Aqualyx vs Kybella
Aqualyx is the fat-dissolving injection used in the UK and Europe, and it is used on the body as well as the chin. It is a weaker solution than Kybella, so a session covers a wider area and a course usually runs longer. Kybella is the version approved in the United States, for under the chin only. It has a fixed dose, a set schedule and side-effect rates counted in trials. They both work the same way, so where you live decides this more than anything else.
What is in the syringe
It is usually mixed with a local anaesthetic before injecting, so the treatment itself stings less.
The dose is set: a measured amount per point, points about a centimetre apart, and a ceiling per session. The molecule is made in a lab rather than taken from bile.
How it works
Deoxycholic acid is a substance your body already makes to break down fat from food. Injected into a fat pad, it damages the cell membranes.
Where it is used
Body areas are part of ordinary practice with it.
The maker states that use outside that area is not recommended.
How many sessions
Spaced three to four weeks apart. The weaker solution is part of why the course runs longer.
At least a month apart. Most people who respond do so by the third session.
Afterwards
The area swells and feels firm and sore for several days. Larger body areas swell for longer.
In the trials nearly everyone swelled, most bruised, and numbness was common. About 4% had a temporarily uneven smile from nerve irritation near the jaw, and every case settled by itself.
How the result looks
A gradual change over several weeks, judged best in photographs.
About 68% of people improved by one grade of chin fullness, against about 21% given a placebo injection. Fewer than one in five improved by two grades.
Cost
The at-home or drugstore version
Who each suits
The active ingredient is the same
Both rely on deoxycholic acid: It acts like a detergent on the fat cell wall, and the body clears the debris over the following weeks.
The strength and the rules around it are what differ: Kybella has one approved concentration and a dosing table. Aqualyx is weaker and the volume used is more a matter of the injector's judgement.
That is why a course looks different on each: More sessions, a wider spread, and a slower change on one side. Fewer, stronger sessions on the other.
Where you are decides most of this
Kybella is the product on offer in the United States: Aqualyx is not sold there.
Aqualyx is the product most UK and European clinics use: Kybella is available in some countries under the name Belkyra, and not in others.
So this is rarely a real choice: For most people the question is whether to have a fat-dissolving injection at all, not which brand.
What to expect either way
Expect a moderate change, over months: These are not liposuction. They thin a small pocket of fat, gradually.
Expect to swell: Swelling is not a side effect you hope to avoid. It is a sign the injection did something, and it lasts days to a couple of weeks.
Expect more than one session: Nobody finishes in one, and a clinic promising that is describing something other than what these products do.
Fullness is not always fat
Some of it is loose skin, which neither injection tightens. Taking away the fat under slack skin can make it look looser.
Some of it is muscle or jaw shape, and no fat treatment touches either.
Sort this out at the consultation, before the first injection: The wrong target is the most common reason people end up unhappy.
Before you book
Ask what you are being injected with, by name and strength, before the day.
Ask how many sessions the plan expects and what the whole course costs.
Say in advance if you take a blood thinner or have a bleeding disorder, because bruising is common with both.
Say in advance if you have ever had trouble swallowing, before any injection under the chin.
Ask who is injecting you, and what their training is.
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