The Thickener Dilemma Facing Hong Kong Carers
For family caregivers in Hong Kong, buying a thickener is rarely straightforward. Commercial options at the pharmacy cost several hundred dollars per tin. Cornstarch from the supermarket costs a fraction of that. Online communities debate xanthan gum versus starch — but with little consensus on what works best for home use.
What complicates this further is that different products, even at the same dose, can produce very different consistencies. And a product that performs reliably in cold water may fail completely when added to a hot cup of Chinese tea.
This guide takes a Hong Kong market perspective — comparing what is actually available to local carers, at realistic prices, in practical home conditions.
Three Categories of Thickener in Hong Kong
Category 1: Household Starch (Cornstarch / Tapioca Starch)
Cornstarch (粟粉, from corn) and tapioca starch (生粉, from cassava) are the cheapest and most accessible thickening options. They are sold in every supermarket and are sometimes used in care home kitchens under budget constraints.
How they work: Starch granules absorb water and swell, creating a viscous network. This process is highly temperature-dependent — in hot liquids, starch gelatinises rapidly; as the liquid cools, consistency continues to increase.
Appearance: Liquid turns opaque and slightly cloudy with a starchy feel.
Advantages: Very low cost (HKD $10–30 / 400g); available everywhere. Disadvantages: Consistency changes substantially with temperature and time; difficult to achieve stable, repeatable IDDSI levels; chalky or pasty taste.
Category 2: Modified Starch — Commercial Medical-Grade Thickeners
Modified starch thickeners use refined starch formulations that are more consistent than plain cornstarch. Commercial products typically come with specific dosing guidelines, and some have manufacturer-validated IDDSI data.
Common in Hong Kong: Starch-based thickening powders from large pharmacy chains and medical supply retailers.
How they differ from plain cornstarch:
- Faster and more uniform thickening than household cornstarch
- Some products have manufacturer-verified IDDSI levels
- Still temperature-sensitive; not recommended for hot drinks
Approximate cost: HKD $80–150 / 225–300g
Category 3: Xanthan Gum-Based Commercial Thickeners
Xanthan gum is a natural polysaccharide produced by microbial fermentation of corn starch. It is widely used in the food industry and is the preferred choice in most modern dysphagia care settings.
Hong Kong market examples: Clear-type xanthan gum thickeners (dissolved in liquid, they remain near-transparent — unlike starch, which turns milky).
Core advantages of xanthan gum:
- Shear-thinning (pseudoplastic) behaviour: At rest, xanthan-thickened liquid holds its IDDSI level well. Under the shear force of swallowing, viscosity momentarily decreases — making the bolus easier to move through the pharynx. This aligns with the physiological needs of dysphagia patients.
- Temperature-stable: Maintains consistent thickness in both hot and cold liquids.
- High IDDSI flow-test repeatability: Results from the syringe flow test are consistent across different time points after preparation.
Approximate cost: HKD $150–300 / 125–175g (smaller cans but higher concentration — less product needed per serving)
Full Comparison Table
| Criterion | Household Cornstarch | Medical-Grade Starch | Xanthan Gum-Based |
|---|---|---|---|
| Availability in HK | All supermarkets | Major pharmacies, some online | Large pharmacies, medical supply stores, online |
| Cost per pack | HKD $10–30 | HKD $80–150 | HKD $150–300 |
| Cost per serving | Low (but higher dose needed) | Moderate | Moderate to slightly higher (lower dose needed) |
| Hot drink stability | Poor (highly variable) | Fair | Excellent (not temperature-affected) |
| Cold (refrigerated) stability | Poor (continues to thicken) | Fair | Excellent (minimal change) |
| Stability at 30 min room temp | Consistency increases | May increase | Stable |
| Appearance | Cloudy / opaque | Somewhat cloudy | Near-transparent (clear type) |
| Mouthfeel | Chalky / pasty | Improved vs. cornstarch | Smooth; swallowing more natural |
| Patient acceptance | Variable (some resistant) | Fair to good | Generally higher |
| IDDSI flow-test consistency | Poor (time-dependent) | Fair | Excellent (highly repeatable) |
| Dissolution speed | Requires stirring + 1–2 min wait | Generally faster | Usually stable within 30–60 sec |
| Suitability for carbonated drinks | Not recommended | Not recommended | Check individual brand instructions |
