Why Do Stroke Patients Need Thickened Liquids?
After a stroke, many patients find thin liquids — water, tea, soup — difficult to control safely. Thin liquids flow quickly; if the pharyngeal swallowing reflex has been disrupted by the stroke, liquid can enter the airway before the protective reflex triggers, causing aspiration.
Thickened liquids slow the flow of fluid, giving the impaired swallowing system more time to trigger its protective reflexes, substantially reducing aspiration risk.
Important: The IDDSI thickness level for a patient’s liquids must be prescribed by a speech-language pathologist (SLP) following clinical assessment. Liquids that are too thick carry their own risks (pharyngeal residue that can be aspirated after swallowing); liquids too thin provide insufficient protection.
IDDSI Liquid Thickness Levels
| Level | Name | Characteristic | Syringe Flow Test |
|---|---|---|---|
| Level 0 | Thin | Plain water, tea | Empties completely in 10 sec |
| Level 1 | Slightly Thick | Flows fast; slightly resistant | 1–10 ml remains |
| Level 2 | Mildly Thick | Drinkable from cup; noticeable resistance | 4–10 ml remains |
| Level 3 | Moderately Thick | Pours slowly; can still drink from cup | 0–4 ml remains |
| Level 4 | Extremely Thick | Must be eaten with a spoon; cannot be cup-drunk | 0 ml (does not flow) |
Syringe flow test: fill a 10 ml syringe; hold upright for 10 seconds; measure volume remaining.
Thickener Options Available in Hong Kong
Xanthan Gum-Based Thickeners
Advantages:
- Stable consistency in both hot and cold liquids (does not continue to thicken as temperature changes)
- Shear-thinning properties reduce viscosity momentarily during swallowing, easing bolus passage
- Excellent IDDSI test repeatability
Available in HK: Pharmacies and medical supply stores carry brands such as Nutilis Clear and ThickenUp Clear.
Starch-Based Thickeners
Considerations:
- Unstable in hot liquids; continues to thicken after preparation
- More difficult to achieve a consistent IDDSI level
- Generally used when budget is the primary constraint
Emergency alternative: Plain cornflour (raw starch) from supermarkets can serve as a very short-term substitute but is not recommended for regular use due to inconsistency.
How to Prepare Thickened Drinks Correctly
- Measure the liquid accurately (use a graduated measuring jug)
- Add thickener at the prescribed dose (follow the SLP’s instructions exactly — do not estimate)
- Stir immediately and thoroughly (xanthan gum needs 10–15 seconds of brisk stirring; starch-based may need longer)
- Wait 1–2 minutes (allow the thickener to fully activate)
- Verify with the syringe flow test (especially after switching brands or preparing for the first time)
Common Mistakes to Avoid
- Estimating doses: Different brands produce different consistencies at the same volume. Always use a measuring spoon.
- Skipping the resting time: Serving before the thickener has fully activated results in thinner consistency than prescribed.
- Not re-verifying after a brand switch: Switching brands without re-testing is a patient safety risk.
- Using starch-based thickener in hot drinks: Heat causes continued starch gelatinisation, progressively increasing thickness beyond the target level.
Daily Hydration Management
Daily Fluid Targets
Adults generally need approximately 1,500–2,000 ml of fluid daily (including fluid from food). Thickened liquids can meet this need, but some patients refuse thickened drinks due to altered taste or texture, leading to dehydration.
Strategies to Improve Acceptance
- Use a xanthan gum-based thickener (clear, virtually tasteless) to minimise texture and flavour change
- Offer a variety of thickened drinks: filtered chrysanthemum tea, thickened fruit juice, thickened milk
- Use a nosey cup or cut-out cup to allow drinking without tilting the head back
- Offer small volumes (approximately 100–150 ml) frequently throughout the day
Monitoring for Dehydration
Watch for:
- Dark yellow urine or reduced urination frequency
- Dry mouth or reduced skin turgor
- Confusion or increased disorientation (especially in elderly patients)
- Worsening constipation
If you suspect dehydration, consult the patient’s doctor or SLP about adjusting the hydration strategy.
Handling Specific Drinks
Chinese Herbal Teas and Broths
- Most Chinese herbal teas are Level 0 thin liquids and must be thickened to the prescribed level
- Strain out any sediment or herb particles before thickening
- Nourishing soups containing solid ingredients (goji berries, red dates) should be strained; the liquid portion requires thickening
Alcoholic Beverages
- Some patients may wish to have a small amount of alcohol on special occasions
- Alcohol is a Level 0 thin liquid and must also be thickened if prescribed
- Discuss this with the SLP and the prescribing doctor, particularly regarding interactions with any medications
Communicating in Hospital and Care Home Settings
- Carry the SLP’s written dysphagia diet prescription to ensure all staff provide liquids at the correct IDDSI level
- Ask which thickener brand the facility uses and confirm whether it matches the home product or has been re-verified at the new brand’s dose
- On discharge or transfer, ensure the receiving team receives an up-to-date written prescription
This guide provides general information for Hong Kong stroke patients and families. It does not replace an individualised speech-language pathology assessment. Please consult your SLP for guidance specific to your situation.