‘The use of thickened fluids for swallowing problems has come under scrutiny’

Thickened fluids are a common treatment for people who have difficulty swallowing drinks. Drinks may be thickened naturally, like smoothies, or with commercial gum-based or starch-based powders or gels.

By flowing more slowly, thickened fluids can allow for better control of drinks in the mouth and can prevent or reduce patient distress or discomfort related to severe coughing on thin fluids.

Thickened fluids have been shown in many studies to reduce aspiration (fluid entering into the lungs).

However, the use of thickened fluids in the treatment of swallowing problems has come under increased scrutiny, raising questions about their benefit and concerns about their potential harms.

The Royal College of Speech and Language Therapists (RCSLT) called on the expertise of speech and language therapists, other health professionals, academics and patient groups to review the evidence about thickened fluids and to create a position paper to guide evidence-based practice (RCSLT, 2024).

“Thickened fluids do not improve health, survival or quality of life for patients”

Tracy Lazenby-Paterson

While there is evidence that thickened fluids can reduce aspiration and cough-related distress, thickened fluids do not reduce or prevent risk of respiratory infections such as aspiration pneumonia, nor do they improve health, survival or quality of life for patients (Hansen et al, 2022).

Thicker fluids might reduce aspiration in some cases, but they cannot prevent it, and many studies have shown that thickened fluids can be aspirated. Thick fluids tend to leave residue in the mouth and throat, and they carry a higher bacterial load than thin fluids.

The cilia in the lungs are unable to move solid material, which may explain why the literature suggests a higher propensity for developing pneumonia when thicker consistencies are aspirated (Nativ-Zeltzer et al, 2020).

Scrupulous mouth care is essential for patients who choose to have thickened fluids, especially in hospitals and nursing homes where oral infection control can be under-prioritised (Beacher and Sweeney, 2015).

Studies generally report that most patients prefer not to have thickened fluids, and that this treatment can have a worsening impact on quality of life.

This can be due to difficulties with their preparation, their unpleasant taste and texture, and their adverse effects on health, such as dehydration, loss of appetite and altered absorption of certain medications.

The risk of these adverse effects may increase in weak or frail patients who have insufficient strength or stamina to swallow thicker consistency drinks safely or efficiently (Hansen et al, 2022).

A cough alone is not a reliable indicator of aspiration or pneumonia. Coughing is a useful defence mechanism to help clear the throat and airway, and it does not always need to be treated or eliminated. Nevertheless, for some patients, thickened fluids can provide comfort and improve drinking, especially if they are unable to drink thin fluids due to significant distress from extreme coughing.

In light of the uncertainty surrounding this treatment, it is important to carefully consider whether thickened fluids are necessary. Any use of thickened fluids must be carefully documented and reviewed after robust assessment of their benefit-burden profile, and by a qualified dysphagia practitioner, usually a speech and language therapist. Patient wishes, quality of life and their right to choose or refuse this treatment are central to this process.

It is vital that patients, their families and their carers have sufficient information about the potential benefits and burdens of thickened fluids to allow them to make an informed decision about whether this treatment is right for them.

Tracy Lazenby-Paterson is professional adviser in dysphagia in adults with intellectual disabilities, Royal College of Speech and Language Therapists, and chair of the Scotland Dysphagia Clinical Excellence Network