittent fever (5).

In traditional Persian medicine, bitter orange flower and peel are used in the form of a hydrosol, to offer benefits to the nervous system with reference to neuroprotective and antidepressant effects (5). It is also believed to possess aphrodisiac properties and is believed to support liver function. Further to this, bitter orange hydrosol is used internally to treat bloating, dyspepsia, diarrhoea and polymenorrhea (5).

The fruit of the bitter orange tree is a classical herb in traditional Chinese medicine for regulating qi, its use dating back as far as the 2nd century CE where it is first mentioned in the Shen Nong Ben Cao Jing (Classic of the Materia Medica), TCM’s earliest text detailing individual herbs. Its primary traditional therapeutic use is to alleviate stagnation of qi in the abdomen and chest, in particular alleviating discomfort from stagnation in the digestive system. As the Ben Cao Gang Mu (Great Pharmacopoeia), a 16th century TCM text states: “zhi zhi can chase out accumulated food, eliminate phlegm and clear through constipation” (6)

Nervous system

Herbalists commonly use orange flower in the treatment of conditions for the nervous system. Some of the properties that lend themselves to nervous disorders stem from its relaxing action on the nervous system; however, orange flower is also thymoleptic (a mood enhancer). Orange flower can bring a sense of vitality. With these balancing and uplifting effects orange flower could be considered as part of a treatment approach for depressive tendencies (4).

Orange flower’s relaxant effects are often employed for anxiety and nervous tension. It is used to help bring a sense of calm and clarity in times of stress. As such, it can be used for stress-related conditions of the mind, particularly for those associated with heightened, overactive or anxious states (4). Whilst these calming and invigorating actions appear contradictory, this is a classic example of herbal medicine’s ability to moderate and balance. 

Orange flower combines well with motherwort (Leonurus cardiaca) and skullcap (Scutellaria lateriflora) for anxiety-related conditions. Herbalists often incorporate nerve tonics and regenerative nervines into a medicine for treating nervous debility, anxiety or depressive states. This would include the use of herbs like oat straw (Avena sativa) or ashwagandha (Withania somniferum).

It may also be useful as part of a treatment approach for stress-related tension headaches and digestive disturbances. This would be most applicable where these symptoms are associated with anxiety, trauma and nervous tension (4).

The presence of aromatic compounds may hold some relevance to orange flower’s nervine action. Neroli essential oil (a pure extract of orange flower volatile oils) is primarily used for stress and its associated ill effects, such as insomnia, panic attacks or anxiety. These effects have been demonstrated in clinical studies for postmenopausal women (7). The anxiolytic effects of neroli essential oil have also been demonstrated in a clinical study relating to anxiety and stress surrounding childbirth (8). 

Orange flower also has antispasmodic effects which may contribute to the mechanism of action for relaxant effects throughout the nervous and digestive systems 4).

Cardiovascular system

Orange flower may be used as part of an approach to treat hypertension (high blood pressure) and palpitations (4). This is most relevant when these conditions are associated with chronic stress exposure.

Endocrine system

Orange flower may be of use as part of a herbal formula for improving cellular health. This is due to its powerful antioxidant and free radical scavenging activity. These actions have  been identified through recent scientific research (9). The fruit is commonly known to have antioxidant properties as it is high in vitamin C, carotenoids and flavonoids .

Orange peel is sometimes used as part of a treatment approach for obesity and weight loss. It contains a compound called synephrine — a stimulant with similar properties to caffeine and ephedrine. Its effects are thought to be due to increasing energy expenditure and metabolism as well as suppressing the appetite. It has become a widely used stimulant in supplements purporting weight loss claims(10).

Digestive system

Zhi shi (dried bitter orange fruit) is one of the strongest and most important herbs in the TCM materia medica for gastrointestinal conditions stemming from stagnation. As with most TCM herbs, zhi shi is typically prescribed in synergistic combinations of herbs within a herbal formula. 

For food stagnation with gas and bloating, it is often combined with herbs that primarily relieve food stagnation such as shan zha (Crataegus monogyna, hawthorn fruit) and mai ya (Hordeum vulgare, barley sprout). 

In cases where weak digestive energy (what is known in TCM as a Spleen and Stomach qi deficiency) has led to gas and bloating after eating due to improper processing of food and drink, zhi shi will be combined with tonic herbs such as bai zhu (Atractylodes macrocephala, atractylodes) that address the underlying weakness.  

The pairing of zhi shi and tonics such as bai zhu is also used for appropriate cases of rectal or uterine prolapse as it fortifies the energy needed to hold the organs in place whilst alleviating the root cause of qi stagnation and its associated discomfort.

For constipation and dysenteric diarrhea that is hard to evacuate, zhi shi will often be paired with the purgative herb, da huang (Rheum palmatum, rhubarb).   

