Deoxycholic Acid Dosing for Submental Fat Reduction
The FDA-approved dosing regimen for deoxycholic acid (Kybella) is 2 mg/cm² injected into the submental fat, with each treatment session consisting of up to 50 injections of 0.2 mL each (maximum 10 mL total per session), spaced 1 cm apart, with up to 6 treatment sessions administered at intervals of no less than 1 month apart. 1
Specific Dosing Parameters
Single Treatment Session:
- Dose concentration: 2 mg/cm² of treatment area 1
- Maximum injections per session: 50 injections 1
- Volume per injection: 0.2 mL 1
- Maximum total volume per session: 10 mL 1
- Injection spacing: 1 cm apart 1
Treatment Course:
- Maximum number of sessions: Up to 6 treatments 1
- Minimum interval between sessions: 1 month (approximately 28 days) 1, 2
- Average sessions required: Most patients need 3-4 sessions, with clinical trials showing 3.4 sessions on average 3
Critical Anatomical Considerations to Avoid Complications
Marginal Mandibular Nerve Protection:
- Do NOT inject above the inferior border of the mandible 1
- Do NOT inject within 1-1.5 cm below the inferior border of the mandible (from angle to mentum) to avoid nerve injury causing asymmetric smile 1
- Only inject within the designated target submental fat treatment area 1
Platysma Muscle Avoidance:
- Palpate the submental area before each treatment to identify pre-platysmal fat (subcutaneous fat between dermis and platysma) 1
- Avoid injecting into the platysma muscle itself 1
Patient Selection Criteria
Screen for contraindications:
- Rule out thyromegaly and cervical lymphadenopathy as alternative causes of submental fullness 1
- Exercise caution in patients with excessive skin laxity or prominent platysmal bands, as fat reduction may produce aesthetically undesirable outcomes 1
- Use caution in patients with prior surgical or aesthetic submental procedures due to altered anatomy and scar tissue 1
Expected Efficacy and Timeline
Treatment Response:
- 59-65% of patients achieve ≥1-point improvement on the Clinician-Reported Submental Fat Rating Scale 2
- 53-66% of patients report satisfaction with face/chin appearance 2
- Significant objective volume reduction confirmed by caliper measurements 4, 3
- Results assessed 12 weeks after the final treatment session 5, 2
Immediate Post-Treatment Changes:
- Expect an average 8.68% increase in submental volume during the immediate recovery period due to edema 3
- This swelling is self-resolving 3
Common Adverse Effects and Management
Expected Treatment-Area Reactions (typically mild-to-moderate and self-resolving):
- Edema (most common) 5, 6
- Local pain 6
- Bruising 6
- Numbness/paresthesia (occurs in all patients but self-resolves) 3
- These typically resolve within approximately one treatment interval (1 month) 5
Serious Complications to Monitor:
- Marginal mandibular nerve injury (presents as asymmetric smile from lip depressor paresis) 1
- Skin necrosis 6
- Alopecia 6
- Vascular events 6
Administration Requirements
Provider qualifications:
- Must be administered by a healthcare professional 1
- Provider must understand submental anatomy and neuromuscular structures 1
- Consider use of ice/cold packs, topical or injectable local anesthesia 1
Product inspection:
- Solution should be clear, colorless, and free of particulate matter 1
- Discard vial if discolored or contains particulates 1
- Discard any remaining solution after use 1
Key Clinical Pitfalls
- Never exceed 50 injections or 10 mL per treatment session to avoid excessive tissue damage 1
- Never inject closer than 1-1.5 cm below the mandibular border to prevent nerve injury 1
- Do not use in areas outside the submental region, as safety and efficacy have not been established 1
- Patient recovery scores improve with subsequent treatments, so counsel patients that early sessions may have more pronounced side effects 3