Fat-Melting Injection Lumps: When to Call?

Bruising and swelling after a fat-dissolving injection usually settle in about 10 days, while a firm lump can take 3 to 4 weeks. In 515 people who had deoxycholic acid injected under the chin, bruising lasted a median of 9 days, swelling 10 days, and firmness 28 days. A lump that gets hotter and more painful each day, or a new one that pops up weeks later, is a different story, and it's worth calling about right away.

Why Is It More Swollen the Day After the Injection?

Why Is It More Swollen the Day After the Injection?

Feeling more swollen and sore the next day is a common reaction. Deoxycholic acid breaks down the walls of fat cells, and the body responds with inflammation that gradually clears the fat away. Swelling, warmth, and tenderness come with that inflammatory response.

Deoxycholic acid is a compound your body already makes to digest fat. As an injection, it's FDA-approved under the brand name Kybella, and just for fat under the chin.

In the two U.S. trials behind that approval, 87% of people had swelling, 72% had bruising, and 70% had pain. Keep in mind that people who got a placebo injection also had bruising (70%), swelling (43%), and pain (32%). In other words, the needle passing through fat many times causes some of this on its own. If you take blood thinners, bruising can spread wider.

Why Is It More Swollen the Day After the Injection?

How Long Does a Firm Lump Take to Go Down?

How Long Does a Firm Lump Take to Go Down?

Plan on 3 to 4 weeks. Lumps and firmness tend to outlast swelling. When the under-the-chin trials were pooled, 23% of people developed firmness that lasted a median of 28 days, and 13% developed small lumps that lasted a median of 23 days. Bruising and swelling, by comparison, were gone in about 10 days.

How Long Does a Firm Lump Take to Go Down?

Some reactions go past a month. Reactions that lasted more than 30 days included numbness (42%), swelling (20%), pain (16%), and firmness (13%). So a lump that's still there at week 2 isn't automatically a problem. What matters more is whether it's getting smaller and less tender.

There's much less data on the body. A small study of 14 people who had injections in the lower belly, with no comparison group, found swelling lasted an average of 9.6 days, bruising 7 days, and redness 2 days. Those patients received an average of 26.6 mL per session, more than the 10 mL maximum approved for under the chin. Higher doses were linked to longer redness but not to longer swelling. Under the chin, swelling, bruising, and pain became less common and milder with each session. Everyone heals a little differently.

Which Lumps Can Wait, and Which Need a Call?

Which Lumps Can Wait, and Which Need a Call?

A lump on its own isn't a warning sign. It's easier to tell the difference when you look at when it appeared, how it feels, and how it changes over time.

If anything in the right-hand column fits, don't wait it out. Contact the clinic that treated you right away if you notice:

• Redness that keeps spreading, with warmth and pain that get worse each day
• Pus or fluid draining from a lump
• Several new red, painful lumps 2 to 4 weeks after the injection
• Skin over the area breaking open or turning dark
• A lump larger than 3 cm, or one that hasn't shrunk after a few months

Injection-site infections that turned into cellulitis or an abscess, needing IV antibiotics and drainage, have been reported. In a Chinese series of 28 people with nontuberculous mycobacterial infections after cosmetic injections, 10 had received fat-dissolving injections, and symptoms took an average of 3 weeks to appear. These bacteria are relatives of the TB germ, though they don't cause TB, and they can enter through contaminated injections.

Accidental injection into a blood vessel has also been reported. For signs of a blocked blood vessel, the list the FDA gives for dermal fillers is a useful guide, even though it was written for fillers. Seek medical care right away for skin near the injection site that turns white, gray, or blue, or for unusual pain. Go to the nearest emergency room for vision changes or vision loss, or for signs of a stroke: sudden trouble speaking, numbness or weakness in the face, arms, or legs, trouble walking, face drooping, severe headache, dizziness, or confusion.

Do Face-Contouring or Body Injections Follow the Same Timeline?

Do Face-Contouring or Body Injections Follow the Same Timeline?

Not necessarily. Most of the numbers above come from deoxycholic acid by itself, injected under the chin, and in the U.S. it's approved for that area alone. The U.S. label also notes reports of blurred or reduced vision after use around the eyes, and lumps or masses that didn't go away, when the drug was used outside the chin area.

If your injection contained other ingredients, how long the swelling and lumps last may differ from these numbers. Knowing the date, the area, and the name of the product makes it easier to tell whether what you're seeing is within the expected range.

What Should You Send When You Contact the Clinic?

What Should You Send When You Contact the Clinic?

Start by counting the days since your injection. Swelling and bruising within about 10 days, and firmness within about a month, fall inside the expected range. If you're past that point, or the reaction is getting bigger instead of smaller, it's time to have it checked.

STON Clinic is in Seoul. If you'd like it to take a look, send the date of the injection, the area, the product name, and photos taken from the same distance each day. Mention the day the lump appeared, whether there's warmth or pus, and whether you take blood thinners. A front photo and a side photo in the same light, with a fingertip next to the lump, make size changes easier to compare. If your next session is coming up, also share when the last lump went away.