Abstract: | The most common side effects of interferon-beta therapy following subcutaneous administration include pain, inflammation and induration at the injection site, which occur in approximately 20–60% of patients. Besides, transient injection-site erythema is frequently seen in beta-interferon therapy. Less frequent reactions at injection sites include vascular thrombosis, mucinosis, dermal and systemic sclerosis, necrosis, and ulceration. Here, we report a 44-year-old case diagnosed with multiple sclerosis, who developed pain and swelling following interferon-beta 1a treatment after an improperly administered intramuscular injection; and with this case report, we would like to draw attention to septal panniculitis, a serious drug complication, that develops following interferon-beta 1a treatment after an improperly administered intramuscular injection. |