Bitter orange (Citrus aurantium): Uses, Evidence and Safety

Safety first: heart rhythm and blood pressure

Bitter orange as a flavoring in food is one thing. Bitter orange supplements, which are sold for weight loss and sports and contain a stimulant called p-synephrine, are another. NCCIH (part of NIH) says serious events, including abnormal heart rhythms, heart attacks and strokes, have been reported in people taking bitter orange supplements, but most of those products had several ingredients, so the role of bitter orange itself is unclear. [1] A 2022 meta-analysis of placebo-controlled trials found that blood pressure rose after prolonged use of synephrine and that heart rate tended to rise. [2] A 2023 review collected 30 case reports describing 35 people who became unwell after synephrine supplements. Chest pain, palpitations, fainting and dizziness were the most common problems, and five people were left disabled or stayed on medication. Caffeine and other ingredients could not be ruled out as causes. [3] If you have heart disease, high blood pressure, an irregular heartbeat or a history of stroke, or you take medicines for these, talk to your prescriber before using any bitter orange or synephrine product. Chest pain, fainting, a racing heartbeat that does not settle, or signs of a stroke need emergency care (911 in the US). See heart disease, high blood pressure and supplements.

Overview

Bitter orange is the fruit of Citrus aurantium (written Citrus × aurantium L. in the GBIF database, which lists it as an accepted species in the family Rutaceae). [5] It is also called Seville orange, sour orange and zhi shi. [1] NCCIH says it is a citrus tree native to Southeast Asia, and that the fruit is too sour to eat raw. [1] The fruit, peel and oil are used in cooking, to flavor beer and spirits, and in perfume. [1] The fruit contains p-synephrine, which looks chemically similar to ephedrine. [1] This page is about the fruit and peel and the supplements made from them. For the essential oil, see sweet vs bitter orange oil. A broader page on bitter orange, yohimbe and other stimulant herbs is also available.

Traditional use (not proof of benefit)

A 2018 review says bitter orange is used as a flavoring and acidifying agent in food, and that in traditional medicine the plant has been used for anxiety, stomach and gut problems and obesity. [6] The same review notes that oil from the flowers (neroli) has traditionally been used for palpitations, sleep and soothing the digestive tract. [6] Traditional use is not evidence that a product works or is safe, and much of the work that review cites was done in animals or in the lab. [6]

What research shows

Bitter orange has not been clearly shown to help any health condition, according to NCCIH. [1]

Studies that tested bitter orange for treating a specific disease in people with that disease: Proper evidence not found in the sources we read.

Forms and why the form matters

Bitter orange appears as a cooking and flavoring ingredient, as peel or fruit extracts, as supplements sold as "synephrine" or "p-synephrine", as the essential oil, and as a part of multi-ingredient weight-loss and pre-workout products. [1][3] These are not interchangeable. The heart and blood pressure concerns are tied to the stimulant compounds in supplements, not to the amounts used as a food flavoring, which NCCIH calls likely safe. [1] Many supplement products also contain caffeine and other stimulants, which makes it hard to know which ingredient caused a reaction. [3] How much to use is a decision for a clinician or pharmacist, not this page.

Safety in more detail

• Heart and circulation: abnormal heart rhythms, heart attacks and strokes have been reported with bitter orange supplements (mostly multi-ingredient products). [1] A 2026 case report described a 38-year-old woman with no known heart risk factors who developed a fast heart rhythm and heart-muscle injury after one week of a weight-loss supplement containing bitter orange; the authors called the link possible, not proven. [8] The favorable 2017 review argued that most earlier reports involved other ingredients such as caffeine, smoking or existing heart disease, and that synephrine acts differently from ephedrine. [7] Both views are on record, which is a reason to be careful.
• Medicines: NCCIH says some herbs and medicines interact harmfully and that anyone taking medicine should speak to a health professional first. [1] We did not find a source we could read that lists specific drug interactions for bitter orange peel. The 2017 review (see the industry note above) says standard extracts contain very little of the grapefruit-type compounds that block drug-processing enzymes, and that a small human study found no major effect on those enzymes. [7] Because products also contain caffeine and other stimulants, combinations with blood pressure, heart rhythm, thyroid or stimulant medicines, and with antidepressants, are a question for a pharmacist. See how herbs and medicines interact.
• Pregnancy: NCCIH says bitter orange supplements may not be safe in pregnancy. [1]
• Breastfeeding: NCCIH says it may not be safe, and animal data suggest it might reduce milk production. [1]
• Children and teens: Proper evidence not found in the sources we read. We could not find a source we read that supports use in children.
• Liver and kidney: NIH's LiverTox entry could not be read (the site blocked automated access), so we make no claim about liver injury either way. Kidney: Proper evidence not found in the sources we read.
• Allergy and skin: Proper evidence not found in the sources we read for the fruit or supplements. For citrus oils on skin, see sweet vs bitter orange oil.
• Surgery: Proper evidence not found in the sources we read. Because of the heart and blood pressure concerns, tell the surgical team about any stimulant supplement. See supplements before surgery.
• Quality and contamination: FDA researchers tested 59 products labeled as containing bitter orange. Several held more amines (stimulant-type compounds) than expected from a normal extract. Of 23 products that stated a synephrine amount, only 5 were within 80 to 120 percent of the label. Six contained methylsynephrine and one contained isopropyloctopamine, synthetic stimulants that are not permitted in dietary supplements and whose effects in people are not known. [4][1] See product quality and contamination.
• Sport: NCCIH notes the NCAA lists synephrine (bitter orange) as a banned stimulant. [1]

Official statements

• NCCIH (US), page updated November 2024: bitter orange has not been clearly shown to help any health condition; serious events have been reported with supplements; the fruit and oil are likely safe in food amounts and in aromatherapy or on the skin. [1]
• FDA (US), 2004: after the agency banned ephedra alkaloids in dietary supplements, bitter orange became a popular replacement, as NCCIH describes. [1]
• FDA researchers, 2020: analysis of 59 supplements found label inaccuracies and synthetic stimulants in some. [4]
• EU (EMA): Proper evidence not found in the sources we read. A search suggested the EU herbal committee has not issued a single-ingredient monograph for bitter orange peel, but we did not read the EMA's list ourselves.

Related pages

• Bitter orange, yohimbe and other stimulant herbs
• Ephedra (ma huang) and other banned herbal ingredients
• Herbs for weight loss: claims checked
• Sweet vs bitter orange oil
• Supplements and blood pressure and heart medicines
• Product quality and contamination