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Traditional Chinese medicine · Western herbalism

Orange peelCitrus reticulata (chen pi); Citrus sinensis (sweet orange); Citrus aurantium (bitter orange)

Orange and tangerine peel is the TCM herb chen pi (3 to 10 g) and a Western bitter; we could find no human trial of the peel alone for gut outcomes.

Botanical name
Citrus reticulata (chen pi); Citrus sinensis (sweet orange); Citrus aurantium (bitter orange)
Part used
dried fruit peel (rind)
Also called
pinyin Chen pi (陈皮); Tangerine peel, Mandarin peel, Bitter orange peel, Sweet orange peel
Used in
Traditional Chinese medicine, Western herbalism
Taken for
Indigestion, Bloating, Appetite, Reflux and heartburn
Sold as
capsules, tea, tincture, powder, extract, decoction

The plant

Orange peel covers three related materials. In China, chen pi is the dried mature peel of Citrus reticulata (mandarin or tangerine) and its cultivars. In Western herbalism, sweet orange peel (Citrus sinensis) is used as a mild aromatic for appetite and gas, and bitter orange peel (Citrus aurantium) as a bitter. The part used is the rind, with its colored layer and oil glands, dried in strips, powder or slices, or pressed for peel oil.

In supplements the peel appears as capsules, as a tea or tincture, as an ingredient in digestive bitters and cleanse blends, and as a powder in Chinese granule and decoction formulas. Its main constituents are flavonoids and an essential oil that is mostly D-limonene. One caution on labels: bitter orange is also sold for weight loss as a source of synephrine, a stimulant, and that use is a different product from a peel taken as a digestive tea.

How the traditions use it

Traditional Chinese medicine (about TCM)

TCM classes chen pi as warm, pungent and bitter, entering the lung and spleen channels. The Chinese Pharmacopoeia entry lists its functions as regulating qi (the tradition’s word for the movement that, when stuck, shows up as fullness and distension), fortifying the spleen, drying dampness and resolving phlegm. Its indications are epigastric and abdominal distension, poor appetite, vomiting and diarrhea, and cough with heavy phlegm. The entry gives 3 to 10 g. A meta-analysis of formulas for functional dyspepsia ranks it among the eight most-prescribed herbs.

Western herbalism

Western herbal use is for appetite, wind and acid indigestion. The Natural Medicines database lists sweet orange peel as traditionally used to increase appetite and for intestinal gas and acid indigestion, and a review of D-limonene, the main oil of the peel, says it has been used for relief of heartburn and gastroesophageal reflux on the grounds that it neutralizes stomach acid and supports normal peristalsis. These are the tradition’s reasons; neither is a trial result.

What is in it

Citrus peel contains the flavonoid hesperidin and the polymethoxylated flavones nobiletin and tangeretin, and an essential oil in which D-limonene predominates; D-limonene is generally recognized as safe as a flavoring and has low toxicity. Bitter orange peel also carries the stimulant p-synephrine, which is structurally similar to ephedrine. In an animal model of functional dyspepsia, chen pi improved body weight, gastric emptying and intestinal transit, lowered inflammatory markers and shifted gut bacteria. These are animal findings, not human trial results.

What the human trials show

We could find no controlled trial in people of orange or tangerine peel on its own for indigestion, bloating, appetite, reflux or any other gut outcome. NCCIH states that bitter orange has not been clearly shown to be helpful for any health-related purpose, and Natural Medicines gives no evidence rating for sweet orange peel’s digestive uses.

The nearest human data are formula trials. A meta-analysis of 13 randomized trials with 1,153 patients tested Chinese formulas for functional dyspepsia of the liver-stomach disharmony pattern against prokinetic drugs: the effective rate was better with the formulas (odds ratio 3.2, 95% CI 2.27 to 4.51) and the cure rate also (Peto OR 2.26), but the trials were of poor methodological quality, and chen pi was one of many herbs in the formulas, so the result cannot be credited to the peel. A randomized pilot of a fermented tangerine-peel drink in 72 people with dyslipidemia (55 completers, 8 weeks) lowered body weight and triglycerides and changed the gut microbiota, but did not measure digestive symptoms.

Laboratory work includes an animal model of functional dyspepsia in which 14 days of chen pi improved gastric emptying and intestinal transit. What has not been tested: peel against placebo for bloating, appetite or reflux; any dose comparison of aged versus fresh peel; and whether the D-limonene in peel oil changes reflux in people.

StudyDoseWhat it found
Meta-analysis of 13 randomized trials, 1,153 patients, Chinese formulas for functional dyspepsia of liver-stomach disharmony (chen pi among the most-used herbs; formulas, not peel alone; poor-quality trials) PMID 23427381Formulas, doses variedEffective rate OR 3.2 (95% CI 2.27 to 4.51) and cure rate Peto OR 2.26 versus prokinetics; no serious adverse effects reported
Randomized double-blind pilot of Chenpi Jiaosu (fermented tangerine-peel drink), 72 people with dyslipidemia, 55 completers (lipids, not gut symptoms) PMID 402253258 weeks of daily drinkLower body weight and triglycerides (p < 0.05); gut microbiota changes; no adverse effects in safety tests
Animal model of functional dyspepsia treated with Citri Reticulatae Pericarpium (not human) PMID 4001760214 days of oral peel treatment in animalsImproved body weight, gastric emptying rate and intestinal transit rate; lower IL-6, TNF-alpha and IL-1beta
Review of D-limonene safety and clinical applications PMID 18072821Not applicableLow toxicity; states use for heartburn and reflux on the basis of acid-neutralizing effect and peristalsis; no controlled trial presented in the abstract
NCCIH review of bitter orange evidenceNot applicableNot clearly shown to be helpful for any health-related purpose; serious cardiovascular events reported with multi-ingredient synephrine products

