Botox is not permanent. This is both good and bad news. It is bad news because you have to spend more money for regular Botox injections to maintain wrinkle reduction. However, it's good news that Botox is temporary because if you get a botched job, your skin will return to normal in a few months.
The duration of time the results from a Botox treatment last depends on the dosage and application. If Botox is too diluted and you don't get the proper units injected, the results might not last very long. If you get Botox for the wrong kind of wrinkles (i.e. static wrinkles) or an improper dose for your anatomy, you might not see much improvement. If the right amount of Botox is injected by a skilled doctor in the correct muscles, Botox results can last 3-4 months.
Botox should certainly last longer than a few weeks. However, this can vary. First time Botox users may experience Botox wearing off in less than 3 months. Although, as facial muscles get conditioned to Botox, results should lengthen. Botox injections around the eyes can also last less than 3 months. On the other hand, men tend to need more Botox than women. Botox results should typically last around 3 months.
If you find that your Botox wears off too fast, speak your injector to find out why. It can be that the Botox was too diluted, not enough was injected, the Botox was old, your anatomy requires a different technique or you might be resistant to Botox. A respectable doctor will work with you to figure out how to make the Botox treatments worth your time and money. Keep in mind that for some people, Botox takes time to work. It can take approximately 1-2 days to be noticeable and 1-2 weeks to peak.