Butt implants are made of solid silicone elastomer, a firm, rubbery medical-grade material that holds its shape permanently. Unlike breast implants, which contain liquid or gel inside a shell, the FDA-approved version of a gluteal implant is a single solid piece of silicone with no filling that can leak or spill.
Solid Silicone Elastomer: The Core Material
Silicone elastomer is a synthetic rubber-like polymer designed to be flexible enough to feel somewhat natural under muscle and fat, yet firm enough to maintain its contour under the constant pressure of sitting, walking, and exercising. Think of it as closer to a dense rubber eraser than to the squishy gel inside a breast implant. The material is carved or molded into specific shapes (round, oval, or teardrop) and comes in various sizes to match a patient’s body frame and goals.
In the United States, solid silicone elastomer is the only material the FDA has cleared for buttock augmentation. Manufacturers like Implantech Associates produce these implants from the same base silicone polymer family used across many surgical implant types, from chin implants to calf implants. The FDA does not approve the raw material itself. Instead, it evaluates the finished implant as a complete device, factoring in how the material was processed, sterilized, and shaped.
Cohesive Gel: The Alternative Used Abroad
Outside the U.S., particularly in South and Central America where gluteal augmentation is far more common, surgeons often prefer cohesive silicone gel implants instead. These have a soft, jelly-like interior held together by cross-linked silicone molecules, similar to what you’d find in a modern “gummy bear” breast implant. The consistency is noticeably different from solid elastomer. Cohesive gel implants feel softer and more pliable, which some surgeons argue produces a more natural look and feel in the buttock.
The tradeoff is that solid and gel implants interact with surrounding tissue differently. A solid block of silicone creates a different pressure profile against muscle and fat than a yielding gel does, which can influence everything from how the implant settles over time to how the body forms scar tissue around it. Neither type is universally considered superior; the choice depends on the surgeon’s training, the patient’s anatomy, and regional regulatory standards.
How Long the Material Lasts
Gluteal implants don’t last forever, even though they’re made from the same silicone family as breast implants. Research published in the Brazilian Journal of Plastic Surgery found the average time before reoperation was about 7 years, with the longest-lasting implants making it to around 14 years. Among implants that were reoperated on at the 7-year mark, only 1.4% were still fully intact.
The reason they wear out faster than breast implants comes down to physics. Your buttocks absorb far more mechanical stress than your chest. Every time you sit down, stand up, climb stairs, or exercise, those implants experience repeated cycles of compression and tension. Over years, this breaks down the silicone structure in ways that chest-placed implants simply don’t face. The more physically active you are, or the more time you spend sitting for work, the faster the material degrades. Surgeons familiar with these implants generally recommend periodic imaging (similar to what’s done for breast implants) to catch signs of wear before they become a problem.
Safety Testing and Biocompatibility
Before any silicone implant reaches the market, it goes through a battery of biological safety evaluations governed by an international standard called ISO 10993. These tests assess whether the material causes cell damage, triggers allergic reactions, irritates tissue, or poses any risk of toxicity over short and long exposure periods. The testing also looks at whether the material could cause genetic damage or interact poorly with blood.
The FDA requires that manufacturers submit complete experimental data for independent review. Testing must follow Good Laboratory Practice regulations, and the evaluation accounts for the implant’s specific placement in the body, how often it’s exposed to mechanical stress, and how long it’s intended to stay in place. If a material already has a well-documented safety record in the same physical form, manufacturers can sometimes rely on that existing evidence rather than running entirely new tests.
What Butt Implants Are Not Made Of
It’s worth understanding what legitimate implants are, partly because so many dangerous alternatives exist. Illegal “butt injections” offered outside of accredited medical settings often involve injectable liquid silicone, which is a completely different substance from the solid elastomer in approved implants. The FDA has specifically warned that these injections sometimes use industrial-grade silicone, the kind manufactured for machinery or construction, not for the human body.
Unlike a solid implant that stays in one place, liquid silicone can migrate through tissue, traveling to other parts of the body and causing serious complications including chronic pain, disfigurement, and life-threatening infections. Some patients seeking injections are told they’re receiving an FDA-approved dermal filler when they’re actually being injected with silicone. Injectable silicone is only FDA-approved for a single, narrow use: inside the eye during certain ophthalmic procedures. It has no approved role in body contouring of any kind.
Other non-medical substances that have been documented in illegal injection procedures include mineral oil, hydrogel, and even bathroom-grade caulking. None of these materials undergo biocompatibility testing, and none are designed to coexist safely with human tissue long-term. The complications from these substances can surface months or even years after injection, making them especially dangerous.