TCM Herbal Decoctions and Dysphagia: A Common Challenge

Traditional Chinese medicine (TCM) herbal decoctions (湯藥, 煎藥) are widely used in Hong Kong for health maintenance, convalescence, and management of chronic conditions. Many elderly patients — the population most likely to have dysphagia — continue TCM treatment alongside Western medical care.

However, standard herbal decoctions present specific risks for patients with dysphagia:

• Inconsistent liquid consistency: decoctions vary in viscosity depending on the herbs used and cooking duration — some are thin and watery (high aspiration risk), others are thick and viscous
• Herb particle content: improperly strained decoctions may contain fine herb particles, dramatically increasing aspiration risk
• Drug interactions: some commonly used Chinese herbs have documented interactions with Western medications

This guide helps caregivers, TCM practitioners, and families in Hong Kong prepare herbal decoctions more safely for dysphagia patients.

IDDSI Considerations for Herbal Decoctions

IDDSI Level 2 (Mildly Thick) and Level 3 (Liquidised)

Most Western-prescribed IDDSI thickened fluid protocols target Level 2 (mildly thick, e.g., nectar consistency) or Level 3 (liquidised, e.g., honey/mildly thick). For a herbal decoction to be safe for a dysphagia patient:

• It must pass through an IDDSI flow test at the prescribed level
• It must be completely free of herb particles and residue after straining
• It must be served at a consistent, safe temperature (not hot enough to scald, not cold enough to cause vasovagal response — ideally 40–45°C)

How to Adjust Decoction Consistency

To achieve Level 2 (Mildly Thick):

1. Prepare the decoction by standard method and strain through a fine-mesh medical strainer or muslin cloth
2. Add a measured amount of xanthan gum-based thickener (e.g., Nutilis Clear) to the strained, cooled (not hot) decoction
3. Stir vigorously for 30 seconds and allow to stand for 1 minute to reach final consistency
4. Perform IDDSI flow test: pour through a 10ml syringe — at Level 2, outflow in 10 seconds should be 1–4ml

To achieve Level 3 (Liquidised):

1. Strain thoroughly as above
2. Add slightly less thickener — target outflow less than 1ml in 10 seconds on syringe test

Note: xanthan gum thickeners are generally considered acceptable for use with herbal decoctions, but some TCM practitioners may prefer natural thickening methods — concentrating the decoction through longer cooking, or using naturally viscous herbs (see below).

Herbs That Produce Naturally Viscous Decoctions

Certain herbs produce naturally thicker, mucilaginous decoctions that may achieve or approach the target IDDSI level without added commercial thickener:

Lily bulb (百合, Bǎi hé): Produces a slightly viscous decoction with a mild, slightly sweet flavour. Combined with rock sugar and slow cooking, approaches a gentle Level 2 consistency. Commonly used for lung dryness and convalescent care.

Tremella mushroom / Snow fungus (銀耳, Yín ěr): Tremella polysaccharides create a naturally viscous, gel-like decoction when cooked thoroughly. A well-cooked tremella soup strained of all solids can approach IDDSI Level 2–3 depending on concentration. Suitable for lung and skin dryness.

Polygonatum (玉竹, Yù zhú): Produces a moderately viscous decoction. Gentle flavour. Used for Yin deficiency.

Astragalus (黃芪, Huáng qí) long-decoction: Extended cooking (2–3 hours) of astragalus root in water produces a slightly thicker liquid suitable for immune tonification. The polysaccharide content contributes mild viscosity.

Chinese yam (山藥 / 淮山, Huái shān): Starchy — long simmering produces a naturally thick, nourishing broth suitable for digestive weakness in elderly patients.

Tremella and goji berry sweet soup (銀耳杞子糖水): A common Hong Kong dessert decoction that can be prepared to Level 2–3 consistency by straining thoroughly and adjusting concentration. Gentle, palatable, and culturally familiar.

Herbs to Use With Caution for Dysphagia Patients

Thin, Watery Decoctions (High Aspiration Risk Without Thickening)

These herbs typically produce thin, water-like decoctions (IDDSI Level 0–1) that require commercial thickening before serving to dysphagia patients:

• Chrysanthemum tea (菊花茶)
• Herbal teas (涼茶)
• Honeysuckle flower decoction (金銀花)
• Most single-herb teas

These are not unsafe per se, but they must be thickened to the patient’s IDDSI level before administration.

Herbs with Relevant Drug Interactions

Danshen (丹參, red sage root):

• Documented interaction with warfarin — may significantly increase anticoagulant effect and bleeding risk
• Inform the prescribing haematologist or cardiologist if the patient uses danshen; INR monitoring should increase

Ginkgo biloba (銀杏葉):

• Antiplatelet effect — increased bleeding risk with warfarin and aspirin
• Use with caution or avoid in patients on anticoagulants

Licorice root (甘草, Gān cǎo):

• Can cause potassium depletion and sodium retention with prolonged use — relevant for patients on antihypertensives, digoxin, or diuretics
• Most traditional formulas use small amounts — clinical significance is usually low at typical decoction doses

Aconite (附子, Fù zǐ):

• Potentially cardiotoxic alkaloids — must only be used in properly prepared, detoxified forms under a registered TCM practitioner’s supervision
• Never self-prescribe; never for patients on antiarrhythmics

St John’s Wort (貫葉連翹): Though not traditional Cantonese herbal medicine, occasionally used — strongly reduces blood levels of many Western drugs including antiretrovirals, cyclosporin, warfarin, and oral contraceptives through CYP3A4 induction

Practical Preparation Guide for Caregivers

Step-by-Step: Safe Decoction for a Dysphagia Patient

1. Consult a registered TCM practitioner (香港中醫藥管理委員會 — CMCHK) for the herbal formula — do not self-prescribe complex formulas
2. Purchase herbs from a licensed TCM dispensary — ensure herbs are clean and clearly labelled
3. Cook in a clay pot or stainless steel pot — avoid aluminium which may leach with acidic decoctions
4. Strain twice: first through a coarse strainer, then through a fine-mesh medical strainer or clean muslin cloth — remove all solid particles
5. Cool to 40–45°C before adding commercial thickener
6. Add thickener and test consistency using IDDSI syringe test or fork/spoon test per patient’s prescribed level
7. Administer in small sips — do not rush; allow patient to clear swallow between each sip
8. Never leave unattended — supervise all swallowing of herbal decoctions

Coordination Between TCM and Western Medicine

In Hong Kong, TCM and Western medicine co-exist in most elderly patients’ care routines. Best practice:

• Inform both the Western doctor and TCM practitioner of all medications and herbs being taken
• Ask the TCM practitioner to review the herb list for any known interactions with prescribed Western medications
• Some HA hospitals have integrated TCM-Western medicine consultation services — check with the managing specialist team

Herbal decoctions can be an important part of recovery and comfort care for many Hong Kong patients. With correct preparation and consistency testing, most can be adapted to meet IDDSI requirements and administered safely.