Why do I get shortened duration of Botox over time?

The duration of your botox effect may be related to dose, interval between injections, the mass of muscle targeted, and technique of injection.  Potentiation from antibodies and an immune system response after multiple doses may also affect the duration of effect.  Some patients with active expression will require higher doses, more frequently, and by experienced injectors.  If the response continues to be disappointing, discuss with a qualified surgeon to consider alternative neurotoxins, radiofrequency modalities, or even surgical correction for the unwanted expression lines.

This is difficult to answer without an in-person evaluation, but it may be that more Botox is needed to get the results you want. See an expert. Best, Dr. Emer

Well, 20 units is a low dose and there may be variations in how the Botox was injected. You might have to increase your does or try Dysport. See an expert! Good luck. Dr. Aldo

Since you mentioned you have active facial muscles, it is possible that you need a larger dose of Botox to obtain longer duration of effect.  20 units of Botox would be considered an average dose for frown lines and it would not be usual to use a larger dose for that area in some people.  It is also possible that the injection technique could affect your results.  

Hello and thank you for your question. You have described an interesting factoid about Botox. Tachyphylaxis is a term associated with medications that loose some of their action with repetitive doses. In my patients who have had similar results I rotate between Xeomin and Botox. By doing this it breaks the tachyphylaxis chain and you get good results. Xeomin is made in Germany and has similar effects as Botox. Give it a try. Best of luck to you.

In general Botox lasts 3-4 months and patients tend to be fairly consistent with how long the individual effects last.  It may be injector technique or that more product is needed to produce the results that you like.  Placement of the Botox and dose can alter the results.

Hello majaps -
Botox, Dysport, and Xeomin lock the release of a chemical called acetylcholine, which triggers the muscle contractions that create wrinkles. Botox, Dysport, and Xeomin essentially paralyze the muscles and stops them from contracting. Results from these treatments are visible within two to four days with results that can last anywhere from 3-5 months. The results is in part related to the dosage used. Up to a certain point, the higher the dose, the longer the results last. It could be possible that not enough is being used to treat your frown lines fully. Next step for you is to see a board certified plastic surgeon or dermatologist.

The longevity of results is in part related to the dose used. Up to a certain point, the higher the dose, the longer the results last. Typically, Botox/Dysport results last 3-4 months. Maybe the dose is not enough for your frown lines. It's hard to comment further without seeing a photo or evaluating you in person. 

Most likely the reason that your botox doesn't last as long as you expect it to, is because you keep jumping to different treating Physicians. You should stick with the same person that you like and his administration technique appears to be a good one. You're also most likely using other muscles than make your face frown and those need to be addressed with botox as well. Good luck from New York City

Over a long period of time some patients make blocking antibodies to the toxin and this requires larger or more frequent injections; however, you have not been having the injections long enough and most likely it is the lack of skill of the injectors so be sure you see an experienced board certified dermatologist