Why the route changes everything
A cream acts on the skin’s surface layers and very little reaches the bloodstream. An injection delivers the whole amount into the body. Dose, exposure, safety concerns and plausible benefits are all different, so evidence does not transfer from one route to the other.
What the topical research shows
GHK-Cu is a naturally occurring copper-binding peptide studied for skin remodeling in laboratory work and cosmetic products. In a small randomized trial after laser skin resurfacing, a GHK-Cu skincare regimen did not objectively improve redness, wrinkles or skin quality versus control, although patients using it rated their satisfaction higher.
What is known about injection
Very little in people. FDA’s safety review of injectable GHK-Cu notes possible immune reactions from aggregation and peptide-related impurities and limited human data. Claims that injections reverse aging, regrow hair or tighten skin are not supported by controlled human evidence.
Side by side
| Topical | Injectable | |
|---|---|---|
| Where it acts | Mostly the skin surface | Whole body |
| Human evidence | Small cosmetic studies, mixed results | Limited, per FDA |
| Main safety question | Skin irritation | Immune reactions, impurities |
| FDA-approved? | Cosmetics are not approved as drugs | No |