Guan Zhong (Wood Fern or Dryopteris)

What Is Guan Zhong

Guan Zhong commonly known as Wood Fern, Male Fern, Buckler Fern, or Dryopteris is the rhizome of Dryopteris crassirhizoma, which is a perennial fern belonging to the Dryopteridaceae family. It is one of the earliest medicines discovered and applied in traditional Chinese herbal medicine, which first appeared in <Shennong Ben Cao Jing> in the late Western Han Dynasty (about 100 BC).

There are about 400 species of Dryopteris, which are distributed in Asia, Europe, America, and the Pacific islands. Most of these species grow in East Asia.

Dryopteris crassirhizoma is cold and drought tolerant, and it likes a warm, humid, semi-shady environment. They grow well in deep, well-drained, loose, fertile, slightly acidic, and neutral sandy soils rich in organic matter. They are distributed in China, Japan, North Korea, Vietnam, and Thailand.

Dryopteris crassirhizoma

In the autumn of each year, people gather the rhizomes of Dryopteris crassirhizoma, wash them with water, remove their impurities and fibrous roots, cut them into thick pieces, dry them in the sun, and make them into Chinese herbal medicines.

Guan Zhong contains aspidin, albaspidin, filicic acid, flavaspidic acid, dryocrassin, isoquercitrin, astragalin, catechinic acid, daidzein, triterpenoids, steroids, caffeic acid, glycosides, and volatile oils.

Generally, Guan Zhong with yellowish-brown or black-brown outer epidermis and light brown or reddish-brown cross-section is preferred.

According to <Shennong Ben Cao Jing>, the medicinal property of Guan Zhong is slightly cold, with slight toxicity and bitter taste. It has a certain therapeutic effect on the pathological changes of the liver and spleen meridians.

In traditional Chinese medicine, Guan Zhong is often used to clear heat and remove toxins, cool blood and stop bleeding, kill worms, treat wind-heat, influenza, upper respiratory tract infection, ascariasis, acute orchitis, upper gastrointestinal bleeding, drug-induced hepatitis, and gynecological bleeding.

There are about 50 kinds of traditional Chinese medicine prescriptions containing Guan Zhong, such as Lianhua Qingwen capsule, Fu Fang Qing Dai Wan, and Da Huo Luo Dan.


  • Anti-oxidation, anti-malaria, and anti-tumor.
  • Inhibiting leukemia cells and exciting the uterus.
  • Relieving fever, headache, nasal obstruction, and sore throat caused by wind-heat.
  • Clearing heat and eliminating maculae caused by warm toxins.
  • Cooling blood and relieving hematemesis, epistaxis, and hematochezia caused by blood heat.
  • Treating leukorrheal diseases, menorrhagia, postpartum lochia, and metrorrhagia.
  • Inhibiting influenza virus, parainfluenza virus, avian influenza virus, respiratory syncytial virus, adenovirus, poliovirus, and Japanese encephalitis virus.
  • Inhibiting dysentery bacilli, typhoid bacilli, Escherichia coli, Proteus, Pseudomonas aeruginosa, Bacillus subtilis, Staphylococcus aureus, and some skin fungi.
  • It contains filicic acid and flavaspidic acid, which can expel a variety of intestinal parasites, such as tapeworms, hookworms, pinworms, roundworms.
  • The topical application of it can treat burns and scalds, with hemostasis, analgesic, anti-inflammatory effects.


  • It can be used in combination with Huang Lian (Rhizoma Coptidis) to treat epistaxis caused by blood heat.
  • It can be used in combination with Sang Ye (Mulberry Leaf) and Jin Yin Hua (Flos Lonicerae) to treat fever, headache, nasal obstruction, and sore throat caused by wind-heat.
  • It can be used in combination with Yu Mi Xu (Corn Silk) and Bai Mao Cen (Rhizoma Imperatae) to treat chyluria.
  • It can be used in combination with Chuan Shan Jia (Squama Manitis), Zhen Zhu (Pearl), and Bing Pian (Borneol) to treat newborn omphalitis.
  • It can be used in combination with Bi Xie (Rhizoma Dioscoreae Hypoglaucae), Dang Shen (Radix Codonopsis), and Ji Xue Teng (Caulis Spatholobi) to treat chronic lead poisoning.

Side Effects

Guan Zhong is poisonous, and some countries stipulate that it can only be used for external use.

Taking it in large doses may cause headache, dizziness, abdominal pain, diarrhea, dyspnea, yellow vision, or transient blindness.

In severe cases, it may cause delirium, coma, jaundice, renal impairment, paroxysmal convulsions, respiratory failure, permanent blindness, or death.

Precautions and Warnings

  • The dosage of Guan Zhong should be controlled between 4.5-9g.
  • It can be made into decoctions or ground into powder for external use.
  • People who are allergic to Guan Zhong should not take it.
  • The unprocessed Guan Zhong is recommended for clearing heat and removing toxins, and the carbonized Guan Zhong is recommended for stopping bleeding.
  • Fat can promote the body’s absorption of aspidin, so it is not recommended to eat greasy foods during medication.
  • It should not be used to clear internal heat caused by Yin deficiency.
  • Pregnant and lactating women should not take it.
  • Children should take it under the guidance of doctors.
  • People with deficiency-cold in the spleen and stomach should not take it.
  • People with weak constitutions, liver and kidney dysfunction or peptic ulcers should not take it.

Treatment for poisoning

If the patient takes it and causes adverse reactions, please seek medical attention in time.

The following treatment methods for poisoning are for reference only, please refer to the doctor’s diagnosis.

  • Taking a general antidote to alleviate poisoning.
  • Infusion is recommended to supplement body fluids and electrolytes lost due to vomiting or diarrhea.
  • Taking salt laxatives to promote the excretion of poisons from the intestine. It is not recommended to use oily laxatives such as castor oil.
  • Intravenous barbiturates can relieve convulsions during medication.
  • When breathing difficulties occur during medication, it is recommended to supply oxygen, use respiratory stimulants or artificial respiration.