It is also a leading TCM herb for epigastric distension and discomfort associated with inflammation of the gall bladder (cholecystitis), and in such cases will be prescribed alongside herbs beneficial to the Liver and Gallbladder that also alleviate qi constraint such as chai hu (Bupleurum falcatum).  

On account of its slightly cold nature, zhi shi is most appropriate in cases where there is heat in the body. It is sometimes dry-fried prior to prescription to alleviate some of its coolness and to protect digestion. As it strongly spreads qi, it is not advised in cases of weakness where fragile energy may be dispersed, exacerbating the condition (6). 

There are currently no clinical trials on orange flower extracts. However, there are a small number of in vitro studies that explore the effects of its compounds. More studies exist on the effects of orange flower essential oils than that of extracts as used in herbal medicine. A number of these studies have been included below to demonstrate the mechanism of action for some of the medicinal virtues discussed in this monograph. These works, although limited, afford us some insight into the medicinal activities of orange flower and its counterparts.

Animal studies are not condoned by Herbal Reality, however for the purpose of including research from which some understanding of therapeutic actions can be confirmed, some animal studies may have been referenced within the works included herein.

Chemical profile and antioxidant potency of Citrus aurantium L. flower extracts with antibacterial effect against foodborne pathogens in rice pudding

An in vitro study was carried out to analyse the antioxidant and antibacterial activities of orange flower extracts. The study evaluated antimicrobial effects against inoculated test pathogens in rice pudding for seven days at 8 °C. The findings showed that a methanol extract demonstrated the highest antimicrobial activity against Staphylococcus aureus. The extract also exerted these effects on other bacterial strains such as Escherichia coli, Salmonella typhimurium, Listeria monocytogenes and Bacillus cereus (11).

Methanol extract of orange flower decreased the growth rate of all tested pathogens and natural flora. The study may provide some grounds for further investigation of orange flower for use as a bioactive agent in both food and medicine industries (11).

Another in vitro study was carried out to explore antioxidant effects of orange flower extracts. The study demonstrated powerful scavenging activity against free radicals. The study evaluated the effects of orange flower bioactive compounds identifying polyphenolic compounds (12).

Biological actives of orange flower extract

A further study set out to evaluate orange flower phenolic and flavonoid activities specific to its antioxidant, anti-inflammatory and anticancer effects. In vitro methods used in this analysis demonstrated anti-inflammatory properties when applying a methanolic extract. These results followed application of the extract to human cells and identified a reduction in nitric oxide production (13).

The anticancer activities of the methanolic extract were then investigated using in vitro methodology against human cancer cell lines, human colon adenocarcinoma and Chang liver cells as a representation of a normal human hepatocyte. This exercise showed moderate to significant activities against all cell lines (13). These findings offer preclinical insight only. Results from in vitro studies are not sufficient to support clinical use. For those seeking to support during cancer treatment, it is advised to work with an integrative oncology specialist as treatment is nuanced and case specific.

Orange flower essential oil double blind controlled trial for anxiety in patients with acute coronary syndrome

A randomised double blind placebo controlled trial was carried out to investigate the anxiolytic effect of inhaled orange flower essential oil (neroli oil) on patients with acute coronary syndrome (ACS). A total of 140 hospitalised ACS patients were randomly assigned to receive orange flower essential oil or a placebo (paraffin) administered three times a day.

The oil contained 30% essential oil of Citrus aurantium flowers in paraffin. The study results demonstrated that the neroli oil group anxiety score was significantly lower than that of the placebo group (14).

Oranges can produce flowers and fruit at the same time. This has led to them becoming a symbol of fertility.

The fruits of bitter orange are most commonly used for making marmalade. It is also used in a number of liqueurs, such as Triple Sec.

Bitter orange is an artificial hybrid of Citrus reticulata and Citrus maxima. It, therefore, doesn’t have a native range but it is widely cultivated throughout the world (20). 

Its parent species were likely native to Southeast Asia, Eastern Africa and the Arabian Peninsula. It is now cultivated throughout the Mediterranean region, California and Florida as well as other countries. It typically grows in subtropical to near-tropical climates (20).

Bitter orange has not yet been assessed for the IUCN Red List of ‘at risk’ species, therefore there is insufficient data to confirm its sustainability status (21). Bitter orange is an artificial hybrid and widely cultivated around the globe for use as food and medicine (22). 

Habitat loss and over-harvesting from the wild are two of the biggest threats faced by medicinal plant species. There are an increasing number of well-known herbal medicines at risk of extinction. We must, therefore, ensure that we source our medicines with sustainability in mind.

The herb supplement industry is growing at a rapid rate and until recent years a vast majority of medicinal plant produce in global trade was of unknown origin. There are some very real and urgent issues surrounding sustainability in the herb industry. These include environmental factors that affect the medicinal viability of herbs, the safety of the habitats that they are taken from, as well as the welfare of workers in the trade.

