Common Names: Bitter orange, Seville orange, sour orange, zhi shi

Scientific Name: Citrus aurantium

Background

• Bitter orange originates from Southeast Asia. While the fruit is too tart to eat fresh, its peel, juice, and essential oils are often used in the culinary world, to flavor alcoholic drinks, and in fragrances.

• It is commonly marketed as a herbal supplement for weight loss, physical performance, and other health uses. The oil derived from it is also used in aromatherapy and on the skin.

• The plant contains naturally occurring compounds like p-synephrine. Although p-synephrine resembles ephedrine—previously used in weight loss products—it acts differently in the body. After ephedrine was banned by the FDA in 2004 due to safety risks, bitter orange gained popularity as a possible substitute in supplements.

• Synephrine from bitter orange is listed as a banned stimulant by the NCAA (National Collegiate Athletic Association).

How Much Do We Know?

• Research has explored bitter orange's potential for aiding in weight loss and enhancing athletic ability, but most of the studies were limited in size, quality, or looked at products containing other active ingredients as well—making it hard to isolate bitter orange’s effects.

What Have We Learned?

• There is no solid evidence that bitter orange is useful for treating any health condition.

• Its effects on reducing body weight remain uncertain. Most studies involved a small number of participants and tested products with more than one ingredient, with inconsistent findings.

• Few studies on bitter orange’s effect on athletic performance, with or without caffeine, have been conducted. Results have varied, but most showed little or no improvement.

• The use of bitter orange oil on the skin to treat conditions like ringworm or athlete’s foot has not been confirmed as effective. Existing research did not compare it to other treatments or placebos.

• Bitter orange oil is sometimes used in aromatherapy for anxiety and sleep issues. However, its actual effectiveness for these purposes is not clear.

What Do We Know About Safety?

• Bitter orange is generally safe to consume in food-level quantities. Using the essential oil on the skin or in aromatherapy also appears to be safe in most cases.

• There are major concerns about the safety of dietary supplements containing bitter orange. Serious health issues such as irregular heartbeat, heart attacks, and strokes have been reported, mostly in cases involving products with several ingredients—making it uncertain if bitter orange was the cause.

• Studies on how bitter orange affects heart rate and blood pressure show mixed outcomes—some suggest these effects exist, others do not.

• An FDA analysis of 59 bitter orange supplements revealed inconsistent levels of synephrine and related chemicals. Some products had more active compounds than expected, and a few included synthetic stimulants not legally allowed in U.S. dietary supplements.

• Anyone taking prescription medicines should check with their health care provider before using bitter orange or similar herbal supplements, as dangerous interactions can occur.

• Bitter orange should likely be avoided during pregnancy or breastfeeding. Animal studies suggest it may interfere with milk production.

Keep in Mind

• Before starting any wellness or health strategy that involves supplements or herbal products, speak with your medical team to make informed decisions together.

• Herbal products are regulated differently based on their contents and how they are used. Many are sold as dietary supplements, which are not held to the same standards as prescription medicines.

• The FDA does not review dietary supplements for effectiveness or safety before they reach the market. However, it can take action if a supplement is found to pose a danger. Producers and distributors are responsible for ensuring their products comply with all regulations regarding safety and labeling.

For More Information

• Safe use of dietary supplements

• Understanding how medications and supplements may interact

• Learning how to evaluate scientific research articles

NCCIH Clearinghouse

The NCCIH Clearinghouse provides information on integrative and complementary health approaches. It offers publications and access to scientific literature databases. Note, it does not offer medical advice or physician referrals.

Toll-free (U.S.): 1-888-644-6226

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PubMed®

PubMed® is a resource provided by the National Library of Medicine, offering details and summaries of research papers. It can help you look up scientific evidence regarding health approaches.

Office of Dietary Supplements (ODS), NIH

The ODS aims to improve public knowledge about dietary supplements by analyzing scientific data, funding research, and offering educational tools and publications.

Key References

• "Bitter orange." Drugs and Lactation Database (LactMed), National Institute of Child Health and Human Development, June 2021.

• "Bitter orange." Natural Medicines database, July 2023. [Subscription required]

• Koncz D, Tóth B, Bahar MA, et al. Study on the safety and effects of Citrus aurantium and p-synephrine. Nutrients. 2022;14(19):4019.

• NCAA. 2023-24 List of Banned Substances.

• Office of Dietary Supplements. "Dietary supplements for weight loss," July 2023.

• Pawar RS, Sagi S, Leontyev D. Examination of bitter orange supplements using LC-MS/MS. Drug Testing and Analysis. 2020;12(9):1241–1251.

• Stohs SJ, Ray SD. Study on reported adverse effects related to bitter orange and p-synephrine. Journal of Dietary Supplements. 2020;17(3):355–363.

• U.S. Food and Drug Administration. Information on methylsynephrine in supplements, August 2024.

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Information from NCCIH is meant for educational purposes and is not a replacement for medical advice. Discuss any health treatments with your healthcare provider. Mention of any specific product or therapy does not imply endorsement by NCCIH.