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Limited evidenceEye health

Cassia Seed (Jue Ming Zi)

Roasted Cassia obtusifolia seeds, brewed as a tea in Chinese medicine for eye strain and constipation. The name literally means 'brighten the eyes', but the eye claim has never been tested clinically, and the seeds carry a real hepatotoxicity concern.

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What the science says

  • Eye strain and vision Limited evidence

    A comprehensive review of Cassiae Semen documents its principal traditional indication as clearing the liver and brightening the eyes, but reports no controlled clinical trials for visual or ocular endpoints. The supporting pharmacology is limited to antioxidant and anti-inflammatory activity in laboratory systems.

  • Laxative effect Limited evidence

    The same review describes anthraquinone constituents with documented laxative activity, consistent with the seed's traditional use for constipation. Human dosing and efficacy have not been established in randomised trials.

  • Hepatotoxicity risk Limited evidence

    The review's toxicity section flags anthraquinone-related liver toxicity as the main safety concern with Cassiae Semen, particularly with prolonged or high-dose use. This is the best-characterised risk of the herb and argues against daily long-term consumption.

Dosage & safety

Studied doseNo clinically studied dose. Traditional decoction use is 9–15 g of roasted seeds per day, usually short term; the roasted form is standard and raw seeds are considered harsher.
SafetyAnthraquinones in cassia seed carry a documented hepatotoxicity signal and, like other anthraquinone laxatives, should not be used continuously — avoid long-term daily use and avoid entirely with existing liver disease. Diarrhoea and abdominal cramping are common at higher intakes. Avoid in pregnancy and breastfeeding, in children, and alongside other laxatives or hepatotoxic drugs. It may lower blood pressure, so monitor if taking antihypertensives.

How to take it

TimingShort courses only - anthraquinone laxatives are not for continuous daily use, and traditional practice treats this as a temporary remedy.
With food?With or without food; higher intakes cause cramping and diarrhoea either way.
Worth knowingUse the roasted seeds, which is the standard preparation - raw seeds are considered harsher and more purgative.

Interactions

With medications

  • digoxin, and diuretics such as furosemide or thiazides

    Like other anthraquinone laxatives, prolonged use causes potassium loss, which increases digoxin toxicity and compounds diuretic-induced hypokalaemia. do not use it regularly alongside these drugs

  • antihypertensive medication

    Cassia seed may lower blood pressure, adding to the drug's effect. monitor your blood pressure when starting or stopping

  • any oral medication taken at the same time

    The laxative effect speeds intestinal transit and can reduce absorption of drugs taken alongside it. separate other oral medicines by at least 2 hours

  • methotrexate, isoniazid and other drugs that stress the liver

    Anthraquinones in cassia seed carry their own documented hepatotoxicity signal. avoid the combination, and avoid cassia seed entirely with existing liver disease

With other supplements

  • senna, cascara, aloe latex and other anthraquinone laxative herbs

    Additive purgative effect, potassium loss and cumulative liver risk. do not stack anthraquinone herbs

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does cassia seed tea improve eyesight?

No clinical trial has tested cassia seed (jue ming zi) for eye strain or vision, despite its name meaning 'brighten the eyes'. The evidence is limited to traditional use and lab studies.

Is cassia seed tea safe to drink daily?

No. Cassia seed contains anthraquinones with a documented liver toxicity signal, so avoid long-term daily use and avoid it entirely with liver disease, in pregnancy, while breastfeeding and in children.

Does cassia seed work as a laxative?

Cassia seed contains anthraquinones with documented laxative activity, matching its traditional use for constipation, but dose and efficacy have not been established in randomised trials. Use short courses only and do not stack it with senna, cascara or other laxatives.

Can cassia seed interact with medication?

Yes. Prolonged cassia seed use can cause potassium loss that raises digoxin toxicity and adds to diuretic effects, it may lower blood pressure, and its laxative action can reduce absorption of other oral medicines, so separate them by at least 2 hours.

Scientific references

Related in Eye health

Herbal medicines: what the evidence says (335)