Immediate hypersensitivity reaction to carboxymethylcellulose in lidocaine jelly and dimethicone drops: A case report and mini-review

Excipient allergies are rare and difficult to diagnose. Carboxymethylcellulose (CMC, carmellose sodium) is an anionic water-soluble polymer derived from native cellulose, that is, used as an excipient. Here, we report a case of urticaria caused by the CMC in lidocaine jelly and dimethicone drops, which had used for upper gastrointestinal endoscopy. CMC is widely used in pharmaceutical preparations, food additives, and other pharmaceuticals, and its use is increasing. However, there are few reports on immediate hypersensitivity reactions because substances containing CMC. Previous reports and our case suggest that excipients, such as CMC, can be potential hidden allergens.