The botanical supply chain efforts for improved visibility (transparency and traceability) into verifiably sustainable production sites around the world is now certificated through the emergence of credible international voluntary sustainability standards (VSS). 

Read our article on Herbal quality & safety: What to know before you buy and Sustainable sourcing of herbs to learn more about what to look for and questions to ask suppliers about sustainability.

Herbal medicines are often very safe to take; however, their safety and efficacy can be jeopardised by quality issues. So, it is important to buy herbal medicines from a reputable supplier, from sources known to test their herbs to ensure there is no contamination, adulteration or substitution with incorrect plant matter, as well as ensuring that recognised marker compounds are at appropriate levels in the herbs.

Some important quality assurances to look for are certified organic labelling, the correct scientific/botanical name, and the availability of information from the supplier about ingredient origins. A supplier should be able to tell you where the herbs have come from, what contaminants are not in the herb, and what the primary compounds are.

Bitter orange is fairly easy to grow. It is a resilient plant that can tolerate adverse conditions including drought. It can adopt a wide range of soil conditions and requires little care providing the location requirements are met. It grows best inside a large pot.

Bitter orange prefers a bright location out of any draught or extreme cold or sun exposure. During the warm summer, potted shrubs can be placed out in the garden. Move indoors during the colder months of winter.Potted bitter orange will grow up to two metres, which makes it easy to move between summer and winter. Take note that citrus plants dislike being repotted so ensure that the correct soil substrate is used in its final growing environment (23).

High-quality universal soil is suitable as a plant substrate. It can be mixed with one third of expanded clay for optimum soil aeration. There are specific composts made for citrus plants as an alternative. The best soil pH type is slightly acidic to allow for healthy growth.

Bitter orange requires a lot of water and the root ball should not dry out. Waterlogging should also be avoided. It is best to water bitter orange early in the morning or late in the evening as during the hot midday sun the water may evaporate and lead to inefficient moisture in the root ball. Low-lime water is preferable to maintain soil pH for optimum growth. Collected rainwater or mineral water are suitable.

When the leaves start to turn a light green colour, it is time for fertilisation. Fertilise once a week with a fertiliser specifically adapted to the needs of citrus plants.

To prune and shape the plant and promote new growth, cut back once a year in the spring before the start of vegetation, as this is when pruning cuts heal best. Young plants develop a compact crown after about two to three years (23). 

Orange flower hydrosol

A hydrosol is an aqueous extract used in herbal medicine. It can be taken as an internal medicine, as well as used topically and cosmetically. Hydrosols are made via steam distillation usually using aromatic herbs, either fresh or dried.

The plant material is added to boiling water and then reduced to a simmer, to create steam. The steam is a product of the plant material in distilled water, which then rises to the top after passing through ice (which cools it down — preserving the highest amount of aromatic compounds). 

The collected condensate of this steaming process is what makes the hydrosol. The essential oil floats on the surface and the remaining water is the true hydrosol.

Hydrosols are highly aromatic, containing many therapeutic properties of their corresponding essential oil as well as some of the bioactive compounds and properties of the whole plant, as used in herbal medicine.

Orange flower hydrosol ingredients

To make a hydrosol you will need:

• 1 large pot with lid
• 1 large heat-safe bowl
• 1 smaller heat-safe bowl
• Ice
• Freezer bag
• Distilled or spring water
• 5–6 cups of dried or fresh plant material (orange flower in this case)

How to make orange flower hydrosol

1. Place the large heat-safe bowl in the centre of the large pot, upside-down with the smaller bowl placed up facing on top (the smaller bowl will collect the hydrosol). 
2. Place your orange flowers around the sides of the larger bowl and then cover with water no higher than the top of the large bowl.
3. The pot lid can now be placed onto the large pot (upside down). Fill a large freezer bag or similar with ice. Seal and place on top of the pot lid.
4. Bring the water to a boil and then reduce to a simmer for 30 minutes replacing the bag of ice if it melts.
5. After 30 minutes the smaller bowl will contain the hydrosol. The lid can now be removed and the smaller bowl carefully removed. Pour the collected water into a sterile amber, blue or green glass bottle.
6. Label with the date and then store in the fridge for the longest shelf life. Use freely in recipes or as a refreshing facial tonic.

