Herb

Hai Zao

Sargassum | 海藻

Also known as:

Herba sargassi

Hai Zao

Product appearance may vary from images shown

Properties

Phlegm-transforming herbs (化痰药) · Cold

Traditionally supports*

Thyroid Health Lymphatic Health Nodule and Mass Support Fluid Retention and Edema

Parts Used

Whole plant / Aerial parts (全草 quán cǎo)

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.

Select Product Type

Select Supplier

Select Size

Quantity

$23.00 ($0.40/g)
For shipments to: United States Change
Standard Shipping (3-5 business days): $4.99
Express Shipping (1-2 business days): $9.99
Free shipping on orders over $75

About This Herb

Traditional Chinese Medicine background and properties

Herb Description

Hai Zao is a type of seaweed used in Chinese medicine primarily to soften and dissolve lumps, nodules, and swellings. It is best known for addressing thyroid enlargement (goiter), swollen lymph nodes, and testicular swelling. It also helps the body expel excess fluids, making it useful for certain types of edema.

Herb Category

Phlegm-transforming herbs (化痰药) Herbs that cool and transform Phlegm-Heat (清化热痰药)

Main Actions

  • Dissipates Nodules and Softens Hardness
  • Dissolves Phlegm
  • Promotes Urination and Reduces Edema

How These Actions Work

'Softens hardness and dissipates nodules' (软坚散结 ruǎn jiān sàn jié) means Hai Zao can help break down hard lumps, masses, and swellings in the body. Its salty taste has a natural softening effect on hardened tissue, while its cold nature helps clear the Heat that often accompanies chronic nodules. This is why it has been a go-to herb for centuries for conditions like goiter (thyroid enlargement), swollen lymph nodes (scrofula), and testicular swelling. It enters the Liver and Kidney channels, which govern the areas where these conditions commonly develop.

'Dissolves Phlegm' (消痰 xiāo tán) refers to Hai Zao's ability to resolve pathological Phlegm, which in TCM does not just mean mucus in the throat. Phlegm can congeal under the skin or in the organs to form lumps, cysts, and masses. Hai Zao's bitter taste helps dry and disperse this congealed Phlegm, while its salty quality breaks it down. This action works hand-in-hand with its nodule-dissolving effect.

'Promotes urination and reduces edema' (利水消肿 lì shuǐ xiāo zhǒng) means Hai Zao helps the body move and expel excess water. Though this is considered a secondary action (and Hai Zao is usually combined with stronger diuretic herbs like Fu Ling or Ze Xie for this purpose), it contributes to the overall strategy of clearing fluid stagnation from the body.

Patterns Addressed

In TCM, symptoms cluster into recognizable patterns of disharmony that reveal what's out of balance in the body. Hai Zao is traditionally associated with these specific patterns.

The following describes this herb's classification within Traditional Chinese Medicine theory and is provided for educational purposes only.

Why Hai Zao addresses this pattern

Hai Zao's cold nature directly clears the Heat component of Phlegm-Fire, while its bitter taste dries Phlegm and its salty taste softens the hardened masses that Phlegm-Fire produces when it congeals. By entering the Liver and Stomach channels, Hai Zao targets the areas where Phlegm-Fire most commonly manifests as visible nodules: the neck (goiter, scrofula) and the lower abdomen (testicular swelling). This makes it a primary herb for dissolving the hard, stubborn accumulations that are the hallmark of this pattern.

A practitioner would look for one or more of these signs

Goiter

Goiter or thyroid enlargement from Phlegm-Fire congealing in the neck

Reactive Lymphadenopathy

Swollen, hard lymph nodes (scrofula)

Testicular Pain

Testicular swelling and pain from Phlegm and Qi accumulation

TCM Properties

Temperature

Cold

Taste

Bitter (苦 kǔ), Salty (咸 xián)

Channels Entered
Liver Stomach Kidneys
Parts Used

Whole plant / Aerial parts (全草 quán cǎo)

This is partial information on the herb's TCM properties. More detailed information is available on the herb's dedicated page

Product Details

Manufacturing, supplier, and product specifications

Product Type

Granules

Quantity Description

Loading quantity information...

Concentration Ratio

Loading concentration information...

Fabrication Method

Loading fabrication information...

Supplier Certifications

Loading certifications information...

