Xing Ren (杏仁) — Bitter Apricot Kernel | TCM Herb for Cough & Constipation

At a Glance

Herb: Xing Ren
Chinese name: 杏仁 (Xìng Rén)
Latin name: Semen Armeniacae Amarum
Nature: Warm
Taste: Bitter
Meridian: Lung / Large Intestine
Category: Herbs that Relieve Cough and Wheezing
Introduction: Xing Ren (杏仁, Semen Armeniacae Amarum) is the dried ripe seed of Prunus armeniaca L. var. ansu Maxim. or related species. Commonly called bitter apricot kernel, it is one of the most widely used herbs in the Chinese materia medica for respiratory conditions. The bitter flavour directs it to descend Lung qi, while its oily nature moistens the Intestines. First documented in the Shennong Bencao Jing as a middle-grade herb, Xing Ren has appeared in nearly every major respiratory formula across two millennia of clinical practice — from Ma Xing Shi Gan Tang to Sang Xing Tang to Xing Su San. Note: bitter apricot kernel (Ku Xing Ren) is distinguished from sweet apricot kernel (Tian Xing Ren, Semen Armeniacae Dulce) — the bitter form is standard for medicinal use; the sweet form is a milder food-grade variant.

Descends Lung qi and relieves cough and wheezing: The primary action. Suitable for cough and wheezing from virtually any aetiology — cold, heat, dryness, or phlegm — depending on combination. 2. Moistens the Intestines and unblocks the bowels: The fatty oil content lubricates the Large Intestine; used for constipation due to fluid deficiency or qi stagnation. 3. Disperses Lung qi: The mildly acrid component (from amygdalin hydrolysis) has a dispersing quality that supports opening of the Lung orifices.

Xing Ren is clinically indispensable for the full spectrum of cough and wheezing patterns. For wind-cold cough it pairs with Ma Huang; for wind-heat with Sang Ye and Ju Hua (Sang Ju Yin); for Lung dryness with Bei Sha Shen and Mai Dong (Sha Shen Mai Dong Tang); for Lung heat with Shi Gao and Ma Huang (Ma Xing Shi Gan Tang). For constipation due to fluid deficiency it is combined with Huo Ma Ren and Bai Shao in Ma Zi Ren Wan. Its versatility across exterior and interior, hot and cold patterns makes it one of the highest-frequency herbs in classical formulation.

Toxic in overdose: HCN released from amygdalin can cause cyanide poisoning — symptoms include dizziness, nausea, rapid heartbeat, and in severe cases respiratory failure. Standard therapeutic dose: 5–10 g. Maximum 10 g. Do not use raw in high doses. Contraindicated in infants under 3 years (higher sensitivity to cyanide). Use with caution in Lung yin deficiency with dry cough without phlegm accumulation. Avoid raw seeds without processing.

Ma Xing Shi Gan Tang (麻杏石甘汤): Ma Huang, Xing Ren, Shi Gao, Zhi Gan Cao.
Sang Ju Yin (桑菊饮): Sang Ye, Ju Hua, Xing Ren, Lian Qiao, Bo He, Jie Geng, Lu Gen, Gan Cao.
Ma Zi Ren Wan (麻子仁丸): Huo Ma Ren, Xing Ren, Bai Shao, Zhi Shi, Da Huang, Hou Po.
Xing Su San (杏苏散): Xing Ren, Su Ye, Ban Xia, Fu Ling, Chen Pi, Qian Hu, Jie Geng, Zhi Ke, Gan Cao, Sheng Jiang, Da Zao.

Xing Ren + Ma Huang + Shi Gao + Gan Cao (Ma Xing Shi Gan Tang): Lung heat wheezing with fever. Source: Shang Han Lun (伤寒论).
Xing Ren + Sang Ye + Ju Hua (Sang Ju Yin): Wind-heat cough with sore throat. Source: Systematic Differentiation of Warm Diseases (温病条辨).
Xing Ren + Bei Sha Shen + Mai Dong (Sha Shen Mai Dong Tang): Lung-Stomach yin deficiency with dry cough. Source: Systematic Differentiation of Warm Diseases (温病条辨).
Xing Ren + Su Ye + Ban Xia (Xing Su San): Wind-cool dryness cough with thin phlegm. Source: Systematic Differentiation of Warm Diseases (温病条辨).
Xing Ren + Huo Ma Ren + Bai Shao (Ma Zi Ren Wan): Constipation from Spleen fluid deficiency. Source: Shang Han Lun (伤寒论).

HCN released in small quantities from amygdalin mildly
- Antitussive and antiasthmatic: inhibits the respiratory centre, reducing cough reflex sensitivity
- Antitussive and antiasthmatic: bronchodilatory effects in animal models
Laxative
- Fatty oil content lubricates intestinal mucosa, facilitating stool passage
Amygdalin and its metabolites
- Anti-inflammatory: show anti-inflammatory activity in vitro and in vivo
Anticancer
- Amygdalin (sold as ‘laetrile’) has been extensively studied but evidence for clinical anticancer efficacy remains inconclusive and controversial
Amygdalin metabolites
- Antihypertensive: show mild blood pressure-lowering effects in animal studies

《神农本草经》(Shennong Bencao Jing, circa 200 CE): ‘杏核仁，味甘，温。主咳逆上气，雷鸣，喉痹，下气，产乳，金创，寒心，奔豚。’ (Apricot kernel: sweet flavour, warm. Governs cough with counterflow ascent of qi, rumbling sounds, throat obstruction. Descends qi, facilitates delivery, treats metal wounds, cold sensation in the heart, and running piglet qi.)
《本草纲目》(Bencao Gangmu, 1596): ‘杏仁能散能降，故解肌散风，降气润燥，消积，治伤损药中用之。’ (Xing Ren can disperse and descend: it resolves the muscles and disperses wind, descends qi and moistens dryness, disperses accumulation — used in formulas for trauma and injury.)
《温病条辨》(Wenbing Tiaobian, 1798): ‘杏仁苦温，苦则下气，温则宣通，为宣肺止咳要药。’ (Xing Ren is bitter and warm: bitterness descends qi, warmth promotes movement — it is the essential herb for diffusing the Lung and stopping cough.)