Hair loss associated with use tioguanine (Thiosix) for inflammatory bowel disease

Over the last five years, the Netherlands Pharmacovigilance Centre Lareb received twenty reports of hair loss by women associated with the use of tioguanine for bowel disease. For most patients the hair loss started within one month after start of tioguanine. This is similar to hair loss seen during chemo therapy. There was a difference in the reported degree of hair loss, however baldness was not reported. 

There are two strengths of tioguanine available on the Dutch market. Lanvis (40 mg) is indicated for the treatment of acute myeloid or lymphatic leukaemia. Thiosix (10 mg and 20 mg) is available under a conditional approval and indicated for the treatment of inflammatory bowel disease, like Crohn’s disease and ulcerative colitis. The reports received by Lareb were mainly about Thiosix. 

Tioguanine is a cytotoxic drug. For Lanvis hair loss is described in the Summary of Product Characteristics (SPC). For Thiosix hair loss in not described. Hair loss can also occur due to the bowel disease itself, especially during an exacerbation of the disease. Stress and a lack of good nutrients can also cause hair loss. This type of hair loss however often occurs after two to three months. Considering the specific time pattern and a pharmacological mechanism of tioguanine that suits hair loss, this signal describes a possible association of alopecia with the use of low dose tioguanine (Thiosix). 

Read the analysis of the reports.