Botanical & Sourcing

Quality Indicators

Good quality Hai Zao should be dark blackish-brown in color with minimal white salt encrustation (盐霜). The branches should be young and tender, without sand, stones, or other debris mixed in. When moistened, the herb should become soft, fleshy, and slippery (粘滑). The smell should be distinctly fishy (腥), and the taste should be mildly salty. For large-leaf Hai Zao (大叶海藻): look for intact pieces 30-60 cm long with visible lance-shaped leaves, spherical black-brown air bladders, and short spiny protrusions on the main axis. For small-leaf Hai Zao (小叶海藻): pieces are smaller (15-40 cm), with strip-shaped or narrow spoon-shaped leaves, spindle-shaped air bladders on longer stalks, and no spiny protrusions. The texture should be somewhat harder than the large-leaf variety. Per Pharmacopoeia standards: moisture content should not exceed 19.0%, and alcohol-soluble extractives should be no less than 6.5%.

Primary Growing Regions

Large-leaf Hai Zao (Sargassum pallidum): primarily distributed along the Yellow Sea and Bohai Sea coasts of Liaoning and Shandong provinces. Small-leaf Hai Zao (Sargassum fusiforme): more widely distributed along the coasts of Liaoning, Shandong, Fujian, Zhejiang, and Guangdong provinces. Shandong and Fujian are considered the primary producing regions. The best medicinal quality traditionally comes from the Shandong coastal region.

Harvesting Season

Summer and autumn, harvested by gathering or cutting from the sea

Supplier Information

Treasure of the East

Loading supplier information...

Loading supplier attributes...

Miscellaneous Info

No additional information available

Usage & Safety

How to use this herb and important safety information

Important Medical Disclaimer

The information provided here is for educational purposes only and is not intended as medical advice or to replace consultation with a qualified healthcare professional. This herb is a dietary supplement and has not been evaluated by the FDA. It is not intended to diagnose, treat, cure, or prevent any disease.

Always consult with a qualified healthcare provider, particularly if you are pregnant, nursing, have a medical condition, or are taking other medications. Discontinue use and consult your healthcare provider if you experience any adverse reactions.

Recommended Dosage

Loading dosage information...

Instructions for safe storage and consumption

Loading storage and consumption information...

Traditional Dosage Reference

Standard

6-12g

Maximum

Up to 15g in some clinical applications for goiter or stubborn nodules, under practitioner supervision

Notes

The standard decoction dose is 6-12g. For treating goiter (瘿瘤) and thyroid nodules, the full dose of 10-12g is commonly used. For milder conditions such as edema or phlegm accumulation, lower doses of 6-9g may suffice. Hai Zao can also be taken as wine-soaked preparation (酒渍), ground into powder, or formed into pills. When using Hai Zao for its iodine content in thyroid disorders, practitioners should be aware that it may temporarily suppress hyperthyroid symptoms but cannot treat the underlying condition long-term. In patients with hyperthyroidism, iodine-rich herbs like Hai Zao should generally be avoided.

Processing Methods

Processing method

The raw seaweed is soaked briefly in fresh water to remove excess salt, then drained, cut into segments, and sun-dried.

How it changes properties

This standard preparation removes the harsh saltiness and any sand or impurities from the marine environment. The core properties (bitter, salty, cold) and actions remain largely unchanged, but the reduced salt content makes it gentler on the Stomach and easier to combine with other herbs in decoction.

When to use this form

This is the standard form used in virtually all clinical applications. Raw, unwashed Hai Zao is rarely used directly due to its heavy salt content and marine impurities.

Toxicity Classification

Non-toxic

The Yao Xing Lun and Ben Cao Hui Yan both describe Hai Zao as having "slight toxicity" (有小毒), though the current Chinese Pharmacopoeia does not classify it as toxic. The main safety concern relates to its high iodine content: excessive or prolonged intake can disrupt thyroid function, particularly in individuals with pre-existing thyroid conditions. Alginate sodium (藻胶酸钠), a component of Hai Zao, has shown toxicity in animal studies when injected intraperitoneally in mice, but oral administration at standard dosages is generally safe. The Ben Cao Bian Du warns that overuse of salty-cold substances like Hai Zao can cause blood stagnation and decline of vitality over time.

Contraindications

Avoid

Incompatible with Gan Cao (Glycyrrhiza/Licorice) according to the classical Eighteen Incompatibilities (十八反). Combined use may reduce therapeutic efficacy or increase toxicity. Avoid concurrent use unless under expert supervision.

