I had Microdermabrasion right after Botox treatment for my my forehead with 26 units. How bad can the side effects be?

In my practice, I recommend that adjunct cosmetic procedures (e.g. facials, microdermabrasions, massages, etc...) be performed PRIOR to Botox therapy because a RARE side effect is that the Botox could travel to places that it shouldn't after such treatments.  The risk is theoretical, and if your Botox was injected by an experienced "core" physician (facial
plastic surgeon, plastic surgeon, dermatologist, or occuloplastic
surgeon), it likely won't be a problem. 

In the interest of saving time and for overall promoting more gratifying rejuvenation results or of prolonging their duration, it has become common practice to combine in one treatment session the use of neuromodulators (such as Botox, Dysport, and Xeomin) with other rejuvenation techniques, including microdermabrasion or chemical peels, subcision and fractional medical microneedle therapy, and most notably the use of injectable fillers and volumizers, to name just a few. As a rule, when performing both procedures in the same session, it is best to save the Botox for last. The reason for this that, at least theoretically, whatever skin manipulation is required may disperse the injected Botox leading to unwanted side effects, say for example, as in this instance, possible lid droop from the Botox injected into the forehead. In practical terms, after over twenty-three years of experience using Botox for aesthetic reasons, I cannot recall a single instance of this actually happening. So, I think that there is little reason for concern here.As a sidebar, however, I question the value of microdermabrasion, which is in reality little more than "epidermabrasion," the kind of superficial abrasion and removal of the skin cells that might be gotten from a vigorous rubbing with a wash cloth, Buf-Puf or Loofah. I don't know what the problem is in the instance, but it might be worth a consultation with a board certified dermatologist to determine the exact nature of the problem and get a professional recommendation for the best and most cost-effective method to truly address it--be it chemical peels or home prescription medications, etc.

Usually, it is best to do the microdermabrasion or facial treatment prior to getting Botox. This is the suggested order because, although extremely rare, it is possible for the Botox to migrate to a different area. The Botox is injected into the muscle while the microdermabrasion addresses dead skin cell build-up on the outer layer of the epidermis. The Botox will not take effect, until at minimum 3-4 days but usually it takes 1-2 weeks. After 1 week, if you are not experiencing any adverse effects, you are probably in the clear. The chances of you having adverse effects are slim. In fact,  I can not think of any personal patient experiences that this has happened, but it is still possible. Just to be safe in the future, try to get the facial treatment first, then the Botox. It is also recommended to wait at least two weeks after having Botox to get any sort of facial treatments, microdermabrasions, or peels.   

The liklihood of developing any complication with this combination of treatments would be extremely rare. Microdermabrasion typically only removes the outer stratum corneum of your epidermis which we all slough every 72 hours. So it is not a deep enough treatment to propagate the results of a botox injection whichh in the forehead wiuld be injected into the muscle.  

It is not uncommon to have neurotoxin and other facial rejuvenation techniques on the same day as long as basic precautions are taken.  We commonly perform IPL, lasers and fillers on the same day as Botox Cosmetic but the treatments just need to be sequenced properly.  I don't anticipate any side effects but if you have any concerns, call your doctor.