Recurrent hypofibrinogenemia with interleukin-6 inhibitors tocilizumab and sarilumab: A case report

Hypofibrinogenemia is a rare but clinically significant adverse effect of interleukin-6 (IL-6) receptor blockade, most associated with tocilizumab. We present a case of recurrent hypofibrinogenemia in an elderly patient with seronegative rheumatoid arthritis who developed bleeding complications during tocilizumab therapy and subsequently experienced recurrent hypofibrinogenemia after transitioning to sarilumab. This case highlights that hypofibrinogenemia likely represents a class effect of IL-6 blockade and that switching between IL-6 inhibitors may not mitigate the risk.