Thickened Liquids For Dysphagia: What, When, Why, & How

Thickened liquids are a common treatment option for people with dysphagia. But should you recommend it to your patient?

In this article, you’ll learn the whats, whens, whys, and hows of recommending thickened liquids for dysphagia, including what recent evidence says.

For bestselling patient handouts and worksheets, see the Adult Speech Therapy Starter Pack

What Are Thickened Liquids?

A thickened liquid is any liquid that is naturally thicker or has been modified to be thicker than a thin liquid. Examples of thin liquids are water, milk, and coffee. 

Thickened liquids levels were standardized by The International Dysphagia Diet Standardisation Initiative (IDDSI) of 2019. 

Here are the IDDSI liquid levels:

• Thin – Level 0​
• Slightly thick – Level 1​
• Mildly thick – Level 2​
• Moderately thick – Level 3​
• Extremely thick – Level 4​

You can thicken liquids with a starch-based powder or a gum-based gel. All liquids can be thickened, although some thicken easier and faster than others.

How To Thicken Liquids

Below is a video made by Gaylord Speciality Healthcare that demonstrates ways to thicken liquids for dysphagia.

Why Do We Thicken Liquids?

Thickening liquids is a compensatory strategy to improve symptoms of dysphagia in some patients. 

It does this by slowing the flow of the liquid bolus. By slowing down the bolus’ transit, thickened liquids may prolong and increase UES opening (and may increase the duration of pharyngeal peristaltic waves, Dantas et al., 1990). 

A study of 483 patients who had undergone a VFSS at a university hospital found that thickened liquids significantly decreased the incidence of penetration-aspiration (Masuda et al., 2022).

In this same study, the 23 patients on thickened liquids who did develop aspiration pneumonia were more likely to have a history of pneumonia and poor performance status (decreased daily activity, physical ability, and ability to care for self according to the ECOG performance status).

Thickened liquids may also increase tongue-palate pressure compared to thin liquids, which can improve the efficiency of swallowing (Steele et al., 2014)

However, being on thickened liquids has significant downsides. We’ll explore these next.

Why Not Thicken Liquids?

Recent literature suggests that an instrumental exam (i.e., VFSS, FEES) should be done before recommending thickened liquids. This includes thickening liquids for bedside evaluations. 

This is because of growing evidence that thickeners may not be as benign as we once thought. Here’s where some controversy comes in! 

Before getting stressed, remind yourself that the field of dysphagia is ever-evolving. We do the best we can with what we have, then pivot as needed.

Although solid evidence supports thickened liquids as a dysphagia treatment option for some, it may not always be the primary or safest tool in your dysphagia toolkit.

A 2018 study by Miles et al. found that patients were more likely to silently aspirate thickened liquids than thin liquids. In fact, just because a patient coughed on thin liquids and didn’t cough on thickened liquids didn’t mean they weren’t silently aspirating on both! 

A systematic review of the adverse effects of thickened liquids found that they increased the risk of dehydration and its side effects (including frequent UTIs, impaired cognition, increased falls), decreased quality of life, and did not decrease the risk of pneumonia (Werden Abrams et al., 2023).

There are also extensive animal studies that demonstrate possible harmful pulmonary effects of aspirating thickened liquid (Nativ-Zeltzer et al., 2018; Nativ-Zeltzer et al., 2021; & Araie et al., 2020).

When Should You Recommend Thickened Liquids For Dysphagia?

So, when should you recommend thickened liquids for your patients with dysphagia?

During an instrumental exam (VFSS, FEES), the speech-language pathologist will trial thickened liquids as indicated. If the patient demonstrates a level of dysphagia in which a thickened liquid is safest, then it would be appropriate to recommend thickened liquids.

The goal with thickened liquids is to use them for a short period of time. Repeat an instrumentational assessment to advance their consistencies.

What If You Can’t Do An Instrumental Exam?

What can you do if you’re in a situation where an instrumental exam is just not possible for a patient who may benefit from thickened liquids?

For example, your patient is homebound and leaving even for medical appointments is very taxing. Or they refuse to complete an instrumental.

Discuss the risks and benefits of thickening liquids without an instrumental exam with the patient, their family, and the medical team. Learn the patient’s goals, needs, and preferences and prioritize them when making recommendations.

Also, consider which patients are more likely to develop aspiration pneumonia. 

As stated earlier, patients on thickened liquid were more likely to develop aspiration pneumonia if they had poor performance status (poor daily activity, physical ability, and ability to care for themselves) and a history of aspiration pneumonia (Masuda et al., 2022). 

