The effects of Botox usually last three to four months, though longevity varies by area treated, dosage, metabolism

https://www.scribd.com/document/1027338542/Is-Botox-Safe-What-Certified-Clinics-Want-You-to-Know-145830

The effects of Botox usually last three to four months, though longevity varies by area treated, dosage, metabolism, and lifestyle factors; maintenance sessions help sustain consistent results.