Botox injections use a neurotoxin to reduce signals from the nerves to the muscles, inhibiting contractions. Over time, the neurotoxin wears off, and the nerves begin sending signals to the muscles again. Although the length of effectiveness can vary from patient to patient, typically, Botox injections will last for three to four months.  Because of patient variability, some may experience longer durations of action, typically in the range of four to six months, while in others, a shorter duration of two to three months may be experienced. In addition, first-time users will often experience shorter durations of effectiveness, but repeat injections may last longer.