What is the IDDSI flow test?

The IDDSI flow test uses a 10 mL syringe held vertically for 10 seconds to measure how far a thickened liquid flows. The volume remaining in the syringe determines the IDDSI level: Level 1 (Slightly Thick) through Level 4 (Extremely Thick). It is the internationally standardised method for verifying thickened drink consistency.

How do I know if a drink is the right IDDSI level?

Perform the IDDSI flow test immediately after preparation and before serving. The residual volume in a 10 mL syringe after 10 seconds tells you the level achieved. Compare this result against the target level prescribed by the individual's speech therapist or dietitian.

Which IDDSI level should I use for my patient?

The appropriate IDDSI thickened fluid level for a person with dysphagia must be determined by a qualified speech-language pathologist through a clinical swallowing assessment. This tool provides general IDDSI flow test reference information only — it is not a clinical recommendation.

IDDSI Thickened Fluid Test Guide

Select your fluid type and target IDDSI level to instantly see the correct flow test criteria and preparation guidance for dysphagia-safe drinks.

Select fluid type

Select target IDDSI level

← Select a fluid type and IDDSI level above to see the verification criteria.

Related resources

IDDSI Framework Guide
All 8 IDDSI levels explained with testing methods and care-home compliance guidance.
EAT-10 Swallowing Screener
Free validated 10-question dysphagia self-screening tool.
SeniorDeli Clear Thickener
Our IDDSI-verified thickening powder for dysphagia-safe drinks.
IDDSI Compliance Guide for Care Homes
Step-by-step guide to achieving and maintaining IDDSI compliance across your RCHE.

IDDSI Thickened Fluid Test Guide

Related resources

IDDSI Framework Guide

EAT-10 Swallowing Screener

SeniorDeli Clear Thickener

IDDSI Compliance Guide for Care Homes