Using thickeners

It is important to mix thickening agents appropriately to produce the required IDDSI level for the patient. Why and how medicines are given with soft food or thickened fluid explains how to find the recommended level for a patient.

Thickening agents are usually available as tubs (with scoops) or sachets of powder to be mixed with the liquid that needs thickening.

Follow product directions

Directions for use are product-specific and are provided on the product packaging. The instructions specify the amount of powder (number of ‘scoops’) to be added to a specified fluid volume (usually 200ml) to achieve IDDSI Levels 1, 2, 3 or 4.

Scoop size differs between products. Always use the right scoop for the product.

Directions will say whether to add powder to liquid or liquid to powder; this differs between products.

The directions will also indicate if the product must be left to stand to reach the desired consistency, and for how long.

Ensure patients and carers know how to prepare food and fluids to the correct IDDSI level recommended for the patient. It is important to check any fluid is the appropriate consistency at the time of administration.

Choosing thickeners

There are two main types of thickening agent: starch-based and gum-based. Different brands may also contain additional ingredients such as maltodextrin.

Local formularies may recommend specific products.

In care homes, it may be practical to recommend the same thickening agent for all patients needing thickened fluids.

Patients may prefer one type of thickener over another. Starch-based products might give a starch flavour and grainy texture, while gum-based thickeners might give a ‘slicker’ result.

The flavour of food and drink deteriorates with increasing fluid thickness, regardless of the thickener used.

Gum-based

Gums include xanthan, guar, locust bean (carob) and carrageenan. In the UK, gum-based thickening agents are mostly xanthan gum-based.

Not all gum-based thickening agents have the same properties.

Starch-based

Products typically contain modified maize starch. They are less popular than gum-based thickeners.

Starch-based thickeners must not be used to thicken macrogol (PEG) laxatives.

Drug-thickener interactions

In most cases it is preferable to give medicines with a spoonful of food or fluid the patient can swallow safely. This could be a spoonful of thickened fluid. Thickening liquid medicines is a last resort.

When looking for interactions, first consider thickened fluids in the same way as soft food. Checking if medicines can be given with food provides advice.

Studies have shown reduced dissolution of medicines mixed with thickened fluid and left overnight. Medicines should only be mixed with thickened fluid immediately before administration. This applies to both starch-based and gum-based thickeners.

Of clinical relevance is an interaction between starch-based thickeners and macrogol (polyethylene glycol (PEG)) laxatives.

Macrogol (PEG) laxatives

Starch-based thickeners must not be used to thicken macrogol (PEG) laxatives such as Movicol, Laxido, CosmoCol and Vista prep. Macrogol powder must not be dissolved in a fluid thickened with a starch-based thickener.

Mixtures of macrogol laxative and starch-based thickening agents are thin and watery. They will not thicken appropriately even if left. Fluid thickened with starch-based thickener becomes thin and watery if macrogol is added.

A Drug Safety Update highlighted this interaction. The MHRA has asked UK macrogol laxative manufacturers  to add information about the interaction to the Summary of Product Characteristics and Patient Information Leaflet.

Xanthan gum-based thickeners can be used to thicken macrogol laxatives. Some thickener brands such as Swalloweze Clear are promoted as suitable for mixing with macrogol laxatives.

Not all gum-based thickeners are the same. Thickeners based on carob gum (locust bean gum) might not be suitable for thickening macrogol laxatives.

Thickening liquid medicines provides practical advice.

Prescribing thickeners

Thickeners are not medicines. They are often Foods for Special Medical Purposes (FSMPs) intended for the dietary management of people with dysphagia. There is no Summary of Product Characteristics; product information is available from manufacturer websites. Directions for use are on the packaging.

Specific brands of thickening agents are listed in UK drug tariffs as prescribable for the management of dysphagia as approved by the Advisory Committee on Borderline Substances (ACBS). Products are available to buy without prescription, but should only be initiated under medical supervision following individual patient assessment.

Storing thickeners

Most thickening agents come in tubs with easily removable lids. A Patient Safety Alert was issued in 2015 following an incident where a care home resident died after ingesting a large amount of thickening powder that had been left within reach.

Although it is important that thickening agents remain accessible, consider the risks to patient safety. You may need to store thickeners out of reach of vulnerable patients.

Storing thickened fluids

Check the thickener container for any instructions for storage of thickened fluids.

Some (but not all) thickened fluids can be kept for 24 hours in a fridge, and it may be practical to keep them for use throughout the day.

Label jugs of thickened fluid stored in a shared fridge, such as in a care home. Clearly note the IDDSI level, thickener used, and date and time they were made up.

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