Botox injections into the neck's sternocleidomastoid (SCM) muscles

The Effect of Injection of prabotulinumtoxinA-xvfs (Jeuveau) Into the Bilateral Sternocleidomastoid Muscles on Neck Circumference and Aesthetics

PHASE4 · Boston Medical Center · NCT06903975

This will try Botox (prabotulinumtoxinA-xvfs) injected into the sternocleidomastoid muscles to see if it temporarily slims the neck and creates a more feminine, youthful neck contour for adults seeking that change.

Quick facts

PhasePHASE4
Study typeInterventional
Enrollment30 (estimated)
Ages18 Years to 65 Years
SexAll
SponsorBoston Medical Center (other)
Locations1 site (Newton, Massachusetts)
Trial IDNCT06903975 on ClinicalTrials.gov

What this trial studies

Participants receive injections of prabotulinumtoxinA-xvfs into the sternocleidomastoid (SCM) muscles and are followed to measure neck circumference and aesthetic outcomes. Neck circumference is measured at four weeks post-injection and participants complete neck perception and self-confidence surveys to report subjective changes. Safety is tracked by collecting adverse events throughout the study period. The protocol excludes people with recent SCM neuromodulator injections, BMI over 30, anticoagulant use, pregnancy or breastfeeding, allergy to botulinum toxin, or anticipated major weight change.

Who should consider this trial

Good fit: Adults seeking a more feminine neck appearance who are not pregnant or breastfeeding, have BMI ≤30, are not on anticoagulants, and have not had SCM neuromodulator injections within the past year.

Not a fit: People with BMI over 30, current anticoagulant use, prior allergy to botulinum toxin, pregnancy or breastfeeding, or those expecting significant weight change are unlikely to receive benefit from this procedure.

Why it matters

Potential benefit: If successful, the injections could temporarily reduce neck circumference and improve neck contour and self-confidence.

How similar studies have performed: Injection of botulinum toxin into the SCM has established use for neck spasms, but using SCM injections specifically for cosmetic neck slimming is novel with limited prior evidence.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Age eligible individual seeking a more feminine neck appearance

Exclusion Criteria:

* Prior neuromodulator injections in the sternocleidomastoid muscles (SCM) within the past year
* Current anticoagulant use
* Body mass index (BMI) \>30
* Anticipation of significant weight gain or loss during the study period (e.g. patients taking or planning to take within the study period a semaglutide medication.)
* Prior allergy to botulinum toxin A
* Currently pregnant or breastfeeding

Where this trial is running

Newton, Massachusetts

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.

View on ClinicalTrials.gov →

Conditions: Neck Muscle Issue, Neck circumference, Neck aesthetics, Sternocleidomastoid muscles, Botulinum injection, PrabotulinumtoxinA-xvfs injection

Last reviewed 2026-05-15 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.