How much the studies and the texts used

The Chinese Pharmacopoeia dose for dried chen pi is 3 to 10 g; the 2015 edition of the entry notes it is added late in a decoction. No trial gives a dose of peel for digestive outcomes, and Natural Medicines lists no peel dose. The Chinese formula trials used multi-herb formulas whose peel content is not separated out, and the fermented tangerine-peel drink was taken daily for 8 weeks. Peel is also sold as capsules, tea and tincture, and bitter-orange products labeled for synephrine are dosed for a different purpose.

Doses here describe what studies and pharmacopoeias used. They are not a recommendation for any person; a clinician or pharmacist who knows your medicines and conditions is the right person to ask.

Side effects and cautions

Natural Medicines says sweet orange seems safe for most adults, safe in usual food amounts in pregnancy and breastfeeding, and that in children taking large amounts of sweet orange peel is unsafe. NCCIH rates oral bitter orange in food amounts as likely safe, says it may not be safe in pregnancy or breastfeeding, and reports serious events including abnormal heart rhythms, heart attacks and strokes, mostly with multi-ingredient products containing synephrine. FDA testing found some bitter orange products contained undeclared synthetic amines. The Chinese Pharmacopoeia entry lists no cautions. The formula meta-analysis reported no serious adverse effects, and the dyslipidemia pilot found none in safety blood and urine tests.

Interactions

The interactions on record come from citrus juice, not peel. Natural Medicines says sweet orange may affect OATP transporters and P-glycoprotein pumps and change the absorption of some medicines, and rates celiprolol, ivermectin and pravastatin major, with fexofenadine and P-glycoprotein substrates such as cyclosporine moderate; it suggests separating doses by at least four hours for celiprolol and OATP drugs. The site’s own rules also list atenolol, montelukast, rosuvastatin, methotrexate, digoxin, tacrolimus and several anticoagulants, each marked theoretical and juice-based. NCCIH says some studies of bitter orange with synephrine found higher blood pressure and heart rate and others did not.

Medicines the quiz checks orange peel against

When a quiz taker names one of these medicines, the rule below fires. Each comes from a published interaction reference; none is a diagnosis:

Orange peel on the shelf: the products that contain it

The products here name orange peel among their actives. How much of it a serving holds, and whether that matches any trial, is on each page.

Urban Moonshine Original Digestive Bitters 4.4 out of 5 from 1,409 ratings from Amazon · $0.68 a day Renew Life PARA SMART Cleansing Formula, 15-Day Program 4.2 out of 5 from 1,398 ratings from Amazon · ~$2.04 a day across the full 15-day program Snap Dynasty Stomach Chi 4.5 out of 5 from 162 ratings from Amazon · $1.50 per day at two capsules three times a day ($29.99 for 120 on the brand site, $29.98 on Amazon, a 20-day bottle); the 60-capsule bottle is $17.99 Health Concerns Quiet Digestion 4.5 out of 5 from 54 ratings from Amazon · $2.39 per day at two capsules three times a day ($35.90 for 90 on the brand site and Amazon, a 15-day bottle); the 270-capsule size is $1.89 a day Health Concerns Six Gentlemen 4.4 out of 5 from 41 ratings from Amazon · $1.99 per day at two capsules three times a day ($29.90 for 90 on the brand site, $29.99 on Amazon, a 15-day bottle)

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Often paired or compared

TCM / Western Hawthorn Crataegus pinnatifida (shan zha); Crataegus monogyna and C. laevigata (Western) TCM Bitter orange Citrus aurantium Ayurvedic / TCM / Western Ginger Zingiber officinale Western Gentian Gentiana lutea Ayurvedic / TCM / Western Fennel Foeniculum vulgare

What people want to know

What is chen pi?

Chen pi is the dried peel of Citrus reticulata in TCM. The Chinese Pharmacopoeia lists it for epigastric and abdominal distension, poor appetite, vomiting and diarrhea, and cough with phlegm, at 3 to 10 g.

Has orange peel been tested for bloating or indigestion?

We could find no controlled trial of the peel on its own. Chen pi is one of the most-used herbs in Chinese formulas that beat prokinetic drugs in a meta-analysis of 13 poor-quality trials, but the trials tested whole formulas.

Is bitter orange peel the same as a bitter orange weight-loss supplement?

No. The weight-loss products are standardized for p-synephrine, a stimulant structurally similar to ephedrine, and NCCIH reports serious cardiovascular events with multi-ingredient versions. A peel taken as a digestive tea is a different product.

Does orange peel interact with medicines?

The documented interactions come from large amounts of citrus juice affecting drug transporters. Natural Medicines rates celiprolol, ivermectin and pravastatin major with sweet orange, and the site’s rules flag others as theoretical.

Is orange peel safe for children?

Natural Medicines says that in children, taking large amounts of sweet orange peel is unsafe. Food-level amounts are a different matter.

Sources