Chen Pi (literally 'aged skin') is the dried peel of Citrus reticulata, traditionally aged for at least three years — and sometimes decades — before use in Chinese herbal medicine. Aging transforms the bitter, oily fresh peel into a mellow, complex remedy with a distinctly different flavour and enhanced medicinal profile. It is one of the most widely used herbs in the entire TCM pharmacopoeia and appears in dozens of classical formulas.

Chen Pi's flavonoids — especially hesperidin, nobiletin, and tangeretin — calm inflammation in the gut lining, stimulate digestive enzyme secretion, and help relax the smooth muscle of the gastrointestinal tract to relieve spasm and gas. The aromatic essential oils (mainly limonene) also directly stimulate stomach acid and bile flow, making food easier to break down. Synephrine provides mild adrenergic activity that can gently raise metabolic rate.

Traditional use calls for simmering the dried peel in water as a decoction or steeping it as a tea, which extracts both water-soluble flavonoids and aromatic oils. Modern products include standardised capsules (often standardised to hesperidin or PMF content), liquid extracts, and powders. TCM formulas frequently combine Chen Pi with other herbs such as Ban Xia, Fu Ling, or Bai Zhu. For cooking or culinary use, aged peel can be crumbled into soups, rice, and braised dishes.

• Bloating and gas
• Nausea and upset stomach
• Indigestion and poor appetite
• Phlegmy cough and chest congestion
• High cholesterol
• Inflammation and metabolic health
• Sluggish metabolism / weight management
• Acid reflux and gastric discomfort
• Liver health support

• Cardiovascular disease risk factors (via LDL and triglyceride reduction with regular long-term use)
• Post-meal blood sugar spikes (flavonoids slow carbohydrate absorption and improve insulin sensitivity)

• Aged tangerine / mandarin peel (Xinhui Chen Pi) — The herb itself — sun-dried and aged peel of Citrus reticulata — this is the direct source, and quality improves significantly with years of aging.
• Fresh tangerine / mandarin peel — Contains the same flavonoids (hesperidin, nobiletin, tangeretin) and essential oils but in a less concentrated, less medicinally active form than properly aged Chen Pi.
• Clementine and orange peel — Close botanical relatives with similar flavonoid profiles — clementines are especially high in nobiletin and tangeretin, the most researched PMFs.
• Grapefruit (white pith and peel) — Rich in naringenin and hesperidin, two of the main active flavonoids shared with Chen Pi, supporting similar digestive and anti-inflammatory pathways — but note grapefruit interactions with medications.
• Lemon peel (zest) — Contains limonene and hesperidin, contributing to similar digestive-stimulating and anti-inflammatory effects, and is easy to add to cooking or tea daily.

• Heartburn or acid reflux at high doses (particularly in those already prone to reflux)
• Mild nausea if taken on an empty stomach in large amounts
• Elevated heart rate or restlessness in sensitive individuals (due to synephrine — more relevant with concentrated extracts)
• Headache at very high doses
• Allergic reaction (rare) — possible in people with citrus allergies
• Potential blood pressure elevation in cardiovascular-sensitive individuals with concentrated synephrine-rich products

• Recommended daily: Traditional decoction: 3–9g of dried peel per day simmered in water. Standardised extract/capsule: 500–1,500mg per day of a 10:1 extract, or as directed on the product label. For PMF-standardised extracts (nobiletin/tangeretin focus): 250–500mg daily.
• Best time of day: Best taken before or with meals for digestive benefits. If using for cholesterol or metabolic support, timing is flexible — morning or midday works well.
• With or without food: Take with food or immediately before eating for digestive complaints. Can be taken without food for metabolic / anti-inflammatory purposes, though taking it with food reduces any chance of stomach upset.
• Time to effect: Digestive and nausea relief: 30–60 minutes after a tea or decoction. Cholesterol and metabolic effects: 4–8 weeks of consistent daily use.
• How long to take it: Safe for long-term daily use in traditional culinary and tea amounts. Concentrated extract supplementation is best used in 8–12 week cycles, with a break of 2–4 weeks, particularly if synephrine content is significant. Reassess goals at each cycle.