University of Wisconsin–Madison Medical College of Wisconsin

Delayed Injection Site Reaction to Fremanezumab for Chronic Migraine Treatment

Kevin V. Thomas, BA; Daniel D. Bennett, MD; Justin Endo, MD, MHPE

WMJ. 2023;122(2):146-148.

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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.

Author Affiliations: University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin (Thomas, Bennett, Endo).
Corresponding Author: Justin Endo, MD, MHPE, University of Wisconsin School of Medicine and Public Health, 1 S Park St, 7th Floor, Madison, WI 53715; phone 608.287.2620, email; ORCID ID 0000-0001-7580-583X
Acknowledgements: The patient gave written consent for their photographs and medical information to be published in print and online and with the understanding that this information may be publicly available.
Financial Disclosures: None declared.
Funding/Support: None declared.
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