Fo Shou (Finger Citron Fruit)

Chinese Herb Actions

Chinese Herb Dosage

• What is the typical dosage of Fo Shou?

  Roughly 3–9 g in decoction (Bensky), or 3–10 g (Chen & Chen) — a small, conventional range for a qi-regulating aromatic. Like other fragrant qi herbs, its active volatile oil is driven off by prolonged boiling, so it is customarily added late in the decoction rather than cooked from the start. The dried slices are also commonly steeped as an infusion or taken as a candied/steeped preparation in food use.

  • Decoction — 3–9 g (Bensky) / 3–10 g (Chen & Chen), added toward the end of cooking to preserve the aromatics.
  • Processing note — a steamed form is used in parts of Guangdong; processing research reports that steaming shifts the aroma profile and the herb’s “drying” character, so raw and steamed material are not strictly interchangeable.

  Source: Sacred Lotus sources & references (Bensky and Chen & Chen ranges as recorded on file); processing note from PMID 41674693 and PMID 42011609. Reference only — not a prescription.

Chinese Herb Contraindications & Cautions

• Are there cautions for Fo Shou?

  Use with caution in yin deficiency with fire. Fo Shou is warm, aromatic and drying by nature, and the standard caution across the qi-regulating category is that such herbs can further consume fluids and yin. It is otherwise a mild herb with a long food history and no distinctive contraindication of its own.

  • Yin deficiency with heat/fire — caution; the drying, aromatic character is not well suited to depleted fluids.
  • Qi deficiency without stagnation — as with the qi-regulating category generally, moving herbs are not indicated where there is nothing to move.
  • Pregnancy — no specific traditional prohibition is recorded for Fo Shou, but qi-moving herbs are generally used only under professional supervision in pregnancy.
  • Photosensitivity (reference note) — citron peel, like other citrus peels, contains furanocoumarins, a compound class associated with phototoxic skin reactions on direct skin contact with the fresh peel or its essential oil. This is a topical/handling consideration reported for citrus peel oils generally, not a documented effect of the decocted herb.

  Source: Sacred Lotus sources & references (recorded caution); qi-regulating category cautions per materia medica consensus; furanocoumarin/phototoxicity context from PMID 28581738 and PMC 8070520. Reference note, not a safety guarantee.

Chinese Herb Toxicity & Overdose

• Low. Fo Shou is classed as a “medicine and food homology” material in China — it is eaten candied, brewed as a tea and used as a flavouring — and no significant toxicity is reported at normal medicinal doses. No specific toxic constituent or dose ceiling is recorded for it in the sources reviewed.

  Source: materia medica consensus; food-use status noted across the research literature (e.g. PMID 40490235). Reference note, not a safety guarantee.

Herb-Drug Interactions

• Does Fo Shou interact with medications — is it like grapefruit juice?

  No clinical herb–drug interaction study of Fo Shou exists, and the grapefruit story should not simply be transferred to it — but the caution is not baseless either, because furanocoumarins have been documented in Fo Shou. The grapefruit–drug effect is driven by specific furanocoumarins, chiefly bergamottin and 6′,7′-dihydroxybergamottin, which irreversibly inhibit intestinal CYP3A4; naringin separately inhibits the OATP1A2 transporter. These constituents vary enormously between citrus species and cultivars, so “citrus” is not a single interaction category.

  • What is documented for Fo Shou specifically — a pharmacokinetic study of Citri Sarcodactylis Fructus found that bergapten, bergaptol, oxypeucedanin and byakangelicol were absorbed into rat plasma after dosing, alongside simple coumarins such as 5,7-dimethoxycoumarin (limettin) and scoparone. Bergapten is a furanocoumarin, and furanocoumarins as a class are the compounds behind the grapefruit effect. This establishes chemical plausibility — it does not establish a clinical interaction, and no human study has measured one.
  • What is not documented — no measurement of bergamottin or 6′,7′-dihydroxybergamottin content in Fo Shou, no CYP3A4 inhibition assay for the herb, and no human pharmacokinetic interaction trial. Any statement that Fo Shou “acts like grapefruit” goes beyond the evidence.
  • Species-level context — furanocoumarin content differs sharply across citrus: comparative work found grapefruit the strongest CYP inhibitor among twelve citrus extracts, with satsuma mandarin relatively weak, and inhibition tracked naringin, bergamottin and 6′,7′-dihydroxybergamottin content. Lime and sour orange peel can exceed grapefruit in bergamottin. Separately, standardized bitter orange (Citrus aurantium) extracts — the species behind Zhi Shi and Zhi Ke — were found to contain under 20 µg/g total furanocoumarins, too little to be expected to affect drug metabolism at usual doses. This is exactly why species-specific data matters rather than a blanket citrus warning.
  • Practical position — patients on narrow-therapeutic-index CYP3A4 substrates (for example certain immunosuppressants, some statins, some calcium-channel blockers or antiarrhythmics) should discuss any citrus-derived herb with their prescriber. This is precautionary and based on constituent class, not on a demonstrated interaction for this herb.

