Thickeners are the most widely used intervention for managing liquids in dysphagia. Choosing the wrong type or preparing them incorrectly can increase rather than reduce aspiration risk. This guide explains the two main thickener types, IDDSI level preparation, available products, and the most common clinical and caregiver errors.
| IDDSI Level | Description | Flow Test | Xanthan Gum Amount (per 250mL water) |
|---|---|---|---|
| Level 1 (Slightly Thick) | Slightly thicker than water | Flows quickly off fork | ~1 tsp (see product label) |
| Level 2 (Mildly Thick) | Similar to full-fat milk | Drips slowly off fork | ~1.5-2 tsp |
| Level 3 (Moderately Thick) | Flows off fork in a ribbon | Pours like a thick syrup | ~2.5-3 tsp |
| Level 4 (Extremely Thick / Pudding) | Holds shape; like yogurt or pudding | Does not flow off fork; can be scooped | ~4-5 tsp |
Important notes:
| Product | Type | Market | Notes |
|---|---|---|---|
| Resource ThickenUp Clear (Nestlé) | Xanthan gum | US, UK, EU, Asia | Clear/transparent; widely recommended by SLPs |
| Thick-It Original (Medline) | Starch-based | US | Original formula; note amylase degradation risk |
| Thick-It Clear (Medline) | Xanthan gum | US | Clear version; improved stability vs original |
| Nutilis Clear (Nutricia) | Xanthan gum | UK, EU, Australia | Frequently used in NHS settings |
| Simply Thick EasyMix | Xanthan gum | US | Gel-form individual sachets; popular in clinical settings |
| Thick & Easy Clear (Hormel) | Xanthan gum | US, Hong Kong | Transparent type; does not alter drink appearance |
Problem: Starch thickeners can lose a significant portion of their viscosity within hours due to salivary amylase in shared containers or continued enzymatic breakdown — the liquid may no longer meet the prescribed IDDSI level by the time it’s consumed.
Correction: Prepare starch-thickened drinks immediately before consumption. If advance preparation is necessary, use xanthan gum-based thickeners; store in a sealed container for no more than 24 hours.
Problem: Very hot liquids (above ~70°C) can affect starch thickener performance. Xanthan gum is more heat-stable but still shows some variation.
Correction: Allow hot drinks to cool slightly (below ~60°C) before adding thickener. Follow the product’s temperature guidelines.
Problem: High-acidity drinks (orange juice, lemonade) can reduce starch thickener effectiveness; may require more powder than usual.
Correction: Use xanthan gum-based thickeners for acidic beverages. Always test the final viscosity — do not assume the standard amount is sufficient for every liquid type.
Problem: Caregivers and family members often estimate viscosity by appearance or how the drink “feels,” which is highly inaccurate.
Correction: Teach caregivers to use the IDDSI Fork Drip Test (hold a fork horizontally over a glass; correct viscosity drips at the expected rate) and the spoon tilt test to objectively verify the IDDSI level matches the prescription.
Problem: Switching brands without re-testing can result in the same volume producing a different viscosity level.
Correction: When changing products, re-establish the dose from scratch using the new product’s guidelines and confirm with testing before serving.
Resistance to thickened drinks is common and clinically significant:
| Starch-Based | Xanthan Gum-Based | |
|---|---|---|
| Salivary amylase stability | ✕ Degrades over time | ✓ Stable |
| Acidic drink performance | Variable | Stable |
| Heat stability | Lower | Higher |
| Transparency | Opaque | Clear |
| IDDSI recommendation | Not preferred | Preferred |
| Cost | Lower | Slightly higher |
Xanthan gum-based thickeners are the IDDSI-preferred choice for clinical safety. Correct preparation — right amount, immediate mixing, objective viscosity testing — is as important as choosing the right product type. Any changes to a thickening prescription should be made in consultation with a speech-language pathologist.