Collagen injections (such as Zyderm) and gelatin implants (such as Fibrel) can treat acne scars. They are injected through a needle directly into acne scars. They work by raising the level of the skin under the scar, which smoothes out the skin.

Collagen is a protein found in certain body tissues. Cattle are the source of most collagen used for treating acne scars.

Some people are allergic to the collagen. Redness, swelling, and itching are side effects of collagen injections and gelatin implants. In addition, gelatin implants may also cause hard bumps under the skin at the injection site.