  Sources: PMID 40490235, DOI 10.1016/j.jep.2025.120118 (furanocoumarins absorbed after Citri Sarcodactylis Fructus dosing); PMID 18451520, DOI 10.1248/bpb.31.925 (comparative CYP inhibition across 12 citrus extracts); PMID 28749005, DOI 10.1111/jcpt.12595 (bergamottin/DHB quantitation across citrus flesh and peel); PMID 25026202, DOI 10.3109/19390211.2014.937047 (furanocoumarin content of bitter orange extracts); PMID 17301733 (naringin and OATP1A2); PMID 23297175, DOI 10.1136/bmj.f1 (grapefruit–drug interaction mechanisms). Reference context only — not medical advice.

Western / Biomedical Research

Chinese Herb Clinical Studies & Research

Provided as research context — a summary of published biomedical study, not a therapeutic or medical claim.

• Is there modern research on Fo Shou (Citrus medica var. sarcodactylis)?

  Yes — a substantial and growing preclinical literature, concentrated on the two traditional uses (cough/phlegm and gastrointestinal motility), plus chemistry, essential oil and polysaccharide work. There are no human clinical trials of the herb. Its characterized constituents fall into three groups: volatile oil (dominating the aroma), coumarins and flavonoids (including limettin/5,7-dimethoxycoumarin, scoparone, bergapten, polymethoxyflavones, limonin and nomilin), and water-soluble polysaccharides.

  • Expectorant and antitussive (animal, mechanism) — spectrum–effect studies identified a 70% ethanol fraction as the active expectorant and antitussive fraction, screening out scoparone, 5,6,7-trimethoxycoumarin, 5,7-dimethoxycoumarin, limonin, nomilin and a trimethoxyflavone as candidate actives, with AKT/EGFR implicated. These correspond to the traditional “transforms phlegm, stops cough” indication but are rodent models only.
  • Gastrointestinal motility (animal) — separate spectrum–effect/network-pharmacology and metabonomic studies report gastrointestinal motility-promoting effects and a protective effect in gastrointestinal motility disorder models, aligning with the traditional middle-burner indication.
  • Anti-inflammatory (cell/animal) — the essential oil and its constituents blocked JNK, ERK and NF-κB signalling in LPS-activated macrophages; extracts reduced inflammation in RAW264.7 cells via NF-κB and MAPK; and an extract was reported to lessen LPS-induced acute lung injury in mice.
  • Polysaccharides (cell/animal) — a galactorhamnan and other water-soluble polysaccharides have been isolated and structurally characterized, with reported immunomodulatory, anti-inflammatory and hypolipidemic activity; a 2024 review surveys the whole polysaccharide literature.
  • Metabolic (animal) — finger citron and its characteristic component limettin reduced diet-induced obesity in mice via gut-microbiota and steroid-hormone pathways.
  • Chemistry and processing — a 2026 review covers extraction and composition of the volatile oil and reports antidepressant, anti-anxiety and sleep-related activity in the preclinical literature; other work maps tissue-specific phenolics and the effect of steam processing on aroma and the herb’s “drying” character.

  All of the above is laboratory or animal work. None of it demonstrates clinical efficacy in people, and none of it should be read as a treatment claim.