Sanivarapu et al., 2024, reported on the prevalence of aspiration pneumonia in specific patient populations:

• Head and neck cancer and its treatment: almost 70% prevalence (lifetime)
• Stroke: Between 3% to 50%
• Hospitalized patients with Parkinson’s disease or dementia: up to 11% over 3 months
• Intubation with mechanical ventilation (more than 3 days): 20-35%
• Aspiration pneumonia is a common complication of advanced multiple sclerosis, motor neuron diseases, and Huntington’s disease

If the patient is not a good candidate, consider alternatives to thickening liquids. These may include (McCurtin et al., 2024):

• Sensory enhancement (carbonation, menthol, capsaicin, etc.; Ebihara et al., 2006; Wang et al., 2019)
• Respiratory muscle strength training to improve cough and respiratory strength
• Swallow skills training
• Aggressive oral care
• Environmental and mealtime modifications (smaller bolus, etc.)
• Frazier Water Protocol

How To Improve Hydration?

In her dysphagia series, Angela Mansolillo offers evidence-based ways to improve hydration for patients on thickened liquids (n.d.):

• Offer liquids more often! Set daily liquid volume goals
• Give options for thickeners (starch, gel, naturally thick liquids) to find which is most appetizing for each patient
• Offer pre-thickened liquids (may be more appetizing and improve hydration)
• Train patients, family, and staff about how to consistently thicken liquids
• Work with a dietician to choose foods with more fluid content
• Use the Frazier Water Protocol

References

• American Speech-Language-Hearing Association. (n.d.). Adult Dysphagia. (Practice Portal). Retrieved November, 2023, from www.asha.org/Practice-Portal/Clinical-Topics/Adult-Dysphagia/.
• Araie, T., Minagi, H. O., Usami, Y., Ikai, K., Sakai, M., Gojo, N., Nohara, K., & Sakai, T. (2020). Effect of xanthan gum-thickened liquid aspiration on the lungs in a mouse model. Oral Science International, 17(2), 78-85. https://doi.org/10.1002/osi2.1047
• Brewer, C., Aparo, M. (2021) The Adult Speech Therapy Starter Pack. Harmony Road Design Publishing.
• Dantas, R. O., Kern, M. K., Massey, B. T., Dodds, W. J., Kahrilas, P. J., Brasseur, J. G., Cook, I. J., & Lang, I. M. (1990). Effect of swallowed bolus variables on oral and pharyngeal phases of swallowing. The American journal of physiology, 258(5 Pt 1), G675–G681. https://doi.org/10.1152/ajpgi.1990.258.5.G675
• Ebihara, T., Ebihara, S., Watando, A., Okazaki, T., Asada, M., Ohrui, T., Yamaya, M., & Arai, H. (2006). Effects of menthol on the triggering of the swallowing reflex in elderly patients with dysphagia. British Journal of Clinical Pharmacology, 62(3), 369-371. https://doi.org/10.1111/j.1365-2125.2006.02666.x
• Mansolillo, A. (n.d.). Clinical Assessment of Swallowing, Part 3 – Putting it All Together. Medbridge. [Online Course]. Retrieved from https://www.medbridge.com/courses/details/clinical-assessment-of-swallowing-part-3-putting-it-all-together
• Masuda, H., Ueha, R., Sato, T., Goto, T., Koyama, M., Yamauchi, A., Kaneoka, A., Suzuki, S., & Yamasoba, T. (2022). Risk Factors for Aspiration Pneumonia After Receiving Liquid-Thickening Recommendations. Otolaryngology–head and neck surgery : official journal of American Academy of Otolaryngology-Head and Neck Surgery, 167(1), 125–132. https://doi.org/10.1177/01945998211049114
• McCurtin, A., Byrne, H., Collins, L., McInerney, M., Lazenby-Paterson, T., Leslie, P., & Smith, A. (2023). Alterations and Preservations: Practices and Perspectives of Speech-Language Pathologists Regarding the Intervention of Thickened Liquids for Swallowing Problems. https://doi.org/10.1044/2023_AJSLP-23-00226
• 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
• 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
• Sanivarapu, R. R., Vaqar, S., & Gibson, J. (2024). Aspiration Pneumonia. In StatPearls. StatPearls Publishing.
• Steele, C. M., Molfenter, S. M., Péladeau-Pigeon, M., Polacco, R. C., & Yee, C. (2014). Variations in tongue-palate swallowing pressures when swallowing xanthan gum-thickened liquids. Dysphagia, 29(6), 678–684. https://doi.org/10.1007/s00455-014-9561-6
• Wang, Z., Wu, L., Fang, Q., Shen, M., Zhang, L., & Liu, X. (2019). Effects of capsaicin on swallowing function in stroke patients with dysphagia: A randomized controlled trial. Journal of Stroke and Cerebrovascular Diseases, 28(6), 1744-1751. https://doi.org/10.1016/j.jstrokecerebrovasdis.2019.02.008
• Werden Abrams, S., Gandhi, P., & Namasivayam-MacDonald, A. (2023). The Adverse Effects and Events of Thickened Liquid Use in Adults: A Systematic Review. American journal of speech-language pathology, 32(5), 2331–2350. https://doi.org/10.1044/2023_AJSLP-22-00380