Thickened Fluids in Dysphagia: Safety Tool or Overused Solution?
- lvaughton
- Feb 19
- 7 min read
Updated: 5 days ago
Thickened fluids are commonly used in hospitals, aged care, and supported living environments to help people with dysphagia (swallowing difficulties). The idea is simple: thicker drinks move more slowly, giving the body more time to protect the airway.
But while thickened fluids can reduce visible signs of aspiration in some people, they also come with significant downsides — including dehydration, reduced quality of life, and uncertain long-term health impact (O’Keeffe, 2018; Robbins et al., 2008).
So how do we balance safety with wellbeing?
When Thickened Fluids Are Introduced Without Context
Over the past several months, I’ve seen multiple long-term community clients discharged from hospital on thickened fluids.
For some, this represented a major change from their usual baseline. In the community, they had safely managed thin fluids for years — without chest infections, hospital admissions, or respiratory compromise.
In some cases, hospital teams recommended community follow-up. In others, there was no documented review plan. Often, there had been no contact with the person’s regular speech pathologist to confirm their pre-hospital swallowing status.
This matters.
Swallowing during acute illness is often temporarily impaired. Fatigue, infection, delirium, medication changes, and deconditioning can all affect swallow safety.
Research shows that dysphagia is common during acute hospital admissions and is associated with increased length of stay and healthcare costs (Attrill et al., 2018). However, swallowing ability may improve as medical status stabilises.
Best practice dysphagia management relies on understanding trajectory, not just presentation at a single point in time.
What Are Thickened Fluids?
Thickened fluids are drinks modified with aspecific thickener to increase viscosity.
Under the International Dysphagia Diet Standardisation Initiative framework, fluids range from slightly thick to extremely thick (IDDSI, 2019).
They are commonly recommended for individuals at risk of aspiration, with the goal of slowing bolus flow and improving airway protection.
The Potential Benefits
There are some benefits for utilising thickened fluids to assist with managing swallowing difficulties.
1. Reduced Aspiration on Assessment
Research has demonstrated that thicker liquids can reduce aspiration events during instrumental swallowing assessment in some individuals (Logemann et al., 2008). Slower flow may improve timing of airway closure and bolus control.
However, reduced aspiration on imaging does not automatically translate to reduced pneumonia risk in the long term (O’Keeffe, 2018).
2. Customisable to the Individual
Different thickness levels allow clinicians to tailor recommendations to the severity of impairment.
For some individuals, mildly thick fluids may be sufficient. Others may require more protection.
3. Immediate Risk Management
In acute settings, thickened fluids are frequently used as a precautionary intervention for individuals who aspirate thin liquids (Robbins et al., 2008).
They can serve as a short-term compensatory strategy while further assessment occurs.
The Significant Drawbacks
Despite their widespread use, the evidence supporting long-term use is mixed.
1. Dehydration Risk
Many people dislike the taste and texture of thickened fluids. As a result, fluid intake often drops significantly.
Studies have shown:
People on thickened fluids may consume substantially less fluid.
Higher rates of dehydration, urinary tract infections, and fever have been observed in some groups (Robbins et al. (2008)
Longer oral processing time can reduce overall intake (Chichero, 2013)
Dehydration itself increases:
Confusion
Falls risk
Kidney complications
Hospitalisation
Ironically, in trying to prevent one health risk, we may introduce another.
O’Keeffe (2018) further questioned whether modified diets truly reduce pneumonia risk, particularly given the known dehydration risk.
2. Reduced Quality of Life
Drinking is social. It’s cultural. It’s pleasurable.
Research has shown that being prescribed thickened fluids can mean:
Missing out on what others are drinking in social settings
Feeling embarrassed in public
Reduced enjoyment of meals
Social withdrawal/social restriction
In disability settings, I have seen individuals excluded from shared food and drink experiences in the community simply because modified options were not available.
Safety must always be balanced against participation. Eating and drinking are social activities. When modifications limit participation, the psychosocial impact can be high.
