What are the long-term side effects of Botox?

I frequently  get asked how safe is Botox. I have used Botox for over 25 years and approximately 24 years on myself. Over the last 25 years I have never seen in on untoward side effect witj its use. When people have problems with Botox it is usually where the product was injected and by whom it was injected.  When I started injecting Botox I was one of two doctors in Miami. Now there are over 5000. Most are not qualified. If you are going to use Botox,make sure you’re being injected by a doctor vast experience. 

Most side effects of BOTOX tend to be minor and fade quickly (for example, redness or swelling at the injection site). Long-term, there should not be any lasting negative impact. Most people do continue BOTOX every 4 months or so, but there's no reason you have to. After a couple years of regular treatments, it's very common to find that your results last longer between visits.   

Thank you very much for your important question. Botox is the
most popular noninvasive treatment used in cosmetic surgery today. It safely
and effectively relaxes targeted muscles, smoothing skin for a more youthful
look. Botox has little chance for serious complications, and few negative
long-term side-effects. With regular Botox treatments, the target area will
continue to look smooth and youthful. However, once you have stopped Botox
injections, the muscles will return to their full function, meaning the
wrinkles and lines will return. How long you continue to use Botox will be up
to you, but the results are not permanent. I recommend finding a board certified
plastic surgeon in your area and scheduling a Botox consultation. At this time,
he/she can explain the pros and cons of treatment, as well as what to expect in
the long-term and answer any remaining questions.

Long term side effects of Botox are very rare.  It usually works for 3-6 months and then the effects go away.  Short term side effects like bruising and swelling are more likely.  Just make sure you are receiving your treatment from an experienced, qualified injector.

Botox is temporary and there is no evidence that stopping botox after using it regularly will make you age faster. The longer you use botox, the more likely you will have muscle atrophy (thinning of your muscles) and it may take several months for your muscles to recover to their normal strength and size once you stop. Hope this helps!Johnson C. Lee, MD Plastic Surgery@drjohnsonlee

Hello,
I have not experienced any long term effects of botox in my practice.  
There are many not so reputable places injecting botox and even injecting foreign things and claiming it is botox - that is where my concern would be.
Botox is not a permanent treatment and in the rare event that you even experience some of the rare short term complications, they are temporary.
Botox outcomes mainly depend on preparation of the actual botox, injector experience, and placement. If all those factors are appropriate botox outcomes should be rather predictable and patients should be happy!
Best wishes!

The long term side effects of Botox are all positive: increased collagen, decreased wrinkles and laxity, youthful appearing skin.  When you discontinue use the muscles rebuild and start moving at full strength again.  You do not have to use Botox forever, but you may want to because it will keep you looking more youthful for years.  All the best to you.  Enjoy your Botox.   Alexis Parker MD

Botox is for prevention not treatment.
The other important thing that is very important is that what botox does is that decreases muscle movement and as result the muscles lose muscle mass as result the skin becomes more lax.