| Drug interaction risk | No known issues | No known issues | Low; isolated reports with some antibiotics — consult pharmacist |
| Suitability for premature infants | Caution — seek medical advice | Check individual product | Not recommended (some brands explicitly state this) |
IDDSI Flow Test: How the Three Categories Perform
IDDSI recommends the Syringe Flow Test to verify drink consistency. Test method:
- Fill a 10 ml syringe (needle removed) with the prepared drink
- Cover the tip with one finger for 10 seconds to allow the liquid to settle
- Release the finger and allow the liquid to flow freely for exactly 10 seconds
- Read the volume remaining in the syringe (in ml)
Target residual volumes by IDDSI level:
| IDDSI Level | Name | Residual Volume After 10 Seconds |
|---|---|---|
| Level 0 | Thin | 1 ml or less |
| Level 1 | Slightly Thick | 1–4 ml |
| Level 2 | Mildly Thick | 4–8 ml |
| Level 3 | Moderately Thick | 8–10 ml (flows slowly) |
| Level 4 | Extremely Thick | 10 ml (does not flow at all) |
How each thickener type performs on this test:
Household cornstarch: Results vary significantly with time — a sample tested 2 minutes after preparation may read Level 2, while the same sample tested 15 minutes later may read Level 3. Consistent dosing requires strict timing, which is difficult to maintain in practice.
Medical-grade starch: More consistent than plain cornstarch, but still affected by temperature and time. Testing should be done within a specified window after preparation (check the product instructions).
Xanthan gum-based: Highest repeatability. Test results at 1 minute and 15 minutes after preparation are typically within the same IDDSI level. Best suited to IDDSI verification in home settings.
Learn how to perform the full IDDSI syringe flow test at home
Where to Buy Thickeners in Hong Kong
Supermarkets (for cornstarch)
- Parknshop, Wellcome, City’super all stock cornstarch (粟粉)
- Choose 100% corn-starch products; avoid mixed starch blends
Chain Pharmacies (for commercial thickeners)
- Mannings and Watsons carry thickening powders at larger branches
- Call ahead to confirm stock — availability varies by location
- Xanthan gum-based options are less commonly stocked than starch-based ones
Medical Supply Stores / Rehabilitation Equipment Companies
- Several Hong Kong medical supply retailers stock a broader range of thickeners than pharmacies
- Some offer monthly subscription or bulk orders — useful for regular users
Online Purchase
- Multiple online medical supply platforms carry both starch and xanthan gum options
- Check whether products ship from local stock (faster) or overseas (longer wait)
- Confirm ingredients carefully before purchasing — product names can be misleading
Frequently Asked Questions
Q: Can I use plain cornstarch instead of a commercial thickener?
A: In an emergency or under very tight budget constraints, cornstarch can serve as a short-term substitute. However, it is not recommended for long-term use. The instability of starch-based thickeners — especially in hot drinks and over time — makes it very difficult to consistently achieve the IDDSI level prescribed by your SLP. This inconsistency is a patient safety risk.
Q: Will a thickener work properly in hot Pu-erh tea or soup?
A: Xanthan gum-based thickeners maintain consistent thickness in hot liquids. Starch-based thickeners (including plain cornstarch) are not reliable in hot drinks — they can gelatinise unevenly and continue thickening as the liquid cools. For all hot drinks, use a xanthan gum-based thickener.
Q: Can patients on medication use xanthan gum thickeners?
A: Some research has noted that xanthan gum may affect the absorption of certain medications (notably some sulphonamide antibiotics). For patients on multiple medications, consult your pharmacist. The interaction risk with commonly prescribed elderly medications (e.g. antihypertensives, hypoglycaemics) is generally considered low, but individual assessment is best.
Q: Do I need to re-verify the IDDSI level when switching brands?
A: Yes. Different brands — and sometimes different batches of the same product — can produce different consistencies at the same dose. After any brand change, use the syringe flow test to confirm that the prepared drink still meets the patient’s prescribed IDDSI level before serving.
Information on this page is for educational purposes only and does not constitute medical advice. Thickener selection and dosing should be determined by a speech-language pathologist based on individual assessment.