Will I Get Permanent Side Effects if I Try Botox Just Once?

Botox is a very safe drug. Millions have used the treatment. It is the most popular cosmetic treatment in the world. That being said, there are always risks, (albeit very small), of any treatment.  Usually people like the result and then will keep up with the treatments.  It is important to choose your injector wisely. Ask questions about training and experience. Have realistic expectations, and take the time to tell your injector what your goals are.

I can reassure you
that if you try Botox once, it does not mean that you will have permanent
changes, and you do not have to continue with Botox treatments in the future.
The results of Botox wear off within 3-4 months, so that if you were unhappy in
any way with your treatment, your appearance will return to your baseline by
that time. However, most people love the results from their Botox treatment,
and want to continue with their treatments!

There are no substantial long term complications from botox, especially if you only try it once. Once the botox stops working, you should return to your normal appearance. If you use it long term, there may be some long term benefits with regard to lack of wrinkling in certain muscles.