Collagen Stimulators for Buttock Skin Laxity: Early Research in Men

A 2025 case report described three men who received a series of poly-L-lactic acid (PLLA) injections to improve loose skin and contour in the buttock area. The authors reported improvement in all three with only mild, short-lived side effects. With just three patients and no measured outcomes in the published summary, this is very early research, and it should not be read as evidence that the approach is established or suitable for most people.

Why this was studied

PLLA is a collagen-stimulating injectable. Rather than filling space directly, its microparticles trigger a gradual tissue response that builds collagen over several months. It has been studied mainly in the face, and more recently in body areas where skin has become thin or loose with age or weight change.

Most published body research has involved women. The authors noted that men's buttock anatomy, skin thickness and aesthetic goals differ, often with more interest in firmness and definition than in volume. They wanted to describe an injection approach adapted for male patients.

What the researchers did

This is a case report of three men aged 36, 41 and 50, treated at the authors' own institute in Brazil between 2023 and 2024. Each had four treatment sessions spaced four to six weeks apart. The product was reconstituted with sterile water and local anaesthetic and placed with a long blunt cannula in a curved pattern that the authors developed and named.

We were able to read only the published summary of this study, not the full paper, so details such as volumes, follow-up length and how results were assessed are not included here.

What they found

The study's summary reports improved buttock contour and skin laxity in all three men, which the authors attributed to new collagen, along with a firmer feel and better visible muscle definition. Side effects were limited to mild bruising, swelling and tenderness, and no nodules were observed. The summary does not report any numerical measurements of change.

How strong is this evidence?

A case report of three people sits near the bottom of the evidence ladder. It can describe a technique and show that it was tolerated in a few patients, but it cannot show how well it works, how often it works, how long results last or how safe it is across a wider group.

There was no control group, and with no measurements reported in the summary, improvement appears to rest on clinical impression and photographs. The technique was developed by the lead author and performed at the authors' own institute, which can introduce enthusiasm bias. Results in three men in one clinic may not apply to people with different body types, skin quality or goals.

Larger studies with standardised measurements and longer follow-up would be needed before drawing firm conclusions. Ideally these would compare the technique with no treatment or another approach, use independent assessors who do not know which patients were treated, and follow people for at least a year, since collagen-stimulating products can cause delayed lumps months after injection.

What it means for you

Using collagen stimulators in the buttocks is an emerging use that is still being researched. Whether a particular product is authorized by Health Canada for this area, and how it is used, varies, and many body uses are off-label. This article describes research only; it is not a description of a treatment offered by HealthPark. Please do not seek injections from unregulated sources, from non-medical settings or from products bought online, as body injections given in unsafe conditions can cause serious harm.

Even in medical settings, PLLA in the body carries risks. These include bruising, swelling and tenderness, small lumps or nodules under the skin, uneven results, infection, and, rarely, inflammatory reactions that can appear months later. Results build slowly over months, typically need multiple sessions, and are not permanent. Because changes are gradual, it can be hard to judge early on whether the treatment is working, and extra sessions add both cost and risk.

Some people should avoid or delay this kind of treatment, including those who are pregnant or breastfeeding, have active skin infection, a history of keloid scarring, certain autoimmune conditions, or bleeding risks. Never stop a prescribed blood thinner on your own before any procedure.

For many people concerned about buttock skin laxity, other options deserve consideration first: strength training of the gluteal muscles, stable weight, skin care, and checking whether loose skin after major weight loss might be better addressed surgically. Our articles on skin laxity after weight loss and body contouring for men explore these options.

Questions to ask at your consultation

• What is the evidence for this treatment in the body area I am concerned about?
• Is the product authorized in Canada for this use?
• What are the realistic results, and how would they be measured?
• What happens if lumps or uneven areas develop?
• Would exercise, weight changes or a surgical referral suit me better?

Frequently asked questions

Does PLLA add volume like filler?

Not in the same way. It works mainly by stimulating collagen over time, so changes are gradual. In this study, the focus was on firmness and laxity rather than adding size.

Are the results the same for men and women?

We do not know. This report only looked at three men, and most other body research has involved women. Differences in skin and anatomy may affect results.

How long do results last?

The study's summary does not say. In facial use, PLLA results are often reported to last longer than many hyaluronic acid fillers, but body results have been studied far less and vary from person to person.

If loose skin or body contour is bothering you, HealthPark Medical Aesthetics can talk through established options, what the research does and does not yet show, and when a referral to another specialist makes more sense.

Source

de Paula Barbosa A, Ferreira ACM, Duarte AC, da Silva RV. Novel therapeutic approaches with poly-L-lactic acid for treating gluteal skin laxity in male patients. Chinese Journal of Plastic and Reconstructive Surgery, 2025. Read the study