  Sources: PMID 40490235, DOI 10.1016/j.jep.2025.120118 (expectorant material basis); PMID 38211391, DOI 10.1016/j.jchromb.2023.123987 (antitussive material basis); PMID 39393559, DOI 10.1016/j.jep.2024.118926 and PMID 41240413 (gastrointestinal motility); PMID 23541436, DOI 10.1016/j.fct.2013.03.017 (essential oil, anti-inflammatory); PMID 41750880, PMC 12939456 (extract, NF-κB/MAPK); PMID 40901654, PMC 12400161 (acute lung injury model); PMID 35757248, PMC 9225144 (galactorhamnan polysaccharide); PMID 41623966, PMC 12853050 (polysaccharide, hypolipidemic); PMID 39427793, DOI 10.1016/j.ijbiomac.2024.136640 (polysaccharide review); PMID 41849251, DOI 10.1021/acs.jafc.5c15347 (limettin, diet-induced obesity); PMID 42353588, PMC 13298285 (volatile oil review); PMID 42193186, PMC 13203400 (tissue-specific phenolics); PMID 41674693, PMC 12887779 and PMID 42011609 (steam processing). Research context, not a therapeutic claim.

Chinese Herb Notes

• How is Fo Shou different from Xiang Yuan, Chen Pi and the other citrus herbs?

  Fo Shou and Xiang Yuan come from the same species — the citron, Citrus medica — but Fo Shou is specifically the fingered variety (Citrus medica L. var. sarcodactylis), whose fruit splits into finger-like segments and is used whole in slices, while Xiang Yuan (香櫞, Fructus Citri) is the ordinary rounded citron fruit. They are close relatives with overlapping actions — both regulate qi, harmonize the middle, and transform phlegm — and the two are frequently discussed as a pair. The practical distinction usually drawn is that Fo Shou is the more fragrant and better tolerated of the two, with a slightly stronger reach into the Liver and Spleen, while Xiang Yuan is regarded as the plainer middle-burner qi mover. Fo Shou is the only one of the pair held as a separate record here.

  How Fo Shou sits within the wider citrus family:

  • Fo Shou — finger citron fruit (Citrus medica var. sarcodactylis). The whole sliced fruit; spicy, bitter, slightly warm; Liver, Lung, Stomach, Spleen. Liver-qi-spreading and phlegm-transforming — the citrus herb that most clearly bridges the two.
  • Chen Pi — aged tangerine peel (Pericarpium Citri Reticulatae, from Citrus reticulata). The whole ripe peel, dried and aged; the everyday middle-burner qi regulator and damp-transformer. Fo Shou is more Liver-directed; Chen Pi is more squarely Spleen/Stomach.
  • Ju Hong — the outermost red layer of that same tangerine peel (Exocarpium Citri Rubrum). More drying and more aromatic than Chen Pi, and aimed at cough with copious sputum. Where Fo Shou is gentle, Ju Hong is the drier, more phlegm-focused option.
  • Qing Pi — green (unripe) tangerine peel (Pericarpium Citri Reticulatae Viride). Harsher and more descending, targeting Liver/Gallbladder qi stagnation and hard accumulations — a much stronger, more breaking herb than Fo Shou.
  • Zhi Shi and Zhi Ke — bitter orange (Citrus aurantium), immature fruit and mature fruit respectively. These are a different species from both the citron and the tangerine, and their action is downward-driving rather than fragrant-spreading.
  • Ju He — tangerine seed (Semen Citri Reticulatae). Yet another part of Citrus reticulata, used for a quite different indication (Liver-channel stagnation and swelling in the lower body).

  Combinations: Fo Shou is commonly paired with other fragrant qi-regulators — with Xiang Fu and Chai Hu where Liver-qi constraint dominates, or with Chen Pi and Mu Xiang for epigastric fullness and poor appetite — and with phlegm-transforming herbs when the cough side of its action is wanted. It is not a chief herb in the classical formulas held on this site; it appears more often as a modification and in modern patent and food-grade preparations. (Traditional formula context, not treatment advice.)

  Identity note for review: the pharmaceutical Latin recorded here is “Fructus Citri Sacrodactylis.” The spelling used throughout the botanical and research literature is sarcodactylis (Citri Sarcodactylis Fructus). We believe these denote the same herb; the identity field is left unchanged pending owner confirmation.

  Source: Sacred Lotus sources & references (citrus herb identities, nature/flavour, channels and part-of-plant as held on file); cross-referenced against multiple online sources and materia medica consensus (Bensky; Chen & Chen).