Botulinum Toxin Injections Do Not Cause Keloid Scarring
Botulinum toxin injections like Botox do not cause keloid scarring. The injection technique involves a needle puncture, but this is fundamentally different from the types of skin trauma that lead to keloid formation.
Understanding the Risk Context
The evidence clearly distinguishes between procedures that carry keloid risk and those that don't:
High-risk procedures: Tattooing, piercing, scarification, and other body modifications that create significant dermal injury are associated with keloid formation 1. Guidelines specifically warn that "the outcome is uncertain whenever there is trauma to the skin resulting in scar" for these procedures 1.
Botulinum toxin injections: These involve minimal dermal trauma—just a small needle puncture that heals without scarring in the vast majority of cases. The contraindications for botulinum toxin injection include neuromuscular disorders, allergies to constituents, and body dysmorphic disorder, but keloidal scarring is explicitly listed as a contraindication only for procedures involving significant skin trauma, not for botulinum toxin injections 2.
Clinical Evidence
The medical literature actually demonstrates that botulinum toxin is being studied and used as a treatment for keloids, not as a cause:
- Multiple studies have investigated intralesional botulinum toxin injection into existing keloids as a therapeutic intervention 3, 4, 5, 6, 7, 8
- A 2019 meta-analysis showed botulinum toxin was effective in treating hypertrophic scars and keloids 6
- Long-term safety studies of onabotulinumtoxinA across multiple indications show no reports of keloid formation as an adverse event 9, 10
One Exceptional Case
There is one isolated case report of a patient with a cavernous malformation who experienced hemorrhage after onabotulinumtoxinA injection for migraine, but this involved doses exceeding standard migraine protocols and was related to hemorrhage risk, not keloid formation 11. A subsequent study of 329 patients with cerebral or spinal cavernous malformations found that onabotulinumtoxinA (at doses <200 units) did not increase hemorrhage risk 11.
Clinical Bottom Line
- The needle puncture from botulinum toxin injection heals without clinically significant scarring
- Patients with a personal or family history of keloids can safely receive botulinum toxin injections
- The distinction is critical: keloids form from procedures that create substantial dermal injury and healing by secondary intention, not from simple needle punctures that heal by primary intention
- Minor bruising can occur with injection but is temporary and unrelated to keloid formation 2
There is no evidence-based reason to avoid botulinum toxin injections in patients with keloid-prone skin.