Can Botox cause muscle weakness beyond the treatment area?
It is very unlikely for Botox Cosmetic® to spread outside of the intended areas when it is dosed appropriately and placed expertly by a trained, experienced, licensed medical professional. Local, temporary weakness in nearby muscles can happen; however, true “distant spread” causing generalized weakness is rare and is most often linked to counterfeit or mishandled product and unlicensed injectors.
At our Fort Worth medical spa, our team of Physician Assistant injectors use only name-brand, FDA-approved neuromodulators and precise techniques to help you safely achieve smooth, natural-looking results.
What “muscle weakness beyond the treatment area” really means
When people mention “muscle weakness beyond the treatment area,” they usually mean one of two scenarios: minor, nearby (adjacent) diffusion or the extremely rare distant spread.
Adjacent diffusion
Small amounts of Botox (and similar neurotoxins such as Dysport® and Daxxify®) can affect muscles next to the targeted muscles, which may lead to effects like temporary eyelid or brow droop (ptosis). But the rate of experiencing adjacent diffusion is very low. For example, studies show that eyelid and brow ptosis occur in only about 2% of patients (and resolved) after Botox treatment to forehead lines and glabella lines (frown “11” lines between the eyebrows).
Distant spread
The FDA includes a boxed warning because botulinum toxin could possibly have effects away from the injection site (trouble swallowing, speaking, or breathing). These events are uncommon at the very, very low cosmetic doses.
Related: Botox vs. Dysport vs. Daxxify: What’s the difference?
How Botox works, and where it goes
Botox (onabotulinumtoxinA) temporarily relaxes nerve signals to the injected muscle. The medication acts locally (within a small space) and, with typical cosmetic dosing, affects only the targeted muscle group. Published studies show that the spread is generally limited to nearby tissues within a few centimeters, which explains why side effects (when they occur) are usually local and temporary.
The FDA provides dosage recommendations for each approved treatment area in the upper face:
- 20 units for glabellar lines (“11s”)
- 24 units for crow’s feet
- 40 units for combined forehead + glabella
These dosing guidelines are designed to achieve pleasing results while reducing unintended effects. Keep in mind that you may not need the maximum amount of product per area. Our professional injectors carefully assess your unique facial muscles and discuss how smooth you want the treatment area before administering the appropriate dose.
Related: Are Off-Label Procedures Safe?
Who has a higher risk?
The overall risk is very low, but certain situations and medical histories can raise the chance of unwanted spread or temporary weakness.
Certain health conditions or medications
Neuromuscular disorders and medications that interfere with neuromuscular transmission can increase the chances of surrounding muscle weakness. Your safety is our top priority, and we review your full medical history and medication list during your consultation to ensure Botox treatments can safely achieve your goals.
Unlicensed or non-medical injectors or counterfeit products
In 2024 the CDC documented clusters of adverse effects tied to fake counterfeit or mishandled tox injected outside medical settings. The safety and success of your Botox treatments rely on the use of FDA-approved products and your injector’s knowledge and skill.
Related: How to Find a Safe Med Spa
“The staff at Kalos Med Spa @ Kirby Plastic Surgery are exceptional! I always know that I am in great hands with these ladies. A shout out to Mari today for her gentle touch with my Botox treatment. She always explains everything and is so sweet. I always feel comfortable and confident in her hands.”
—5-star Google Review
Aftercare that helps prevent unwanted spread
You can reduce the already low risk of Botox migration by following these simple and evidence-based steps after Botox injections in Fort Worth:
- Stay upright for 3-4 hours after treatment.
- Do not rub or massage treated areas for 24 hours.
- Skip strenuous activities and exercise for 24 hours.
These precautions help the product stay where your injector placed it as it quickly settles into the intended area.
Why choose Kalos Medical Spa in Fort Worth
Our physician-led medical spa is under the direction of Board-Certified Plastic Surgeon Dr. Emily Kirby. We exclusively use FDA-approved neuromodulators purchased directly from the manufacturers and follow label-based dosing and precise injection mapping to balance safety with smooth results.
Our expert injectors take care to personalize your treatment and review aftercare instructions so you feel confident at every step. Call or text (817) 292-4200 to book your appointment for natural Botox results today.
