Kevin V. Thomas, BA; Daniel D. Bennett, MD; Justin Endo, MD, MHPE
Introduction: Fremanezumab is a humanized monoclonal antibody administered through a subcutaneous injection. It is used for treatment of migraines, and occasional injection site reactions have developed after usage.
Case Presentation: This case report describes a nonimmediate injection site reaction on the right thigh of a 25-year-old female patient after starting treatment with fremanezumab. The injection site reaction presented as 2 warm, red annular plaques 8 days following a second injection of fremanezumab and about 5 weeks following the first injection. She was prescribed a 1-month course of prednisone that relieved her symptoms of redness, itching, and pain.
Discussion: Similar nonimmediate injection site reactions have been reported before, but this particular injection site reaction was significantly more delayed.
Conclusions: Our case illustrates that injection site reactions to fremanezumab can be delayed after the second dose and may require systemic therapy to alleviate symptoms.