Caution

Spleen and Stomach deficiency-cold (脾胃虚寒) with internal dampness. Hai Zao is bitter, salty, and cold in nature, which can further damage already weakened digestive function.

Caution

Hyperthyroidism (甲亢). Hai Zao is rich in iodine, which can worsen hyperthyroid conditions. People with overactive thyroid should avoid this herb.

Caution

Pregnancy. The cold nature and blood-moving properties of Hai Zao may be unsuitable during pregnancy. Use with caution or avoid.

Avoid

Iodine allergy or sensitivity. As a marine algae rich in iodine, individuals with known iodine allergies should not use Hai Zao.

Classical Incompatibilities

Hai Zao is one of the four herbs listed as incompatible with Gan Cao (甘草, Licorice) in the Eighteen Incompatibilities (十八反): "藻戟遂芫俱战草" — Hai Zao (海藻), Da Ji (大戟), Gan Sui (甘遂), and Yuan Hua (芫花) all oppose Gan Cao. This prohibition originates from the Shen Nong Ben Cao Jing and was formalized in the Eighteen Incompatibilities verse recorded in Zhang Congzheng's Ru Men Shi Qin (《儒门事亲》). Combined use is traditionally held to reduce efficacy or increase toxicity. However, this remains debated: some classical formulas (such as Hai Zao Yu Hu Tang) deliberately combine both herbs, and modern animal studies have shown mixed results regarding actual toxicity.

Special Populations

Pregnancy

Use with caution during pregnancy. Hai Zao is cold in nature with properties that promote water metabolism and disperse accumulations. While not explicitly listed as a major pregnancy-prohibited herb, its cold and dispersing nature could potentially disturb fetal stability. Its high iodine content is also a concern, as excessive iodine intake during pregnancy can affect fetal thyroid development. Classical sources such as the Ben Cao Hui Yan note its "slight toxicity." Pregnant women should avoid this herb unless specifically prescribed by an experienced practitioner.

Breastfeeding

Safety data specific to breastfeeding is limited. The high iodine content of Hai Zao is the primary concern, as iodine passes readily into breast milk. Excessive maternal iodine intake can affect the infant's thyroid function. Its cold nature may also theoretically affect milk quality for mothers with weak digestion. Use only under practitioner guidance during breastfeeding, and keep dosages conservative if prescribed.

Pediatric Use

No specific pediatric dosage guidelines are established in classical or modern TCM texts for Hai Zao. Due to its cold nature and iodine content, use in children should be conservative and only under practitioner supervision. Dosages should generally be reduced to one-third to one-half of the adult dose depending on the child's age and weight. Not recommended for young children with weak digestion or Spleen-Stomach deficiency.

Drug Interactions

Thyroid medications: Hai Zao is rich in iodine and may interfere with thyroid hormone medications (levothyroxine) or anti-thyroid drugs (methimazole, propylthiouracil). Its iodine content can alter thyroid hormone levels, potentially counteracting the effects of these medications.

Anticoagulant/antiplatelet drugs: Early research suggested that degraded alginate compounds from seaweed may have mild anticoagulant properties. Concurrent use with warfarin, heparin, or antiplatelet medications should be monitored, though clinical significance at standard herbal doses is unclear.

Antihypertensive drugs: Animal studies show that larger doses of Hai Zao can lower blood pressure. Concurrent use with antihypertensive medications may have an additive hypotensive effect.

Lithium: As with other iodine-rich substances, Hai Zao may theoretically interact with lithium, which affects thyroid function and iodine metabolism.

Dietary Advice

During treatment with Hai Zao, avoid foods and herbs that contain Gan Cao (Licorice), including herbal teas and confections that commonly include licorice. Reduce intake of excessively cold or raw foods to protect Spleen and Stomach function, as Hai Zao is already cold in nature. People with hypothyroidism being treated with Hai Zao for its iodine content should maintain a balanced diet and not consume excessive amounts of other iodine-rich foods (such as kelp or iodized salt) simultaneously. Those with hyperthyroid conditions should avoid Hai Zao and other high-iodine foods entirely.

Cautions & Warnings

Although this herb is typically safe for most individuals, it may cause side effects in some people. Pregnant women, nursing mothers, postpartum women, and those with liver disease should use the formula with caution.

As with any Chinese herbal remedy, it is advisable to seek guidance from a qualified TCM practitioner before beginning treatment.