[Tolerability of oral administration of carboxymethylcellulose in two patients presenting anaphylactic reaction after carboxymethylcellulose injection]

Carboxymethylcellulose is a high-molecular-weight polysaccharide molecule used as a binding agent, for coating molecules and to increase the viscosity of formulations. It is present in a large number of pharmaceutical products but is also found in food and cosmetics.We report two cases of patients who presented anaphylactic reactions immediately after localised corticosteroid injections; intra-articular for the first and intralesional for the second. Allergological testing for different corticosteroids and carboxymethylcellulose by means of prick-tests and intradermal testing indicated that the immediate hypersensitivity reaction was caused by the excipient, carboxymethylcellulose. The excellent safety of oral reintroduction of carboxymethylcellulose in a pharmaceutical preparation in these two patients confirmed that this large molecule is not absorbed through the digestive system.The avoidance list of products containing carboxymethylcellulose could be greatly reduced and limited to only injectable pharmaceutical preparations containing carboxymethylcellulose and to oral contrast media containing large quantities of carboxymethylcellulose.