Dermal fillers for acne scars: types and risks

A dermal filler is a gel that a doctor injects under a sunken acne scar to raise it level with the skin around it. The American Academy of Dermatology (AAD) says fillers add volume to depressed scars and "can also help your body produce more collagen and elastin to fill in the scars." Collagen and elastin are proteins that give skin its support and stretch. Fillers have one of the stronger evidence bases among acne scar treatments, but most results are temporary and the rare risks are serious. This guide covers the types of fillers, how long each lasts, what trials found, and what to ask. For every other option, see acne scar treatment.

Fillers treat dents in the skin. A flat red or brown mark left by a pimple is a color change that usually fades; see dark marks after pimples for those.

Which acne scars fillers suit

Fillers work mainly on rolling scars, the wide, shallow dips that make the skin look wavy. A 2017 review in the journal Scars, Burns and Healing found five filler studies, "mainly in patients with rolling type scars." The largest trial, published in 2014, enrolled people with at least four moderate to severe rolling scars. A 2023 review in the Annals of Dermatology describes a trial of calcium hydroxylapatite filler in which all treated people improved "with the exception of deep icepick scars." The guide types of acne scars explains each type.

Rolling scars are often held down by bands of tissue. The AAD says a dermatologist may first cut those bands with a procedure that lifts the scars, "and then inject a filler to give the treated scars more volume." See subcision for acne scars.

Types of fillers and how long they last

Fillers are grouped by how long the body takes to break them down. The AAD's filler chart gives these typical times:

Filler	How long it lasts (AAD)	What it is
Hyaluronic acid gel	4 to 12 months	A gel made of long chains of sugar units
Calcium hydroxylapatite	6 months to 1 year	Tiny beads of a mineral also found in bone, in a gel
Poly-L-lactic acid	1 to 3 years	A material that prompts the body to build collagen over weeks
Collagen	2 to 3 months, often longer when treating a scar	Protein filler
Your own fat	1 to 3 years, often longer when treating a scar	Fat taken from another part of your body
PMMA (polymethylmethacrylate)	Permanent	Tiny man-made beads in a gel that contains cow collagen

The AAD's acne scar page sums it up: "Most fillers give temporary results, ranging from 3 months to 2 years. A filler can also be permanent." Most fillers need a series of treatments, and "to retain your results, you'll also need touch-up visits. Even with a permanent filler, you may need touch-up treatment as your skin ages."

FDA approval for acne scars. The FDA says dermal fillers are approved for adults 22 and older for specific uses, including "correction of contour deficiencies, such as wrinkles and acne scars." It says "non-absorbable (permanent) fillers are approved for only nasolabial folds and cheek acne scars." The FDA describes PMMA beads as "tiny, round, smooth particles that are not absorbed by the body," suspended in a gel that contains cow collagen. The 2023 review says the FDA approved a PMMA filler for moderate to severe atrophic acne scars in December 2014. The FDA has "NOT approved liquid silicone or silicone gel for injection" anywhere in the body.

What the studies show

• A 2016 Cochrane review. This type of review pools trials to judge how strong the evidence is. It found "moderate-quality evidence that injectable filler might be effective for treating atrophic acne scars," the best grade it gave any scar treatment. It added that "no studies have assessed long-term effects, the longest follow-up being 48 weeks in one study only."
• The 2014 PMMA trial. Published in the Journal of the American Academy of Dermatology, it gave 147 people either PMMA filler or salt water injections, without telling them which. At six months, "success was achieved by 64% of those treated with PMMA-collagen compared with 33% of control subjects." The authors found no difference in results for people with darker skin. People were followed for only 6 months.
• Hyaluronic acid. The 2023 review found seven studies of hyaluronic acid fillers for acne scars, and all reported improvement with no or minimal side effects. In a small 2022 trial, 15 people had hyaluronic acid filler in one cheek and salt water in the other. The filler side improved more after 90 days, though the salt water side also improved a small amount.
• Poly-L-lactic acid. The 2023 review found five studies from 2007 to 2015, all with positive results, and mostly minor side effects such as pain, redness, swelling and bruising.

Most of these studies are small, and the 2023 review says the role of fillers in acne scars "is yet to be capitalized," meaning more research is needed.

Side effects and risks

The AAD says that after filler injections, some people have "minor, temporary side effects" such as redness, swelling, tenderness and occasional bruising, which "tend to clear within 7 to 14 days." It calls fillers "one of the safest cosmetic treatments available" when a trained doctor injects them.

The FDA lists more serious risks:

• Injection into a blood vessel. "The most concerning risk" is unintentional injection into a blood vessel. "While the chances of this happening are low, if it does happen, the resulting complications can be serious and may be permanent," including tissue death, "vision abnormalities including blindness, and stroke."
• Less common risks. Raised bumps under the skin called nodules or granulomas that may need treatment, infection, open sores and allergic reactions.
• Rare risks. Severe allergic reaction, movement of the filler away from where it was injected, leakage, permanent hard nodules, and death.
• Removal. Removing a filler may need injections or surgery, and "it may be difficult or impossible to remove the filler material, especially 'permanent' fillers."
• Keloids. "The safety of these products is unknown in patients who are prone to excessive scarring (keloids or hypertrophic scars)." See raised acne scars.

The FDA says to get immediate medical help for unusual pain, vision changes, skin near the injection that turns white, gray or blue, or any sign of a stroke during or soon after the procedure.

Where you get it matters. The AAD warns that having a filler injected in a non-medical setting is dangerous, and says never to get one at a spa, party, salon or someone's home. The FDA says not to inject yourself and not to buy fillers online. The AAD and FDA both warn against needle-free filler pens, which use pressure to force filler into the skin and have caused permanent damage.

Who should wait

The FDA says to tell your provider before treatment if you have inflamed or infected skin, a bleeding disorder, severe allergies, or allergies to collagen, eggs, animal products, lidocaine or bacteria, since some fillers contain these. "If you have an active inflammatory condition (cysts, pimples, rashes, or hives) or infection, dermal filler injection should be delayed." Safety is unknown during pregnancy, while breastfeeding and under age 22. The AAD also asks you to mention cold sore outbreaks, heart conditions, easily irritated skin, and medicines or supplements such as aspirin, ibuprofen, warfarin, vitamin E, garlic and ginger.

The appointment and recovery

The AAD says most filler treatments take 15 to 30 minutes. You may get ice or a numbing cream first, and you may feel stinging or burning during the injections. Most people return to normal activities right away. Afterward, the AAD advises waiting until the next day to exercise, staying out of the sun and tanning beds, and not touching the area for three days unless told to massage it. Poly-L-lactic acid is the exception: it requires gentle massage several times a day for 1 to 2 weeks.

Questions to ask

The AAD suggests asking:

• Are the results permanent or temporary?
• Is the filler FDA-approved for this use?
• What are the side effects, and do I have a higher risk?
• How many patients have you treated with this filler?
• May I see before-and-after photos?
• How much will the treatment cost?

The AAD's acne scar page says medical insurance does not cover acne scar treatment, and this guide found no independent medical source that lists filler prices.

When to see a dermatologist

See a dermatologist once your acne is under control and wide, shallow dents bother you. Skinli gives general education and is not a doctor. The free Skinli acne plan helps with the acne that comes first, and the guides on laser treatment and microneedling cover options that can be combined with fillers.