Using thickeners of different types for patients with swallowing difficulties

Karoline Brennan, Senior Medicines Information Pharmacist, North West Medicines Information CentrePublished

Gum and starch based thickeners are available; drug-thickener interactions are possible and should be avoided.

General advice

Defining and identifying thickness of fluids and food for patients with swallowing difficulties

How fluid thickness and food texture are defined for patients with swallowing difficulties, and how to find the recommended level for a patient.


It is important that thickening agents are mixed appropriately in order to produce the required IDDSI Level for the patient.

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

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

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

The directions on the packaging will say whether to add powder to liquid or liquid to powder; this differs between products.

The directions will also say if the product has to stand to reach the desired consistency.

Choosing between starch-based and gum-based thickeners

There are two main types of thickening agent: starch-based (typically modified maize starch) and gum-based.


Gums include xanthan, guar, locust bean (aka carob) and carrageenan. Not all gum-based thickening agents have the same properties. In the UK, gum-based thickening agents are mostly xanthan gum-based. Different brands may also contain additional ingredients such as maltodextrin.


Starch-based thickening agents were widely used in the 1990s but gum-based thickening agents have gained popularity more recently.


Patients may have a preference for 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 has been shown to deteriorate with increasing fluid thickness, regardless of the thickener used.

Drug-thickener interactions

If thickeners are used to thicken medicines, there is the potential for a drug-thickener interaction. Information on interactions between medicines and thickeners is limited.

Macrogol (PEG) laxatives and starch-based thickeners
  • Starch-based thickeners must NOT be used to thicken Macrogol (PEG) laxatives (e.g. Movicol, Laxido, Cosmocol, Klean Preg, Vista prep), and macrogol (PEG) powder must NOT be dissolved in a fluid thickened with a starch-based thickener as the resulting mixture is thin and watery.
  • The MHRA has asked manufacturers of UK macrogol (PEG) laxative products add information about this potential interaction to the Summary of Product Characteristics and the Patient Information Leaflet.
  • Xanthan gum-based thickeners can be used to thicken macrogol (PEG) laxatives. Some brands of thickener (e.g. Swalloweze Clear and Thick & Easy Clear) are promoted as being suitable for mixing with macrogol (PEG) laxatives, and provide information on how they should be mixed.
  • Not all gum-based thickeners are the same. Thickeners based on carob gum (locust bean gum) might not be suitable for thickening macrogol (PEG) laxatives.

Other specific areas

Storage and regulation of thickeners and thickened fluids

Thickeners and thickened fluids have different storage requirements and are regulated in a particular manner.

Thickening liquid medicines

Thickening liquid medicines should not be used routinely: it is difficult to check fluid consistency which can affect whether the medicine is swallowed safely.

Read more

Swallowing difficulties

All our advice on using medicines safely and effectively in patients with swallowing difficulties