3. Nutritional and Medication Concerns
Some thickening agents:
Alter medication absorption
Reduce bioavailability
Dilute nutritional value
Unless carefully monitored and supplemented, individuals may struggle to meet hydration and nutritional needs. (Steele et al., 2015)
4. Emerging Concerns About Safety
Several studies have also raised important questions:
Silent aspiration can still occur with thickened fluids.
Thickened fluids may increase pharyngeal residue in some individuals.
Animal studies have shown increased inflammatory responses when thickened fluids are aspirated compared to water.
There are currently no long-term human studies examining the effects of “extremely thick” fluids.
This does not mean thickened fluids are unsafe for everyone.
It does mean the assumption that “thicker is always safer” is overly simplistic.
The Importance of Instrumental Assessment
Swallowing decisions should not be based on observation alone.
The gold standard assessments for swallowing are:
Videofluoroscopic Swallow Study (VFSS / Modified Barium Swallow)
Flexible Endoscopic Evaluation of Swallowing (FEES)
These assessments allow clinicians to see:
Whether aspiration is occurring
When it is occurring
Whether it is cleared
How different textures behave
Whether strategies like chin tuck actually work
Without visualisation, we are inferring from surface signs.
Coughing Does Not Equal Aspiration
One of the most common misconceptions is that coughing automatically means aspiration.
It does not.
Cough is a protective reflex. It may indicate:
Penetration (material above the vocal folds)
Aspiration (material below the vocal folds)
Or simply airway irritation
Equally, aspiration can occur without any cough at all — known as silent aspiration.
The absence of coughing does not guarantee safety. The presence of coughing does not guarantee danger.
This distinction matters.
If coughing alone as a sign, leads to permanent thickened fluids, we risk over-restricting individuals unnecessarily.
A Complex Question: Why Does One Person Get Pneumonia and Another Doesn’t?
Despite decades of research, we still do not fully understand why:
Two people can aspirate
Yet only one develops pneumonia
Aspiration is only one piece of the puzzle. Other factors include:
Oral hygiene
Immune status
Mobility
Respiratory health
Volume and frequency of aspiration
Thickened fluids address only one variable.
So Where Does This Leave Us?
Thickened fluids are:
A useful tool
A short-term protective strategy
Appropriate for some individuals
But they are not:
A cure
A universal solution
Without risk
Or appropriate without review
Decisions should consider:
Baseline swallow function
Instrumental findings where possible
Hydration status
Quality of life
Goals of care
Ongoing review
Final Thoughts
Dysphagia management requires nuance.
Thickened fluids can reduce aspiration in some people. They can also reduce hydration, enjoyment, and participation.
Before recommending long-term fluid modification, we should ask:
Do we know this person’s baseline?
Has instrumental assessment been completed?
Is this a temporary precaution or a permanent change?
Have we considered alternatives?
Because safety matters. But so does quality of life.
