Background Due to coronavirus disease 2019 (COVID-19) pandemic response measures, the administration of botulinum toxin (BTX) was delayed for many patients during the first lockdown period in Portugal. Objectives To review the impact of postponing BTX treatment on migraine control. Methods This was a retrospective, single-center study. Patients with chronic migraine who had done at least three previous BTX cycles and were considered responders were included. The patients were divided into two groups, one that has had their treatment delayed (group P), and one that has not (controls). The Phase III Research Evaluating Migraine Prophylaxis Therapy (PREEMPT) protocol was used. Migraine-related data were obtained at baseline and at three subsequent visits. Results The present study included two groups, group P (n = 30; 47.0 ± 14.5 years; 27 females, interval baseline -1^st visit: 5.5 [4.1–5.8] months) and the control group (n = 6; 57.7 ± 13.2 years; 6 females; interval baseline–1^st visit 3.0 [3.0–3.2] months). No difference between the groups was present at baseline. When compared to baseline, the number of days/month with migraine (5 [3–6.2] vs. 8 [6–15] p < 0.001), days using triptans/month (2.5 [0–6] vs. 3 [0–8], p = 0.027) and intensity of pain (7 [5.8–10] vs. 9 [7–10], p = 0.012) were greater in the first visit for group P, while controls did not present a significant variation. The worsening of migraine-related indicators decreased in the following visits; however, even in the third visit, it had not returned to baseline. Correlations were significant between the delayed time to treatment and the increase in days/month with migraines at the first visit after lockdown (r = 0.507; p = 0.004). Conclusions There was a deterioration of migraine control after postponed treatments, with a direct correlation between the worsening of symptoms and the number of months that the treatment was delayed. Antecedentes Devido às medidas de resposta à pandemia de coronavirus disease 2019 (covid-19), a administração de toxina botulínica (TXB) foi adiada para muitos pacientes durante o primeiro confinamento em Portugal. Objetivos Avaliar o impacto do adiamento do tratamento com TXB no controle da enxaqueca. Métodos Estudo retrospectivo unicêntrico. Foram incluídos pacientes com enxaqueca crônica com pelo menos três ciclos prévios de TXB e que tenham sido considerados respondedores. Os pacientes foram divididos em dois grupos, sendo um com atraso do tratamento (grupo P) e outro sem atraso (controles). O protocolo Phase III Research Evaluating Migraine Prophylaxis Therapy (PREEMPT) foi utilizado. Dados clínicos relacionados com a enxaqueca foram obtidos na consulta inicial (T0) e nas três consultas subsequentes (T1–3). Resultados O presente estudo incluiu dois grupos, o grupo P (n = 30; 47,0 ± 14,5 anos; 27 mulheres, intervalo T0-1ª visita: 5,5 [4,1–5,8] meses) e o grupo controle (n = 6; 57,7 ± 13,2 anos; 6 mulheres; intervalo T0–1ª visita 3,0 [3,0–3,2] meses). Os grupos não apresentavam nenhuma diferença no início do estudo. Quando comparado à T0, o número de dias/mês com enxaqueca (5 [3–6,2] vs. 8 [6–15], p < 0,001), dias usando triptanos/mês (2,5 [0–6] vs. 3 [0–8], p = 0,027) e intensidade da dor (7 [5,8–10] vs. 9 [7–10], p = 0,012) foram maiores na primeira visita no grupo P, não apresentando os controles variação significativa. A piora dos indicadores relacionados com a enxaqueca diminuiu nas visitas seguintes; porém, mesmo na terceira visita, ainda não haviam retornado ao basal. As correlações foram significativas entre o atraso do tratamento e o aumento de dias/mês com enxaqueca na primeira consulta após o confinamento (r = 0,507; p = 0,004). Conclusão Houve piora clínica da enxaqueca após o adiamento do tratamento em correlação direta com a duração do atraso. HN, GV: collected and analyzed the data, and wrote the manuscript; SD: collected and analyzed the data, and reviewed the manuscript; CC, CA: designed the study, collected the data, and reviewed the manuscript. Received: 03 August 2022 Accepted: 10 October 2022 Article published online: 14 April 2023 © 2023. Academia Brasileira de Neurologia. This is an open access article published by Thieme under the terms of the Creative Commons Attribution 4.0 International License, permitting copying and reproduction so long as the original work is given appropriate credit (https://creativecommons.org/licenses/by/4.0/) Thieme Revinter Publicações Ltda. Rua do Matoso 170, Rio de Janeiro, RJ, CEP 20270-135, Brazil