Which of the following is a known risk of BoNT-A cumulative dosing over time?

• A. Antibody development reducing responsiveness
• B. Weight gain
• C. Improved endurance
• D. Hair color change

Answer: (A)

Repeated BoNT-A dosing over time can lead to the development of neutralizing antibodies, which reduce how well the treatment works. When the immune system sees the toxin repeatedly, it may produce antibodies that bind to the toxin or its complexing proteins, blocking its ability to affect the neuromuscular junction. This can shorten the duration of benefit or cause partial or complete nonresponse to later injections. Factors that increase this risk include high cumulative doses, injections given too frequently, and long-term, repeated exposure.

The other options don’t reflect a recognized risk of cumulative BoNT-A use. Weight gain and hair color change are not associated with the toxin, and while improved endurance would be a desired outcome, it is not a risk.