References
Alves, Dauana Cássia et al. Difficulties in thickened water ingestion in healthy subjects. Clinical Nutrition ESPEN, Volume 22, 107 - 111
Amitrano, A. (2024). The Meal of the Person with Dysphagia. In: Dysphagia and Nutrition. Springer, Cham. https://doi.org/10.1007/978-3-031-77449-2_5
Attrill, S., White, S., Murray, J., Hammond, S., & Doeltgen, S. (2018). Impact of oropharyngeal dysphagia on healthcare cost and length of stay in hospital: A systematic review. BMC Health Services Research, 18(1), 594. https://doi.org/10.1186/s12913-018-3376-3
Chu,Yu-Hao., Chao, Jane C-J. Effectiveness of diet modification on dietary nutrient intake, aspiration, and fluid intake for adults with dysphagia: a meta-analysis of randomized controlled trials. The Journal of nutrition, health and aging; Volume 29, Issue 4, April 2025, 100486. https://doi.org/10.1016/j.jnha.2025.100486
Cichero, J.A. Thickening agents used for dysphagia management: effect on bioavailability of water, medication and feelings of satiety. Nutr J 12, 54 (2013). https://doi.org/10.1186/1475-2891-12-54
Eating and Drinking Difficulties (Dysphagia) (2026) https://www.newcastle-hospitals.nhs.uk/services/stroke-unit/life-after-stroke/eating-and-drinking-difficulties-dysphagia
International Dysphagia Diet Standardisation Initiative (IDDSI). (2019). Complete IDDSI framework detailed definitions. https://iddsi.org
Langmore, S. E., Terpenning, M. S., Schork, A., Chen, Y., Murray, J. T., Lopatin, D., & Loesche, W. J. (1998). Predictors of aspiration pneumonia: how important is dysphagia?. Dysphagia, 13(2), 69–81. https://doi.org/10.1007/PL00009559
Logemann, J. A., et al. (2008). A randomized study of three interventions for aspiration of thin liquids in patients with dementia or Parkinson’s disease. Journal of Speech, Language, and Hearing Research, 51(1), 173–183. https://doi.org/10.1044/1092-4388(2008/013)
McCurtin, A., Collins, L., King, L., Lazenby-Paterson, T., Lisiecka, D., Leslie, P., … Smith, A. (2024). Beyond thickened liquids: for your consideration. Journal of Clinical Practice in Speech-Language Pathology, 26(2), 128–166. https://doi.org/10.1080/22000259.2024.2359368
Miles, A., McFarlane, M., Scott, S., & Hunting, A. (2018). Cough response to aspiration in thin and thick fluids during FEES in hospitalized inpatients. International journal of language & communication disorders, 53(5), 909–918. https://doi.org/10.1111/1460-6984.12401
Moloney, Jennifer & Walshe, Margaret. (2017). “I had no idea what a complicated business eating is…”: a qualitative study of the impact of dysphagia during stroke recovery. Disability and Rehabilitation. 40. 1-8. 10.1080/09638288.2017.1300948.
Nativ-Zeltzer, N., Kuhn, M. A., Imai, D. M., Traslavina, R. P., Domer, A. S., Litts, J. K., Adams, B., & Belafsky, P. C. (2018). The effects of aspirated thickened water on survival and pulmonary injury in a rabbit model. The Laryngoscope, 128(2), 327–331. https://doi.org/10.1002/lary.26698
Nativ-Zeltzer, N., Ueha, R., Nachalon, Y., Ma, B., Pastenkos, G., Swackhamer, C., Bornhorst, G. M., Lefton-Greif, M. A., Anderson, J. D., & Belafsky, P. C. (2021). Inflammatory Effects of Thickened Water on the Lungs in a Murine Model of Recurrent Aspiration. The Laryngoscope, 131(6), 1223–1228. https://doi.org/10.1002/lary.28948
O’Keeffe, S. T. (2018). Use of modified diets to prevent aspiration in oropharyngeal dysphagia: Is current practice justified? BMC Geriatrics, 18(1), 167. https://doi.org/10.1186/s12877-018-0839-7
Robbins, J., et al. (2008). Comparison of two interventions for liquid aspiration on pneumonia incidence: A randomized trial. Annals of Internal Medicine, 148(7), 509–518. https://doi.org/10.7326/0003-4819-148-7-200804010-00007
Royal College of Speech and Language Therapists (RCSLT). (2023). Position paper on the use of thickened fluids in the management of dysphagia. https://www.rcslt.org
Steele, C., Greenwood, C., Ens, I. et al. Mealtime Difficulties in a Home for the Aged: Not Just Dysphagia . Dysphagia 12 , 43 –50 (1997). https://doi.org/10.1007/PL00009517
Wilkinson, T. J., et al. (2017). Fluid intake and dehydration in older adults receiving thickened fluids: A clinical nutrition perspective. Clinical Nutrition, 36(5), 1380–1386.