1. Kenner D, Yves Requena. Botanical Medicine : A European Professional Perspective. Paradigm Publications; 2001.
2. Holmes P. The Energetics of Western Herbs. Snow lotus press; 2020.
3. Bensky D, Clavey S, Stöger E. Chinese Herbal Medicine. Materia Medica. 3rd ed. Eastland Press; 2015.
4. Stableford A. The Handbook of Constitutional and Energetic Herbal Medicine the Lotus Within. Aeon Books; 2021.
5. Memariani Z, Gorji N, Moeini R, Farzaei MH. Traditional uses. Phytonutrients in Food. Published online 2020:23-66. https://doi.org/10.1016/b978-0-12-815354-3.00004-6 
6. Chan Y. Understanding Chinese Herbs.; 1996.
7. Choi SY, Kang P, Lee HS, Seol GH. Effects of Inhalation of Essential Oil of Citrus aurantium L. var. amara on Menopausal Symptoms, Stress, and Estrogen in Postmenopausal Women: A Randomized Controlled Trial. Evidence-based Complementary and Alternative Medicine : eCAM. 2014;2014. https://doi.org/10.1155/2014/796518 
8. Scandurra C, Mezzalira S, Cutillo S, et al. The Effectiveness of Neroli Essential Oil in Relieving Anxiety and Perceived Pain in Women during Labor: A Randomized Controlled Trial. Healthcare. 2022;10(2):366. https://doi.org/10.3390/healthcare10020366 
9. Değirmenci H, Erkurt H. Relationship between volatile components, antimicrobial and antioxidant properties of the essential oil, hydrosol and extracts of Citrus aurantium L. flowers. Journal of Infection and Public Health. Published online July 2019. https://doi.org/10.1016/j.jiph.2019.06.017 
10. Stohs SJ, Preuss HG, Shara M. A Review of the Human Clinical Studies Involving Citrus aurantium (Bitter Orange) Extract and its Primary Protoalkaloid p-Synephrine. International Journal of Medical Sciences. 2012;9(7):527-538. https://doi.org/10.7150/ijms.4446 
11. Degirmenci H, Erkurt H. Chemical profile and antioxidant potency of Citrus aurantium L. flower extracts with antibacterial effect against foodborne pathogens in rice pudding. LWT. 2020;126:109273. https://doi.org/10.1016/j.lwt.2020.109273 
12. Mansour SS, Noel F, Donn P, Barciela P, Cassani L. Exploring the potential of Citrus aurantium L. flowers as a source of antioxidant compounds. Published online November 1, 2022. https://www.researchgate.net/publication/366346992_Exploring_the_potential_of_Citrus_aurantium_L_flowers_as_a_source_of_antioxidant_compounds 
13. Karimi E, Oskoueian E, Hendra R, Oskoueian A, Jaafar HZE. Phenolic Compounds Characterization and Biological Activities of Citrus aurantium Bloom. Molecules. 2012;17(2):1203-1218. https://doi.org/10.3390/molecules17021203 
14. Moslemi F, Alijaniha F, Naseri M, Kazemnejad A, Charkhkar M, Heidari MR. Citrus aurantiumAroma for Anxiety in Patients with Acute Coronary Syndrome: A Double-Blind Placebo-Controlled Trial. The Journal of Alternative and Complementary Medicine. 2019;25(8):833-839. https://doi.org/10.1089/acm.2019.0061 
15. Chen JK, Chen TT, Crampton L. Chinese Medical Herbology and Pharmacology. Art Of Medicine Press, Inc; 2004.
16. Natural Medicines. Bitter orange. naturalmedicines.therapeuticresearch.com. Published 2024. https://naturalmedicines.therapeuticresearch.com/databases/food 
17. Suryawanshi J. An overview of Citrus aurantium used in treatment of various diseases. African Journal of Plant Science. 2011;5(7):390-395. https://academicjournals.org/article/article1380019714_Suryawanshi.pdf 
18. Maksoud S, Abdel-Massih RM, Rajha HN, et al. Citrus aurantium L. Active Constituents, Biological Effects and Extraction Methods. An Updated Review. Molecules. 2021;26(19):5832. https://doi.org/10.3390/molecules26195832 
19. Royal Botanical Gardens Kew. Bitter orange – Citrus × aurantium | Plants | Kew. www.kew.org. Published 2024. https://www.kew.org/plants/bitter-orange 
20. Royal Botanical Gardens Kew. Citrus × aurantium L. | Plants of the World Online | Kew Science. Plants of the World Online. Published 2016. Accessed March 28, 2025. https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:59600-2#distributions 
21. IUCN Redlist. The IUCN Red List of Threatened Species. IUCN Red List of Threatened Species. Published 2025. Accessed March 28, 2025. https://www.iucnredlist.org/search?query=citrus%20aurantium&searchType=species 
22. Hisashi Kato-Noguchi, Kato M. Pesticidal Activity of Citrus Fruits for the Development of Sustainable Fruit-Processing Waste Management and Agricultural Production. Plants. 2025;14(5):754-754. https://doi.org/10.3390/plants14050754 
23. Fredrik. Bitter orange: growing Seville oranges – Plantura. Plantura. Published April 14, 2022. Accessed March 28, 2025. https://plantura.garden/uk/fruits/bitter-orange/bitter-orange-overview