What Is IDDSI Level 0?

IDDSI Level 0, known as Thin, represents all normal unthickened liquids. This is the default consistency of water, tea, clear broth, most juices, and standard milk. In the IDDSI framework, it sits at the lowest end of the liquid thickness scale — the easiest to drink, but potentially the most dangerous for people with swallowing difficulties.

When tested using the standard IDDSI syringe flow test, a Level 0 liquid will leave 1ml or less remaining in a 10ml syringe after 10 seconds of free flow. In practice, water flows almost completely out within this window.

Common Thin Liquid Foods and Drinks

The following are all classified as IDDSI Level 0:

Water (still and sparkling)
Ice water and chilled water
Most fruit juices (apple, orange, grape, lemon water)
Tea — including Chinese teas, herbal teas, and lemon tea
Coffee and Horlicks (when fully dissolved)
Thin soups and clear broths (e.g. clear congee water, wonton soup liquid)
Low-fat milk and most soy milks
Sports drinks and rehydration solutions
Most oral nutritional supplements in liquid form (check viscosity)
Alcoholic beverages

Note: Many people are surprised that thin soup broth counts as a thin liquid. In Hong Kong, clear soup (清湯) and the liquid component of congee (粥水) are both thin liquids unless specifically thickened.

Who Should Avoid Thin Liquids?

Not everyone with dysphagia needs to avoid thin liquids — but for many patients, thin liquids are the most difficult consistency to manage safely. Thin liquids flow rapidly and unpredictably, giving the swallowing mechanism less time to respond.

Conditions where thin liquids are frequently restricted:

Stroke — post-stroke pharyngeal dysphagia, especially in the acute and sub-acute phase
Parkinson’s disease — slowed laryngeal closure and delayed swallowing reflex
Dementia — reduced swallowing initiation and awareness
Motor neurone disease (MND/ALS) — progressive bulbar palsy affecting swallowing coordination
Head and neck cancer — following surgery or radiotherapy affecting tongue, pharynx, or larynx
Acquired brain injury
Frailty and sarcopenia in older adults — generalised muscle weakness affecting swallowing

A speech therapist will determine through formal assessment (such as the GUSS or MBSS) whether a patient can safely drink thin liquids, and if not, which IDDSI level is appropriate.

Risks of Thin Liquids in Dysphagia

When thin liquids are consumed by someone who cannot safely manage them, the primary risk is aspiration — liquid entering the airway below the vocal cords. Silent aspiration (aspiration without any cough or visible sign) is particularly common in older adults with neurological conditions and is a leading cause of aspiration pneumonia.

In Hong Kong’s public hospital system, aspiration pneumonia is a significant cause of readmission among elderly patients discharged from stroke units, geriatric wards, and long-term care facilities. Identifying and managing thin liquid risk at discharge is a core part of hospital speech therapy services.

Thin Liquids in Hong Kong’s Care Context

In Hong Kong residential care homes for the elderly (RCHEs), liquid management is a critical but sometimes under-resourced area. Common challenges include:

Staff training gaps — care workers may not recognise which drinks require thickening
Thickener availability — homes may stock only one brand or type, which may not be suitable for all residents
Hydration monitoring — residents who require thickened liquids may inadvertently receive unthickened drinks from well-meaning visitors
Cantonese cuisine culture — thin soups, herbal teas, and congee water are deeply embedded in meal culture, creating real-world adherence challenges

Tools like the SeniorDeli 照護食 platform help care facilities implement consistent liquid management protocols linked to each resident’s IDDSI prescription. See seniordeli.com for more information on care food solutions for Hong Kong facilities.

When Can a Patient Return to Thin Liquids?

Some patients — particularly stroke survivors in active recovery — may progress back to thin liquids over time as swallowing function improves. This decision must always be made by a speech therapist following re-assessment. Signs that a reassessment may be warranted include:

Consistently managing the current IDDSI level without coughing or choking
Improved voice quality after eating or drinking
Reduced fatigue during meals
Improved neurological or medical status

Caregivers should never independently trial thin liquids without speech therapist approval, even if the patient reports feeling better or expresses a strong preference.

Practical Tips for Caregivers

Label all containers — clearly mark which drinks have been thickened and to what level
Inform all care staff and visitors — thin liquid restrictions must be communicated to everyone who gives food or drink
Watch for hidden thin liquids — ice cream, jelly, and certain fruits release thin liquid as they melt or are chewed
Keep a supply of thickener accessible — and ensure all carers know the correct preparation method
Document any coughing, voice changes, or wet-sounding voice after drinks and report to the medical team

Information on this page is for educational purposes only and does not constitute medical advice. IDDSI dietary levels must be determined by a speech therapist following individual assessment.