Wearing off occurs after 10 weeks with Botox. Dysport has a longer effective time, 12-14 weeks usually.

I have seen the wearing off effect starting at 10 weeks. I am not sure that you meant 3rd month?

Key Points
• Conclusion/Relevance: “In conclusion, BoNTA [Botulinum toxin type A] treatment was effective in pain control and reduction of analgesic use in chronic migraine patients. However, the efficiency duration was not as long as it is thought to be in clinical practice. From the 3rd month onwards, an increase in pain and painkiller use was seen. Therefore, future studies with additional doses or additional methods would shed light on the treatment of chronic migraine with BoNTA.”
• In the current study, researchers investigated the monthly change of BoNTA in 80 patients with chronic migraine. The patients were treatment naïve to BoNTA. Almost all the patients in the study responded with a significant reduction in analgesic intake and headache days during the first and second months following the initiation of BoNTA treatment. The researchers noted, however, a decrease in benefit at the third month. Moreover, the reduction of headache days reduced from month-to-month.
• “The higher monthly analgesic intake was a negative factor for the continuation of the decrease in the number of headache days,” wrote the authors.
• A strength of this study is that it is one of the first to assess the duration of BoNTA efficiency over the course of three months. Limitations of the current study include the lack of a placebo group. Another limitation is that the researchers did not evaluate the visual analog scale score, as well as migraine-related disability. Furthermore, the duration of follow-up was short.