Key takeaways
- Swelling, bruising, pain and numbness were each reported by most Kybella patients in the label's pooled trials.
- Some reactions lasted more than 30 days, most often numbness (42%).
- Nerve injury (4%) and trouble swallowing (2%) were rarer, and all trial cases resolved without treatment.
- Kybella is approved only for under-chin fat in adults; other areas are off-label.
- The label also warns of hair loss that may persist, necrosis, infection and nodules that may not resolve.
Common side effects
Kybella (deoxycholic acid injection 10 mg/mL) is an FDA-approved prescription drug, first approved in the US in 2015, for improving the appearance of moderate to severe fullness associated with submental fat — the fat under the chin — in adults.
The rates below are the label's own, pooled across its two trials: 513 people treated with Kybella and 506 with a placebo.
The label's most common adverse reactions, and the share of patients who reported each:
| Reaction | Share of Kybella patients |
|---|---|
| Swelling (edema) | 87% |
| Bruising (hematoma) | 72% |
| Pain | 70% |
| Numbness | 66% |
| Redness | 27% |
| Hardness (induration) | 23% |
| Tingling (paresthesia) | 14% |
| Nodules | 13% |
| Itching | 12% |
Compared with placebo, bruising was reported almost as often without the drug (70% on placebo, versus 72% with Kybella), while swelling (43%), pain (32%) and numbness (6%) were far less common on placebo.
Some of these lasted more than a month.
The label reports that reactions lasting more than 30 days, in more than 10% of Kybella patients, were injection-site numbness (42%), swelling (20%), pain (16%) and hardness (13%).
Reactions lasting more than 30 days
Share of Kybella patients
Source: Kybella label, pooled trials
The label reports duration in those brackets and gives no day-by-day swelling schedule.
Nerve injury and uneven smile
One trial reaction deserves its own explanation: marginal mandibular nerve injury, which showed up as an uneven smile or facial-muscle weakness.
It occurred in 4% of Kybella patients, versus under 1% on placebo.
Every case in the trials resolved without additional treatment, though the label's timeline is wide: a range of 1 to 298 days, with a median of 44 days.
Trouble swallowing (dysphagia) is the other reaction in this group — 2% of Kybella patients versus under 1% on placebo, occurring alongside swelling, pain and hardness in the treated area.
Those cases also resolved without treatment, with a median of 3 days and a range of 1 to 81 days.
The label's own instruction is specific: people with current or prior difficulty swallowing should avoid Kybella.
An uneven smile or new trouble swallowing after a session is something to raise promptly with the provider who treated you.
Rare risks
Beyond the reactions the trials counted, the label carries warnings for other risks.
These include injection-site hair loss (alopecia), which the label says may persist.
They also include ulceration and necrosis (tissue death), the latter a particular risk when injections are placed too superficially, and nodules or masses, some of which the label warns may not resolve.
Infection is on the list too: some injection-site infections have included cellulitis and abscess requiring intravenous antibiotic treatment and incision and drainage.
Where Kybella is used matters as much as how.
It is approved only for the under-chin area, is not approved for fat anywhere else, and the label says use outside the submental region is not recommended — so jawline, jowl, bra-fat or body treatments are off-label, meaning they are not on any current US label for this drug.
On the label
- Moderate to severe fullness from under-chin (submental) fat
- Adults
Off-label
- Jawline, jowl, bra-fat or body treatments
- The label says use outside the submental region is not recommended
The label also states that Kybella's safety and effectiveness have not been established in people under 18, that there are no adequate trials in pregnancy, and that it is not known whether the drug passes into breast milk.
Serious adverse reactions have been reported after unapproved administration of Kybella outside the under-chin region, per the label revised September 2026 — including blurred or reduced vision with use around the eyes, muscle or nerve injury such as facial paresis and paresthesia, and nodules or masses that may not resolve.
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Pain
Does Kybella hurt?
Pain was one of the most common trial reactions: 70% of Kybella patients reported injection-site pain, versus 32% on placebo.
It also lingered for some: injection-site pain lasting more than 30 days was reported by 16% of Kybella patients.
For comfort during treatment, the label suggests ice or cold packs and topical or injectable local anesthesia, such as lidocaine.
With pain reported by 70% of treated patients and swelling by 87% — and with injection-site pain still present past 30 days in 16% of patients, and swelling in 20% — it would not be accurate to describe Kybella as discomfort-free or downtime-free.
For the treatment itself — how sessions work, how it is dosed and what it costs — see our Kybella guide.
Frequently asked questions
How long do Kybella side effects last?
The label reports duration in brackets: reactions lasting more than 30 days occurred in more than 10% of patients for numbness (42%), swelling (20%), pain (16%) and hardness (13%), and it gives no day-by-day swelling schedule.
Among the rarer reactions, trial cases of nerve injury resolved without treatment over 1 to 298 days (median 44), and trouble swallowing over 1 to 81 days (median 3).
Does Kybella hurt?
Pain was one of the most common trial reactions: 70% of Kybella patients reported injection-site pain, versus 32% on placebo, and 16% had injection-site pain lasting more than 30 days.
For comfort during treatment, the label suggests ice or cold packs and topical or injectable local anesthesia, such as lidocaine.
Ask any provider you consult what they use for comfort during and after a session.
Is Kybella safe?
Kybella is an FDA-approved prescription drug for moderate to severe fullness from under-chin fat in adults.
Its trial record shows very common injection-site reactions — swelling 87%, bruising 72%, pain 70%, numbness 66% — plus rarer ones tracked separately: nerve injury in 4%, trouble swallowing in 2%, and label warnings of necrosis, infection, hair loss that may persist, and nodules that may not resolve.
The label states that safety has not been established under 18, that there are no adequate trials in pregnancy, and that it is not known whether Kybella passes into breast milk.
Whether it makes sense for you is a question for a licensed provider.
Can Kybella be used on the jawline or other areas?
No. Kybella is not approved for fat outside the under-chin (submental) region, and its label says such use is not recommended, so jawline, jowl or body use is off-label.
The label, revised September 2026, warns that serious reactions have been reported after unapproved use outside the region — including blurred or reduced vision with use around the eyes, facial muscle or nerve injury, and nodules or masses that may not resolve.
Sources
Every number on this page comes from one of these sources and was checked against it.
- KYBELLA- deoxycholic acid injection, solution · DailyMed, U.S. National Library of Medicine
Medical disclaimer. MedSpaStandard is for education only and is not medical advice. Talk to a licensed provider about your own health, and check any provider's license with your state board.