Background Acute Generalised Exanthematous Pustulosis (AGEP) is a rash with multiple sterile intraepidermal or subcorneal non‐follicular pustules on edematous papules, with a sudden development and rapid evolution, triggered by drugs, vaccination, insect bites, exposure to mercury, and allergens. Objectives and Methods We describe a female patient who developed extensive and abnormally prolonged AGEP following exposure to terbinafine and SARS‐CoV vaccine. A detailed review of terbinafine‐induced‐AGEP cases was performed, with the aim of evaluating if the AGEP criteria would follow a different pattern when the disease is triggered by this drug. A PubMed search helped retrieve all terbinafine‐induced AGEP case reports. AGEP‐specific Sideroff criteria were analysed in terbinafine‐induced cases and compared to other trigger causes. Conclusions When the AGEP causative drug was terbinafine, a delay in recovery was observed, compared to the existing AGEP criteria when other causes are considered. Terbinafine frequently leads to delayed resolution AGEP probably due to the presence of the drug in the skin for several weeks after exposure, even after discontinuation, and the disease severity may be potentialised by additional factors such as concomitant viral infections or vaccination.